june 2011 society journal

SOCIETY JOURNALJUNE 2011

June Society Meeting - The Observatories of Maunakea: Explorations and DiscoveriesShawn LaatSch, ImILoa aStronomy center of hawaII, monday JUne 13th 8Pm

maunakea is one of the best astronomical observing sites in the world. Located in the middle of the Pacific on the island of

hawaii, it has become the site for a variety of international observatories due to its near-perfect conditions. the mountain

features a variety of facilities from near-infrared to optical to radio. In this presentation, we will explore these observatories

and a few of their unique technologies viewing a variety of stunning astronomical images from them as well as learning about

their latest discoveries. we’ll explore topics such as star formation, new exoplanets, gas flows in the milky way, and galaxies far

beyond. along the way we will also discover why a place like hawaii, often thought of as a tropical paradise houses one of the

coldest places on our planet. come discover maunakea, mecca of astronomy!

Shawn Laatsch is Planetarium manager at the Imiloa astronomy center of hawaii and regularly works with the staff at the

maunakea observatories. he is also treasurer and membership chair of the International Planetarium Society and is on the Board

of directors of the astronomical Society of the Pacific.

Shawn will be speaking to us via video conference.

2 SOciETy JOurnal, JunE 2011

Haratina Mogasanu speaking to a packed meeting. The slide on the screen behind her shows the Mars Habitat with her team photographed in front of it.

May Society Meeting Simulating Martian Astronauts The Mars Simulation Project with Haratina MogasanuBy Clive Bolt & Gavin Logan

haratina has a formidable list of credentials. She immigrated to new

Zealand from romania after graduating with a masters degree in horticultural engineering. She has intense interest in astronomy and a burning desire to be an astronaut. She has had a long association with carter observatory and is the Journal editor for the wellington astronomical Society. more recently she was a founding member of the Kiwispace foundation where she is education co-ordinator.

In January of this year she was part of a romanian team that did a two week tour of duty aboard the mars Society’s, mars Simulation Project, a simulated mars habitat facility in the deserts of Utah where small teams of people (usually six) live for two weeks in an environment that attempts to simulate the conditions on mars. the program seems to be predicated on the theory that we have the technology to reach mars now and all that is required is the political and financial will. this is probably a tall order in the current economic climate.

there was a well-prepared graphic presentation explaining the mars direct scenario for visiting mars. In this concept, a rocket would carry all the requirements required for a mission to return from mars. It would include 6 tonnes of hydrogen that would be made into 18 tonnes of methane to be used as rocket fuel for the return journey home. a second rocket would take the crew to mars once the first lander had reported in with good health. the presentation did not go deeply into the logistical problems that this scenario could represent with such

issues as food, water, energy budget and fuel for a journey of six months each way and involving six astronauts. this presentation was preceded by a music video that acted to seduce the audience into believing that the whole scenario was quite possible and therefore it was reasonable for teams of young people to study being astronauts in the mars Society’s simulated habitat in the Utah desert.

In the mars habitat facility in Utah, team members dressed in heavy overalls to go outside wearing an enclosed helmet attached to a pump and filter and fitted with a radio, which one assumes it to simulate walking in space suits. Before going

outside, team members were required to sit in an “airlock” to simulate the tiresome delay required to decompress. Space suits have pressures significantly lower than the ambient cabin pressure of a spacecraft and as the atmospheric pressure on mars is about1% of the earth’s this probably makes the experience more accurate.

the facility is only used in winter where in the Utah desert night time temperatures drop to as low as -20 °c and the arid landscape has a certain martian-looking quality about it. from the photographs haratina showed the meeting, the clear dark sky at the habitat site was quite spectacular. the site has an observatory and telescope for team members to use.

haratina has immense enthusiasm that made up for any lack of detail about the It was very interesting to see attempts at putting such concepts into practice, but I suspect many more years of technical development in the field of space travel will be needed before such an idea can become reality.

It was great entertainment and wonderful to see someone with such enthusiasm for what she was doing, but also making such a great contribution to astronomy in this country.

The Mars Simulation Base in Utah

3www.aSTrOnOMy.Org.nz

Successful Public ViewingBy Gavin Logan

about 800 people saw telescopic views

of the moon and Saturn in market

Square at the Viaduct as part of the Society’s

Global astronomy month activities. a clear

sky on both friday and Saturday night in

the middle of may gave the public excellent

views at the Society’s two telescope viewing

evenings. at times quite lengthy queues

formed at the three telescopes being used.

many people commented on how sharp the

views of Saturn were.

lHc Smashes ‘Beam intensity’ world recordcern’s powerful accelerator has pushed particle physics into a new, powerful era.

• “Beam intensity” or “luminosity” is a measure of how dense the accelerated particles are as they collide.

• An increased density of colliding particles produces more collisions per square centimeter per second.

• This new record will help physicists optimise the search for the Higgs boson and other exotic physics.

the world’s biggest atom smasher has set a new world record for beam intensity, a key measure of performance and power, the european organization for nuclear research (cern) said friday.

on a quest to unlock some of the universe’s deepest secrets, the Large hadron collider (Lhc) in Geneva collided beams with a luminosity exceeding the mark set last year by the US tevatron accelerator, cern said.

In particle physics, luminosity affects the number of collisions -- the higher the luminosity, the more particles are likely to collide.

“Beam intensity is key to the success of the Lhc, so this is a very important step,” said cern director General rolf heuer. “high intensity means more data, and more data means greater discovery potential,” he said in a statement.

the new record measured a level of luminosity of 467,000 billion billion billion -- 467 followed by 30 zeros -- per square centimeter per second, which corresponds to several million particle collisions per second.

enhanced power boosts the odds of identifying extremely rare sub-atomic particles, especially the elusive higgs boson, or ‘God particle’. earlier experiments have found most of the tiny and ephemeral matter predicted by the so-called Standard model of particle physics -- except the higgs boson. many scientists believe only the 27-kilometer (16.8-mile), 3.9-billion-euro (5.2-billion-US-dollar) Lhc may be powerful enough to detect it.

Crowds line up to get a view of the Moon and Saturn through the Society’s telescopes.

the current run of Lhc experiments is set to continue through 2012, by which time it should be possible to determine if the higgs boson truly exists, cern said. “there’s a lot of excitement at cern today, and a tangible feeling that we’re on the threshold of new discovery,” said Serge Bertolucci, cern’s director for research and Scientific computing.

So far, cern has cranked the cathedral-sized machine up to energy levels of 7.0 trillion electron volts (teV), or 3.5 teV per beam, more than three times the level attained by any other accelerator.

It is aiming to trigger collisions at 14 teV -- equivalent to 99.99 percent of the speed of light -- in the cryogenically-cooled machine after 2011.

at full throttle, the collisions should create powerful but microscopic bursts of energy that mimic conditions close to the Big Bang.

even if validated, the Standard model only accounts for about five percent of energy and matter in the Universe.

dark matter and dark energy are thought to make up the rest, but have yet to be detected.


library corner with Tony Reynolds

STRAnGe new woRLdS By RAy JAyAwARdHAnA

Strange new worlds provides an insider’s look at the cutting-edge science of today’s planet hunters, our prospects for discovering alien life, and the debates and controversies at the forefront of extrasolar-planet research.

ray Jayawardhana is professor and canada research chair in observational astrophysics at the University of toronto, as well as an award-winning science writer.

catalogue section: QB820

ViSionS of THe UniVeRSe By dR RAMAn PRinJA

“a remarkable collection of photographs,

including the latest images from naSa, the

european Space agency, and the european

Southern observatory

catalogue section: QB44

feATURed SeCTion – QB85, ASTRonoMiCAL inSTRUMenTS

this section is where you’ll find all the books concerning building, testing and using telescopes and binoculars as well as the history of the telescope.

there are over a dozen titles including; how to make a telescope, Star testing astronomical telescopes and a very interesting book entitled Unusual telescopes.

feATURed SeCTion – yoUTH ASTRonoMy

Located in the lower left-hand corner of the shelves is the ‘kids’ section.

this is probably our most visited section in the entire collection with dozens of titles such as facts and records Book of Space, Into Infinity and 1000 facts on Space.

this section is serious fun, not to be underestimated!

These shape-shifting galaxies have taken on the form of a giant mask. The icy blue eyes are actually the cores of two merging galaxies, called NGC 2207 and IC 2163, and the mask is their spiral arms. The false-colored image consists of infrared data from NASA’s Spitzer Space Telescope (red) and visible data from NASA’s Hubble Space Telescope (blue/green). NGC 2207 and IC 2163 met and began a sort of gravitational tango about 40 million years ago. The two galaxies are tugging at each other, stimulating new stars to form. Eventually, this cosmic ball will come to an end, when the galaxies meld into one. The dancing duo is located 140 million light-years away in the Canis Major constellation.The infrared data from Spitzer highlights the galaxies’ dusty regions, while the visible data from Hubble indicates starlight. In the Hubble-only image (not pictured here), the dusty regions appear as dark lanes.The Hubble data correspond to light with wavelengths of .44 and .55 microns (blue and green, respectively). The Spitzer data represent light of 8 microns.


JULY PROGRAMME

fri 1 7:30 pm young astronomers with margaret arthur

mon 4 8.00pm Practical astronomy Using telescopes

mon 11 8:00pm monthly meetingSpeaker to be announced

mon 18 9:00pm film nighta selection of topical docu-mentaries

mon 25 8:00pm Introduction to astronomy with Bernie Brenner.

JUNE PROGRAMME

fri 3 7:30pm young astronomers

mon 6 8:00pm Practical astronomywinter observing night

mon 13 8:00pm monthly meetingthe observatories of mau-nakea: explorations and discoveries

mon 20 8:00pm film night

Journey to the Planets

mon 27 8:00pm Intro to astronomyastrology, astronomy and medicine

calendar and Events

JUNE INTRODUCTION TO AsTRONOMY Monday 27th June at 8:0pmAstrology, Astronomy and Medicine

with Bernie Brenner

an Introductory astronomy course will include a talk on astrology, astronomy and medicine.

the presentation will include a review of the polymath astronomers who were also medical doctors and examine the link of astrology in antiquity and the advent of aviation and Space medicine in modern day.

PRACTICAL AsTRONOMY - WINTER ObsERvING NIGhTMonday 6th June at 7:00pm, Planetarium at 8:00pm

this month is our seasonal observing event.

If the sky is clear we will start telescope viewing from 7pm onwards for those with early bedtimes. at 8pm we will move into the planetarium and take a tour of the highlights of the winter Sky. Bill thomas will also revises some of the open clusters he covered last month.

afterwards we will return to telescope viewing. the ewB Zeiss telescope will be available for viewing as well as portable telescopes outside in the courtyard. Ivan Vazey (aaS curator) will be on hand to help people who have questions about telescopes or your own telescope. feel free to bring your own telescope along.

If the weather is not suitable we will spend more time in the planetarium.

the evening is aimed to include members who are getting started with exploring the night sky as well as the more experienced so along and join in.

FILM NIGhT JUNE Monday 20th June from 8:00pmwith Gavin Logan

Journey to the Planets looks at the outer two planets Uranus and neptune and the ways in which a manned mission to them might be achieved.

It is 45 minutes long and will be followed by the december 2010 Sky at night show about Supernovas and Light echoes from them, which is about 30 minute long.

JUNE MONThLY MEETING Monday 13th June at 8:00pmspeaker: video Conference - shawn Laatsch

the observatories of maunakea: explorations and discoveries

maunakea is one of the best astronomical observing sites in the world. Located in the middle of the Pacific on the island of hawaii, it has become the site for a variety of international observatories due to its near-perfect conditions.

In this presentation, we will explore these observatories and a few of their unique technologies viewing a variety of stunning astronomical images from them as well as learning about their latest discoveries.

Shawn Laatsch is Planetarium manager at the Imiloa astronomy center of hawaii and regularly works with the staff at the maunakea observatories.

WELCOME NEW MEMbERs

trudy Lane (ordinary)anthony yen-Kai chen (youth)helen mcIvor (ordinary)Sam mcGillicudy (family)matthew Lake (youth)Lucious mann (youth)Blair Skelton (ordinary)Jacqueline fong (ordinary)chris hancock (ordinary)mark higgins (ordinary)


and fades in a pattern distinct from random twinkling, and the duration of brightening indicates the mass of the magnifying object.

Gregory Laughlin, an astronomer at the University of california at Santa cruz, says the authors have done a good job of ruling out other possible explanations for the light-distorting objects. But he adds that it’s difficult to speculate about the number of unbound, lower-mass planets on the basis of the wandering Jupiters, because that assumes that they were formed by a similar mechanism to planets in our neighbourhood. “I think we might be seeing a different formation mechanism here, something more similar to that of a tiny star than a giant planet,” he says. “But that’s just a hypothesis.”

Life on THe RoAd

Planetary scientist david Stevenson at the california Institute of technology in Pasadena has considered how the temperatures on ejected planets might compare with those on star-bound bodies2. If Jupiter were kicked out of the Solar System, its surface temperature would drop by only about 15 kelvin, he says – although it would still be unsuitable for supporting life. however, “when you eject a planet that is quite massive, it could have carried along an orbiting body”, Stevenson adds. “and that might be a more attractive possibility for life.”

Unbound earth-mass planets might still be capable of carrying liquid water, Stevenson says, even in the frozen reaches of interstellar space – as long as they have a heat-trapping hydrogen atmosphere. “that can bring the surface temperature up to 300 kelvin [about 27 °c],” he says. “and then you can have oceans.”

Study author david Bennett, an astrophysicist at the University of notre dame in Indiana, agrees that life could exist on these wandering worlds. he says that the next steps in the search include confirming the absence of host stars and looking through new data for the footprints of smaller, Saturn- or neptune-mass planets.

In the future, drifting earth-mass planets could be detected using naSa’s planned wide-field Infrared Survey telescope

Scattered about the milky way are floating, Jupiter-mass objects, which are likely to be planets wandering around the Galaxy’s core instead of orbiting host stars. But these planets aren’t rare occurrences in the interstellar sea: the drifters might be nearly twice as numerous as the most common stars.

“this is an amazing result, and if it’s right, the implications for planet formation are profound,” says astronomer debra fischer at yale University in new haven, connecticut.

to find the wanderers, scientists turned their telescopes towards the Galactic Bulge surrounding the centre of the milky way. Using a technique called gravitational microlensing, they detected 10 Jupiter-mass planets wandering far from light-giving stars. then they estimated the total number of such rogue planets, based on detection efficiency, microlensing-event probability and the relative rate of lensing caused by stars or planets. they concluded that there could be as many as 400 billion of these wandering planets, far outnumbering main-sequence stars such as our Sun. their work is published today in nature1.

UnexPeCTed BoUnTy

Study author takahiro Sumi, an astrophysicist at osaka University in Japan, says the deduced number of homeless exoplanets surprised him. “the existence of free-floating planets has been predicted by planetary formation theory, but nobody knew how many there are,” he says.

and because current theories of planet formation hold that lower-mass planets are more readily flung from developing planetary systems than are higher-mass planets, there could be a huge number of lighter planets on the loose. “they might be littering the Galaxy,” says fischer.

Sumi and scientists from the microlensing observations in astrophysics (moa) and optical Gravitational Lensing experiment (oGLe) collaborations used gravitational microlensing to detect the planets. microlensing involves measuring changes in the brightness of distant, background stars as a passing planet’s gravity bends and magnifies the starlight. as a result, the star brightens

(wfIrSt), a space-based telescope capable of resolving the more rapid bright blips associated with lower-mass objects. “detecting earth-mass unbound planets?” says Scott Gaudi, an astrophysicist at the ohio State University in columbus. “that would be very interesting.”

referenceS

1: the microlensing observations in astrophysics (moa) collaboration & the optical Gravitational Lensing experiment (oGLe) collaboration. nature 473, 349-352 (2011).

2: Stevenson, d. J. nature 400, 32 (1999).

So many lonely planets with no star to guide them By nadia drake - nature.com

Free-floating planets may be more common in our Galaxy than stars.NASA/JPL-Caltech/R. Hurt

MOA (Microlensing Observations in Astrophysics) is a Japan/NZ collaboration that makes observations on dark matter, extra-solar planets and stellar atmospheres using the gravitational microlensing technique at the Mt John Observatory in New Zealand pictured above.


around the world in 60 MinutesBy Gavin Logan

may film night was again well

attended with over 50 society

members seeing a film that followed the

international space station around one

orbit or the earth.

this film took the audience around the

planet to show what changes happen in

the time it takes to circumnavigate the

earth just once. how much pollution is

created from burning coal, how much

money is spent on the military, how much

volcanic activity is happening and many

other important issues. at 200 miles

above the earth it comments on what is

happening in each major region of the

planet as it flies overhead.

British-born astronaut Piers Sellers tells

what it’s like to live and work in space and

also to gaze down and see how we are

altering and reshaping our world.

It showed the incredible forces of nature

that bring hundred-mile wide storms and

reshapes continents, and also how we

humans are draining seas and building

cities in the middle of the desert. the

audience were also shown the wettest

place on earth, as well as the most

volcanic.

after that the January 2011 Sky at night

show with Patrick moore went beyond

the earth to review volcanic activity in the

Solar System.

next month’s film night is on monday

20th June, 8pm at Stardome observatory

and features the film “Journey to the

Planets” which looks at the outer two

planets Uranus and neptune and the ways

in which a manned mission to them might

be achieved. It is 45 minutes long and will

be followed by the december 2010 Sky at

night show about Supernovas and Light

echoes from them, which is about 30

minutes long.

A well attended May Film Night watching the International Space Station in Orbit above the Earth.

The Society Journal Team fRoM CLiVe BoLT - JoURnAL ediToR

I am looking ahead to when I stand down as editor of the Society Journal next year. I need some more people to help gather stories and write reports of local and national interest. I also need one or two new people to assemble the journal. we have templates available in both adobe Indesign and microsoft Publisher.

If you think you have the skills, or would like to learn, then please contact either Grant or myself. the journal assembly does not require you to find material. the journal is a great way to immerse yourself in the society and the latest developments in astronomy.


from gassing out during the eruption, thereby largely preserving the original water content of the underground rock.

“these samples provide the best window we have on the amount of water in the interior of the moon,” study co-author James Van orman, of case western reserve University, said in a statement.

So melt inclusions are special. they’re also rare, and finding the tiny structures in the small store of moon rocks available to researchers was by no means a given. But co-author thomas weinreich, at the time a freshman at Brown University, spotted some while poring over the apollo 17 samples.

“a kid a year out of high school found these for us,” hauri told SPace.com “that was pretty amazing in and of itself.”

other researchers had found melt inclusions in lunar samples before, but until now nobody had been able to measure their water content. Using a specialized ion microprobe, the team scrutinized seven melt inclusions, the largest just 30 microns across — smaller than the diameter of a human hair.

they found water contents ranging from 615 to 1,410 parts per million. those levels are about 100 times higher than previous studies of lunar magma had suggested, and they’re comparable to the concentrations found in the earth’s upper mantle. the melt inclusions also harboured earth-like levels of chlorine, fluorine and sulfur.

“we were really, really surprised,” hauri said. the researchers reported their results today (may 26) in the journal Science.

ReTHinkinG ModeLS of Moon’S oRiGinS

the team’s findings don’t cast serious doubt on the theory that a gigantic collision created the moon, hauri said. But the results indicate that researchers’ models of this cataclysmic event need a lot of work.

the models could be failing in their estimation of the energy released during the impact, according to hauri. the collision may have been less dramatic than scientists think, leaving some blasted-off earth chunks incompletely cooked. these pieces may have been able to hold onto some of their water before coalescing to form the moon.

But tweaking the energy levels downward wouldn‘t necessarily explain everything.

“certainly some of this [ejected] material has to have melted, so in that scenario it‘s still kind of hard to imagine that both the earth and the moon have the same amount of water,“ hauri said.

Just when we were starting to get over the shock that parts of the moon’s surface are wetter than the Sahara desert, a new study reports that the lunar interior is sopping wet, too.

Last october, scientists announced that a crater near the lunar south pole is jam-packed with water ice, likely holding a billion gallons of the stuff. now, new research has found that the moon’s insides are likely as wet as the earth’s upper mantle, the region just below its miles-thick surface crust.

this discovery, made by studying pieces of lunar magma hurled to the surface by ancient volcanic eruptions, comes as a big surprise.

the prevailing theory of the moon’s formation holds that it coalesced from pieces of the early earth blasted into space by a collision with a mars-size object long ago. Scientists had thought the massive energy produced by such a titanic impact would have baked the water out of the bits that became the moon. But that appears not to be the case.

“you really would not expect, based on what we know about this model, to have any water present in the moon at all,” said the study’s lead author, erik hauri, of the carnegie Institution of washington. “the fact that these [samples] have terrestrial levels of water is really a stunner.”

STUdyinG APoLLo Moon RoCkS

hauri and his team looked at bits of rock brought back to earth in 1972 by astronauts on naSa’s apollo 17 mission. Specifically, the researchers analyzed pieces called melt inclusions, which are minuscule globules of lunar magma encased within solid crystals.

these crystals prevented the magma’s water

conversely — and somewhat counter-intuitively — perhaps the impact was even more violent and energetic than researchers had imagined. If that‘s the case, it‘s possible that the collision vaporized some of the ejected rock, producing a thin but dense atmosphere that kept some water from escaping into space.

But this idea is no silver bullet, either, hauri said. at the moment, it‘s just difficult to account for the earth-like levels of water — and chlorine, fluorine and sulfur — in the moon‘s interior.

the new study „requires us to think hard about understanding the giant impact process at a level that‘s anything more than superficial,“ hauri said.

wHeRe did THe Moon‘S SURfACe wATeR CoMe fRoM?

most scientists think that the moon‘s prodigious stores of surface ice, which are chiefly concentrated in permanently shadowed craters near the poles, were deposited by comets and asteroids in the relatively recent past.

But the new study suggests that some of the stuff may be water from the lunar interior that was ejected by volcanic eruptions.

most of the moon‘s volcanism took place between 3.2 billion and 3.8 billion years ago. So any surface water originally from the moon‘s innards would be very, very old. that may be possible, as long as the moon‘s orientation has remained stable for a long time, keeping the ice-bearing craters shadowed for billions of years.

researchers will likely need a sample-return mission to figure out where the surface water actually came from, hauri said.

„If we had a little of that water back on earth, we could do some measurements on it that would be able to tell pretty quickly what the origin of that stuff is,“ hauri said.

the rock samples the researchers studied are deposits formed by explosive volcanism. Similar deposits are known to exist on many solar system bodies, including mercury, Venus, mars and the Jupiter moon Io, hauri said.

So he thinks future exploration missions to other worlds should make it a priority to investigate these deposits — and perhaps try to bring some home to earth.

„we‘ve shown in our study that this is really the best way to get at the water content of a planetary interior, and be able to tell whether a planet is actually capable of creating an ocean or an atmosphere through volcanic processes,“ hauri said. „we would really advocate pretty strongly that any sample-return mission should focus on this type of material.“

Moon’s interior wet as Earth’s, rocks indicate By Mike wall, SPACe.com

Backscatter electron image of a lunar melt inclusion from Apollo 17 sample 74220, enclosed within an olivine crystal. The inclusion is 30 microns in diameter. CREDIT: John Armstrong, Carnegie Institution of Washington


time of GP-B’s much-delayed launch, other confirmations of these effects were dissipating much of its rationale.

A LonG-SoUGHT GoAL

the experiment’s basic design was born in 1920, when physicists J. a. Schouten and arthur S. eddington suggested the use of gyroscopes to test general relativity. In 1959 mIt physicist donald Pugh suggested using a satellite, whose motion would be compensated for atmospheric drag, to provide a perfect, zero-g inertial reference frame in which to hold the gyroscopes. orbiting earth in a special housing at a height of 400 miles, GP-B’s gyroscopes consisted of four spheres the size of ping-pong balls coated with niobium. they were cited in the Guinness world records as the most perfectly spherical objects ever made. the housing was set to maintain a perfect lock on a guidestar (Im Pegasi). If newtonian physics were all that applied, the gyroscopes would never change orientation and stay pointed at the star. If einstein were right, the two effects would cause the gyroscopes to drift by a tiny angle, measured in arcseconds, over the course of the mission.

But GP-B’s confirmation of the geodetic effect to a precision of 0.3 percent (6,601.8 plus or minus 18.3 milliarcseconds) is not exactly stunning. astronomers had already done this to 0.002% accuracy, 150 times better, by measuring the time delay in radio signals from the cassini spacecraft as they passed through the gravitational field of the Sun.

you may have read the news on wednesday: albert einstein, time magazine’s “man of

the twentieth century,” indeed did not goof up when he put forth the theory of general relativity. naSa’s $750 million satellite Gravity Probe B proved that time and space do curve near massive objects like earth, and also that space and time are dragged along a tiny trace by earth’s rotation.

But wait a minute! didn’t we already know this? to high precision?

the truth is, we did. the LaGeoS satellites, lunar ranging, the cassini mission’s radio experiment, and binary pulsars, to name just a few, have all verified general relativity — including these two particular predictions — sometimes to much higher accuracy than Gravity Probe B (Sky & telescope, July 2005 issue, page 33).

at least Gravity Probe B will go down in history for being the only experiment to prove einstein right in one particular way so close to his home planet.

GP-B was the child of five decades of lobbying, planning, and execution. It was conceived in 1959 and launched in 2004 to test two predictions of general relativity. the first, the “geodetic effect,” describes the dent that earth causes in the fabric of spacetime because of its mass. for a two-dimensional analogy, think of a bowling ball sitting on a trampoline.

the second is “frame-dragging,” which Joseph Lense and hans thirring proposed in 1918 using einstein’s theory. this is the amount by which earth twists spacetime as it spins on its axis. “Imagine the earth as if it were immersed in honey,” says francis everitt, GP-B’s principal investigator at Stanford University. “as the planet rotates, the honey around it would swirl, and it’s the same with space and time.”

frame dragging results from a general-relativistic effect called gravitomagnetism —so named because it’s analogous to the way magnetism was revealed to be merely the special-relativity transformation of an electrostatic field that moves. So, just as a moving electron creates a magnetic field, a moving mass generates a gravitomagnetic field. the field exerts a sideways force, similar to the force a magnetic field exerts on a charged particle, on any mass moving though it, causing the object’s path to deflect.

this was heady stuff in 1959. But by the

“I am pleased but not impressed by the geodetic-precession part of the result,” said michael Kramer, a member of an international team studying binary pulsars and a contributor to S&t on the subject (august 2010 issue). “however, for the frame dragging [part], I still think it is a significant advance as it really shows a direct measurement of the effect on a spinning top, which is really quite nice.”

But GP-B confirmed frame-dragging to only 20% accuracy (37.2 plus or minus 7.2 milliarcseconds). Kramer called this “a very nice stone in the big mosaic to understand gravity,” while explaining that experiments on binary pulsars are aiming to calculate frame-dragging more precisely than GP-B.

and here, lunar-ranging experiments are way ahead. the apollo astronauts left retro-reflector mirrors on the moon, and laser ranging from earth can now track their positions to millimetres. at that level of precision, the moon’s motion in orbit has confirmed gravitomagnetism, the source of frame-dragging, to 0.15%, or 130 times better than GP-B.

“I won’t say there is no value in testing physics in a novel way,” says tom murphy (University of california in San diego), a member of the lunar-ranging project, “but any discrepancy would have been incredibly jarring.”

other physicists have said that if GP-B produced any other result than it did, they would probably just assume that GP-B’s engineers

gravity Probe B: relatively important? By Sky & Telescope

How Gravity Probe B detected the almost invisible effects of geodetic precession


had pushed their technology too far.

CoSTS And BenefiTS

So, was it worth $750 million?

naSa considered terminating the GP-B programme several times during its protracted existence. as recently as 2008 a panel of 15 scientists ranked GP-B last in a review of which space-science missions should receive funding. But a very perseverant team led by everitt lobbied congress hard to see the mission through to completion, bypassing normal channels.

Speaking at a naSa press conference on

wednesday, rex Geveden, GP-B’s program manager at the time of its launch (now the president of teledyne Brown engineering), said “Gravity Probe B is about science, technology and a triumph of the human spirit in the end.” the press-conference panel also boasted of GP-B’s educational value. the lengthy mission served as a training ground for 100 doctoral students, 15 other graduate students, 350 undergraduates, and over four dozen high-school students.

those who have long been following the mission heard a note of defensiveness here. every space mission involves students; rarely

does naSa have to cast that far to help justify it.

even so, one can’t help but wonder what einstein might have said if he were here to see the results. we can only look back to 1919, when shortly after the solar eclipse that provided general relativity’s very first (though weak) confirmation, he was asked what he might have felt if his prediction had been wrong. “I would feel sorry for the dear Lord,” he said. “the theory is correct.”

http://pigeonmountainobs.co.nz

New Zealand agents for SkyShed POD

Optional work bays can be added later as required.Each POD comes with DeepSky Planetarium software for run-ning your telescope.

With a POD you can be out observing in minutes on any night of your choice, leaving your equipment permanently set up.

No need to re-align your scope between each session.

You’ll wonder how you managed before POD.

You can also be assured that your valuable gear stays dry and safe, year round through any weather.

For colours & models contact Ivan at [email protected]

PIGEON MOUNTAINavailable in 6 Standard Configurations

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POD-XL5 A door panel and 5 work bays, plus 4 quadrant clamshell design revolving dome.

“It has been said that the best accessory for a telescope is an observatory”

PODs

Society Telescopes for Hire

the Society has a wide range of telescopes for hire to members.

If you are looking to purchase or upgrade a telescope and are not sure what to buy, this is a very good way to evaluate some of the available equipment. See also the advertisement on the back page.

to inquire about hiring or for advice on what to buy and for information about equipment, contact Ivan Vazey, curator of instruments, on (09) 535-3987


Burbidge Dinner Organising committeethe Society’s annual dinner is planned to be held at the end of october 2011. as one of the Society’s major events, we are wanting to form an organising committee to help plan this .

If you are interested in becoming part of this group, please contact andrew Buckingham on 09 473 5877 or email [email protected].

ThE 2010 COUNCIL

President Grant christie 021 024 04992Vice President david Britten 09 846 3657treasurer & andrew Buckingham 09 473 5877membershipSecretary Kleo Zois 022 691 2055curator of Ivan Vazey 09 535 3987InstrumentsLibrarian tony reynolds 09 480 8607 Journal editors clive Bolt 09 534 2946 Shaun fletcher 09 480 5648webmaster nick moore 09 537 1500 council Bernie Brenner 09 534 4103 council Gavin Logan 09 820 6001

sOCIETY CONTACTs

auckland astronomical Society Inc, Po Box 24187, royal oak, auckland 1345, new Zealand

email [email protected] [email protected] www.astronomy.org.nz

membership enquiries:contact andrew Buckingham at [email protected] or by phone on 09 473 5877 or 027 246 2446

It has been 401 years since Galileo first had the idea of pointing his telescope to the

heavens.

his interest in telescopes (an invention attributed to a dutchman) began for their military application and their commercial value. the astronomical science only occurred to him later and he was not the first as an englishman, thomas harriot drew the contours of the moon in July 1609 but gets no credit as he did not publish his work.

Galileo first found evidence that proved the earth was not the centre of the solar system when he found the four larger moons of Jupiter, and that Venus has phases just like our moon. these were seemingly simple things but in 1609 they turned science and the catholic church upside down. he did this with a telescope that was of poorer quality and less magnification than a cheap pair of modern binoculars.

Galileo’s eyes were not ideal. his left eye was very short-sighted and his right eye had less than perfect distance vision which meant they could never see together. his eyes pointed in different directions which is shown in many

existing portraits. he was reported to have poor vision, thought to be due to looking at the Sun, but his writings show that he was aware of the dangers of this and observed sunspots by projecting the Sun’s image onto a screen. this is a technique still commonly used by astronomers today. his weaker, divergent left eye may have helped him draw Jupiter and Venus as it was focused close to him while his right eye observed the heavens through a telescope.

experts agree that Galileo had progressive glaucoma. there is a study being undertaken by Paolo Galluzzi, director of the Institute and museum of the history of Science, in florence, Italy to undertake glaucoma dna studies from Galileo’s remains that were reburied in 1737 (his first grave was that of a pauper due to his being out of favour with the catholic church). he never married but did have three children so their descendents may have a family history of glaucoma?

Galileo is credited with applying scientific discovery of facts through evidence which is the same principle used in research into glaucoma and all the eye-drop treatments you may be using. no glaucoma treatment

galileo had glaucoma from “eyelights”, the newsletter of glaucoma new Zealand.

reaches an eye unless it has had rigorous

studies proving that it works with similar

confidence to the knowledge that the Sun is

the centre of our solar system.


The Hottest, Densest Super-Earth yetBy Sky and Telescope

on a very dark and clear night far from city lights, you can just make out 55 cancri as a 6.0-magnitude pinprick in northern cancer. Shining from 41 light-years away, it’s a main-sequence G8 star a little cooler and dimmer than the Sun. Last friday it became the brightest star in the sky known to have a planet transiting across its face.

the planet is 55 cancri e, the closest of the star’s five known worlds. all were discovered by the radial-velocity wobbles that they induce in the star. the wobbling due to planet e was teased out of complex radial-velocity patterns in 2004. Its strength tells that planet e has only 8.6 ± 0.6 earth masses — a super-earth.

astronomers had assumed that 55 cnc e revolves around the star every 2.8 days. But in late 2010 a paper by rebekah dawson, a graduate student at harvard, and her colleague dan fabrycky, now at the University of california in Santa cruz, analysed the data differently. they proposed that its orbital period is four times faster: that it circles the star in 17

hours 41 minutes. this would put the planet even closer to the star, increasing the likelihood that it might cross the star’s face as seen from earth.

now a team led by Joshua winn (mIt) confirms that 55 cnc e indeed transits its sun. the team has observed 17 transits using canada’s moSt (microvariability and oscillations of Stars) satellite, the world’s first astroseismology space telescope. moSt studies the internal pulsations of stars by tracking tiny variations in their brightness).

“I’m excited that by calculating the planet’s true orbital period, we were able to detect transits, which tell us so much more about it,” said dawson.

In particular, the amount of dimming during the transits tells that the object has a diameter 60% larger than earth’s. combined with its mass, this yields an average density of 11 ± 3 grams per cubic centimetre — higher than earth’s value of 5.5 g/cm³, and implying a large iron core overlain by rock. the surface gravity must be about 3 gs.

dawson and fabrycky were inspired to reexamine the wobble data by a paper that mIt astronomer Jack wisdom circulated informally in 2005, pointing

out the possible ambiguity of the orbits in the 55 cancri system. while radial-velocity tracking has been the mainstay of exoplanet hunters, it has its limitations. daylight, clouds, and scheduling cause periodic gaps in the observations (which must be done at a large observatory on the ground), creating spurious wobble periods, called aliases, that would not occur if the observations were continuous. dawson and fabrycky studied the patterns of these aliases and devised a method to set them apart from true wobble periods. this led to the discovery of the planet’s correct orbit.

family portraits of two planetary systems: a simulation of the silhouette of planet 55 cancri e transiting its parent star, compared to earth and Jupiter transiting our Sun.

J.rowe (naSa-ames & SetI Inst. / Jaymie matthews (UBc)Planet e not only holds the record for transiting a naked-eye star, but it also has the fastest orbital period of any exoplanet known. It’s even closer to its star than corot-7b (the “Planet from hell” featured in Sky & telescope in may 2009) and the similar Kepler-10b (april 2011 issue, page 12). Its star-facing side should be as hot as 4890° f (2970 K), making this also the hottest known world.

Barely glimmering to the naked eye north of the Beehive Star Cluster, 55 Cancri forms a nice pair with 53 Cancri for binocular ob-servers. How many other ordinary-looking stars hold such secrets?Akira Fujii

Top: All of MOST’s brightness observations of 55 Cancri over 14 days, with a few gaps. Bottom: All the transits of planet e overlaid on each other. The red line shows a best fit.Joshua Winn & others


Being so close to its star it must be tidally locked, so that one side always faces the star and the other always faces away.

all three of these roasted super-earths have similar high densities and seem to form a class of their own. But since it orbits a star as bright as 6th magnitude, 55 cancri e holds special promise for future study. “It is very exciting that we have a planet around a bright star,” said Sara Seager, an mIt expert on exoplanets who has contributed to Sky & telescope.. “we can study it in a way Kepler-10b and corot-7b cannot be observed.” their stars are magnitudes 11.0 and 11.7, respectively.

super-earth so close to its star should be stripped of most of its atmosphere due to both heat and furious stellar wind, according to an analysis by Joshua winn’s team. on the other hand, a paper by Brice-olivier demory (mIt) in may 3rd’s astrophysical Journal suggests that maybe this is wrong. the Spitzer Space telescope’s infrared cameras recorded a single transit in January 2011, and it found the planet’s radius to be 30% larger than that deduced from moSt’s observations. this disparity could be caused by thin gases in a very extended outer atmosphere blocking infrared but not visible wavelengths. Seager says that further observations with space telescopes like Spitzer and hubble will be necessary before coming to any conclusion about an atmosphere.

could amateurs possibly get in the game? the transits dim 55 cancri by only 0.0002 magnitude, or two parts in 10,000, much less than even the best amateur photometrists can normally detect. But Greg Laughlin (University of california, Santa cruz) thinks it could be done nonetheless. “the transit depth is small enough that you would definitely need to observe multiple transits and then stack the data,” he says, “but I think that some of the top amateurs could do it.”

take that as a challenge

Family portraits of two planetary systems: A simulation of the silhouette of planet 55 Cancri e transiting its parent star, compared to Earth and Jupiter transiting our Sun.J.Rowe (NASA-Ames & SETI Inst. / Jaymie Matthews (UBC)

an artist’s portrayal of the star 55 cancri and its innermost planet.

Univ. of texas / naSa / nSfa

naSa unveils new Spaceship for Deep Space

Exploration by Space.Com

naSa on tuesday announced a plan to develop a new deep space vehicle, one based on an earlier capsule concept, in order to send astronauts on expeditions to an asteroid, and then on to mars.

the spaceship, known as the multi-Purpose crew Vehicle (mPcV), will be based on designs originally planned for the orion spacecraft, naSa officials announced today (may 24). orion was part of naSa’s now-canceled constellation program, which aimed to return astronauts to the moon by the 2020s.

President Barack obama shut down the constellation program last year, tasking naSa instead with sending people to an asteroid by 2025, and then to aim for crewed mars missions by the 2030s. modifying the orion capsule design — rather than drawing up plans for an entirely new spaceship — should help make that feasible, agency officials said.

“we made this choice based on the progress that’s been made to date,” doug cooke, associate administrator for naSa’s exploration Systems mission directorate in washington, d.c., told reporters today. “It made the most sense to stick with it [the orion design].”

NASA’s Multi-Purpose Crew Vehicle Concept Credit: NASA


The Evening Sky in June 2011By Alan Gilmore, University of Canterbury‘s Mt John observatory, www.canterbury.ac.nz

Sirius, the brightest star, appears low in the western sky at dusk before setting in the southwest. It twinkles with all colours like a dia-mond. canopus is higher in the southwest sky, circling lower into the south later on. crux, the Southern cross, with Beta and alpha centauri are south of overhead. Scorpius, upside down, is midway up the eastern sky. Below it is Sagit-tarius; its brighter stars making ‘the teapot’.

midway down the north sky are Saturn and Spica, similar in brightness and colour. Saturn is the lower of the two and has a creamy colour. Below and right of them is orange arcturus,

often twinkling red and green. arcturus is 120 light years away and 37 times brighter than the sun. It is the fourth brightest star in the sky af-ter Sirius, canopus and alpha centauri.

crux, the Southern cross, is south of the ze-nith. Beside it and brighter are Beta and alpha centauri, often called ‘the Pointers’ because they point at crux. alpha centauri is the clos-est naked-eye star, 4.3 light years away. a tel-escope shows it is a binary star: two suns orbit-ing each other in 80 years. Beta centauri and many of the stars in crux are hot, extremely blue-giant stars hundreds of light years away.

canopus is also very luminous and distant: 13 000 times brighter than the sun and 300 light years away.

Scorpius is midway up the eastern sky, lying on its back. Its brightest star is orange antares, marking the scorpion’s heart. antares is a red giant star: 600 light years away and 19 000 times brighter than the sun. red giants are much bigger than the sun but much cooler, hence the red colour. they are dying stars, wringing the last of the thermonuclear energy from their cores. antares will end in a spectacu-lar supernova explosion in a few million years.


the milky way is brightest and broadest in the southeast toward Scorpius and Sagittarius. It remains bright but narrower through crux and carina then fades in the western sky. the milky way is our edgewise view of the galaxy, the pancake of billions of stars of which the sun is just one. the thick hub of the galaxy, 30 000 light years away, is in Sagittarius. a scan along the milky way with binoculars will find many clusters of stars and some glowing gas clouds. relatively nearby dark clouds of dust and gas are silhouetted as holes and slots in the milky way.

the clouds of magellan, Lmc and Smc are in the lower southern sky, easily seen by eye on a dark moonless night. they are two small gal-axies 160 000 and 200 000 light years away. they are only a fraction of the mass of our gal-

axy but still contain many billions of stars.

Saturn’s rings are “opening” now after be-ing edge-on in recent years. a small telescope will show the rings and Saturn’s biggest moon titan about four ring-diameters from Saturn. other smaller moons appear as faint stars close to Saturn. Saturn is around 1400 million km away. In June Saturn is close to the star Gam-ma Virginis, also known as Porrima. It is a bi-nary star -- two stars orbiting each other -- but the stars are now close together and difficult to separate in a telescope.

Jupiter (not shown) rises in the east around 4 a.m. It shines brightly with a steady golden light. Brilliant silver Venus rises in the northeast after 6 a.m. at the beginning of June, mars is above Venus, looking like an orange ‘star’

much fainter than Venus. mercury is below Venus and bright. By mid month mercury will have disappeared into the twilight and Venus will be very low in the dawn. around the 20th mars will be right of matariki, the Pleiades star cluster, which is just appearing in the dawn twilight. Jupiter is 830 million km away. mer-cury, Venus and mars are all on the far side of the sun; their distances 200 million, 250 million and 340 million km respectively at mid month.

on the morning of June 16 we see the start of a total lunar eclipse. the full moon begins to move into earth’s outer shadow at 5:23 am. It touches the dark inner shadow, the umbra, at 6:23. By 7:22 it is fully in the umbra. Being exactly opposite the sun, the totally eclipsed moon sets at sunrise.

Diary of Solar System Events June 2011By Brian Loader RASnZ

June 2 new moon at 9.03am nZSt (Jun 1, 21:03Ut). Partial eclipse of sun visible from the arctic.

June 2 moon furthest north, so lowest southern hemisphere transit for the month.

June 3 neptune stationary.

June 7/8 30% lit moon 8.6° left of regulus, α Leo, magnitude 1.4 on the 7th and 41% moon 8° above regulus on the 8th, evening sky.

June 9 moon at first quarter at 2.11am nZSt (02:11 Ut).

June 10 65% lit moon 8° left of Saturn, late evening sky.

June 11 75% lit moon 4° left of Spica, α Virginis, magnitude 1.1, late evening sky.

June 12 moon at perigee, its closest to the earth for the lunar month, 367189 km.

June 13 mercury at superior conjunction between Sun and earth.

June 14 Saturn stationary.

June 14 97% lit moon 6° left of antares, α Scorpii, magnitude 1.1, late evening sky.

June 15 moon furthest south, so highest southern hemisphere transit for the month.

June 16 full moon at 8.14am nZSt (Jun 15, 20:14Ut). total eclipse of moon, moon sets during totality as seen from nZ.

June 18 Venus 4.7° to lower left of aldebaran, α tauri, magnitude 1.0, low in dawn sky.

June 22 Southern midwinter solstice, sun furthest north at 5.17am, nZSt (Jun 21, 17:17Ut).

June 23 moon at last quarter 11.48pm nZSt (11:48 Ut).

June 24 47% lit moon 6.5° below Uranus, magnitude 5.8, dawn sky.

June 24 moon at apogee, its greatest distance from the earth for the Lunar month, 404274 km.

June 26 29% lit moon 7.5° left of Jupiter, morning sky.

June 28 Pluto at opposition.

June 29 7% lit crescent moon 2.6° below mars, magnitude 1.4, early dawn sky.

June 30 moon furthest north, so lowest southern hemisphere transit for the month.

June 30 2.5% lit crescent moon 5° to upper left of Venus, low to ne in dawn sky.

date (nZdt) dIary of SoLar SyStem eVentS In JUne 2011 for new ZeaLand


The Solar System in June 2011By Alan Gilmore, University of Canterbury‘s Mt John observatory, www.canterbury.ac.nz

JUne SoLSTiCe

the southern winter solstice and shortest day is on June 22. the sun is furthest north at 5.17 am nZSt and will be at its lowest midday altitude. In the northern hemi-sphere this is the summer solstice with the longest day.

THe MAJoR PLAneTS in JUne 2011

the 4 planets in the morning sky will be spreading out after their close grouping in may. mercury will disappear into the morn-ing twilight at the start of the month and Venus will get very low. while mars main-

tains its rather low altitude in the dawn sky, Jupiter will get steadily higher.

In the evening sky Saturn will continue to be readily visible.

a total eclipse of the moon occurs on the morning of June 16 (nZSt). the moon en-ters the penumbra just after 5.24 am, nZSt. It starts moving into the total shadow of the umbra almost an hour later. By then the moon will be getting low in nZ. the eclipse becomes total just after 7.22am but will then be close to setting in nZ, especially in the north. mid eclipse is at 8.13 am, by

which time the moon will be set in all of nZ north of timaru. It sets 10 minutes later in dunedin and 20 minutes later in Inver-cargill. the end of the total eclipse will not be visible in any part of nZ.

australia will have a better view but even there, in the east, the moon will set before the end of the total eclipse. only in the west of australia are all stages of the eclipse vis-ible.

a partial eclipse of the Sun on June 1 is only visible from arctic regions of the northern hemisphere.

crux by Paul Rodmell, Southland Astronomical Society

CRUx, PRonoUnCed CRUCkS, THe SoUTHeRn CRoSS

crux, the Southern cross, is the smallest constellation in the sky, but one of the most celebrated. the early Portuguese navigators saw

it as a symbol of their faith, and the mystery of the unknown lent it an additional charm in the minds of those from whom the southern

skies were hidden. there are other cross patterns formed by stars, but the distinguishing feature of the two bright pointers alpha and beta

centauri make crux unmistakable.

crux lies in a dense and brilliant part of the milky way, which makes the famous dark nebula known as the coalsack striking in silhouette

against the star background. this is the head of the emu to the native aborigines of australia. the rest of the emu is made from the dark

lanes in the milky way.

from new Zealand latitudes crux is circumpolar and always in the sky, rotating about the south celestial pole each day.


Low energy spectrum from the CoGeNT experiment

to 10 times the mass of a proton, says Katherine freese of the University of michigan in ann arbor. recent results from other experiments appear to be in conflict with the experiment but may not be as sensitive as coGent is to collisions with such low-mass particles (Sn: 5/7/11, p. 12).

the coGent finding intrigues freese, who, with other researchers, predicted in the 1980s that a seasonal variation could be a sign of dark matter. that idea envisions vast halos of wImPs engulfing galaxies, including the milky way. earth would plow through the milky way’s wImP halo faster in northern summer than winter because its revolution around the sun would then correspond with the rotation of the galaxy into the wImP halo. In northern

an experiment in minnesota is the first to bolster a long-contested claim that

detectors a continent away have found evidence of particles called wImPs.

wImPs are theorized particles considered to be leading candidates for dark matter, invisible material believed to make up more than 80 percent of the matter in the universe. In the minnesota experiment, called coGent, a hockey puck–sized chunk of germanium deep in a former iron mine attempts to record rare collisions with wImPS.

In 15 months’ worth of data, coGent researchers detected a seasonal variation in the collision rate — higher in northern summer and lower in winter — similar to that seen for 13 years by a larger experiment, using different detectors, in Italy. researchers with that experiment, dama/LIBra, have attributed the results to the earth’s motion through a cloud of wImPs (for weakly interacting massive particles) (Sn: 5/10/08, p. 12). But many physicists have doubted that interpretation because, until now, no other experiment had found similar results.

coGent team leader Juan collar of the University of chicago presented the new findings may 2 in anaheim, calif., at a meeting of the american Physical Society. collar said he would not discuss the results with reporters until after papers describing the work are posted online.

the new coGent results have features that you would expect from a dark matter detection, “something pretty similar to what dama has seen,” says theorist dan hooper of the fermi national accelerator Laboratory in Batavia, Ill., who heard collar’s talk. “everything that you would hope would be there, if it’s dark matter, is basically there.”

the finding does not constitute a discovery of dark matter, however, because the likelihood of such results appearing by chance are too high to qualify for what physicists consider proof, notes hooper.

wImPs are favoured candidates for dark matter particles because they have been predicted in theories attempting to unify nature’s known particles and forces. features predicted for wImPs correspond with properties expected for cosmic dark matter, the gravitational glue that holds galaxies together and allowed them to form in the first place (Sn: 8/28/10, p. 22).

If correct, the coGent result implies that wImPs have a relatively low mass, roughly five

winter, the earth’s revolution would take it in the opposite direction of the galaxy’s rotation. So detectors ought to see more collisions in northern summer than winter — the trend now seen by both dama/LIBra and coGent.

theorist neal weiner of new york University says his calculations indicate that the coGent team was either very lucky or saw an unusually high variation in the collision rate to be able to make a tentative detection with just 15 months of data.

theorists are now increasingly challenged to identify properties of dark matter that might explain why some experiments see signs of the particles while others do not, weiner said may 2 in Baltimore at a meeting on dark matter.

Signs of dark matter from Minnesota mine By nASA Science news

The CoGeNT detector during installation (image Pacific Northwest National Laboratory)


what does the universe look like?

by Simon Lowther

TiMe To PoP THe BALLoon!

as a young astronomer I often asked about the shape of the universe, and was always unsatisfied with the answers given; I did not know why. Later as a presenter to the public the same question was directed to me on a nightly basis, and I repeated the same explanations about curved space and balloons with dots on them. I have now come to realize that this concept of universe geometry is one of the most misunderstood, and the balloon analogy is one of the main reasons. It’s time to pop the balloon!

My BRAin ACHeS wiTH 4 diMenSionS!

Standing in a meadow one could satisfactorily argue that the earth is flat, and extends the same distance in all directions from where I am standing. we know that this is not the case, and that in fact the earth is nearly spherical (it is a bit squashed at the poles to be called perfectly round). Prior to christopher columbus persons understanding of the shape of the earth was limited by their own experience of the world, and so it was reasonable to make exertions about the earths flatness and madness to believe anything else. note 1

with understanding universal geometry we are also limited by our own experience of the world. we look forward and backward, left and right, up and down, and experience existence in 3 spatial dimensions; einstein has shown us that the universe probably exists in at least four. how could we visualize this 4-dimensional space? well you can’t, but we can express its properties using mathematics.

wHAT iS THe UniVeRSe?

there are two universes that cosmologists talk about. the first is the observable universe, and describes all that we can see or detect. Sometimes cosmologist will shorten the name of the observable universe to just the universe, which can cause confusion. the Universe is everything there is, and is larger than the observable universe. the observable universe is limited in size by the time it takes for light to travel; hence the universe can be larger depending on the model.

a common question is what is outside the universe, or what is the universe expanding into. this question is a result of the balloon

analogy, and demonstrates how our minds fail to visualize the geometry of space. the balloon is a two dimensional object expanding into three dimensional space, it does not mean that our three dimensional universe is expanding into 4-dimensional space. I know that this is a rather unsatisfying answer, but the reality is that no one can speak on what they can not see.

So How do we deSCRiBe A UniVeRSe?

cosmologists have several descriptors that they use to describe the properties that the universe has. first we can ask, is the universe finite or infinite? also we ask is it bounded or unbounded? these two questions seem to be the same thing, but they are not. a sphere has a finite shape and volume but an object travelling along its surface would never reach the end, so it is also unbounded.

cosmologists also describe the curvature of space. a universe which has no curvature is called flat. Parallel lines would remain parallel, and the angles in a triangle add up to 180 degrees. a positively curved universe has parallel lines that eventually move towards each other, and a triangle angles would add to more than 180 degrees; while negatively curved space has parallel lines which end up diverging, and triangles with internal angles summing to less than 180 degrees. curved universes are also described as closed, they are finite and unbounded; and could result in a big crunch. a flat universe is open, it will expand forever, but this expansion will tend towards zero. Unfortunately with all these descriptors we go back to school room shapes to visualize the concepts, it is important to remember that the universe probably encompasses four spatial dimensions.

How do THeSe fiT oUR UniVeRSe?

the biggest problem with trying to work out the geometry of the universe is that we are stuck in it. a similar problem existed with trying to work out the geometry of our galaxy; initial inspection from our location gives very little clues to its spiral nature. cosmologists infer the properties of the universe from observations of the way light travels through it, but at present most properties are best fit with little certainty. the best tool so far is observation of the early universe through observation of the cosmic microwave background (cmB). the wmaP (wilkinson microwave anisotropy Probe) was able to measure the flatness of the local universe which it found to be flat within 2%. astronomers are reasonably certain that the universe is flat, but even the wmaP scientists wouldn’t commit to it saying that it is also possible that the universe is curved with a radius beyond the detection limit of the probe.

It is hoped that the Planck probe will be sensitive enough to be able to not only work out the curvature (if any) of the universe, but also state with certainty whether it is finite or

Fig 1. Geometry of Universes

Fig 2. Hyperdodecahedran


This infrared image taken by nASA’s wide-field infrared Survey explorer, or wiSe, shows a star-forming cloud teeming with gas, dust and massive newborn stars. The inset reveals the very center of the cloud, a cluster of stars called nGC 3603. it was taken in visible light by nASA’s Hubble Space Telescope.

wiSe, which is surveying the whole sky in infrared light, is particularly sensitive to the warm dust that permeates star-forming clouds like this one. in this way, wiSe complements visible-light observations.

The mission also complements Hubble and other telescopes by showing the ‘big picture,” providing context for more detailed observations. for example, the wiSe picture here is 2,500 times larger than the Hubble inset. while the Hubble view shows the details of the hot young star cluster, the wiSe picture shows the effects that this stellar powerhouse has on its neighbourhood.

The cluster contains some of the most massive stars known. winds and radiation from the stars are evaporating and dispersing the cloud material from which they formed, warming the cold dust and gas surrounding the central nebula. This greenish “halo” of warm cloud material is seen best by wiSe due to its large field of view and improved sensitivity over past all-sky infrared surveys.

These wiSe observations provide circumstantial evidence that the massive stars in the center of the cluster triggered the formation of younger stars in the halo, which can be seen as red dots. The dust at the center of the cluster is very hot, producing copious amounts of infrared light, which results in the bright, yellow cores of the nebulosity.

Ultimately, this turbulent region will be blasted apart by supernova explosions. other star-forming clouds in the Milky way have experienced such eruptions, as evidenced by their pockmarked clouds of expanding cavities and bubbles.

Massive star clusters like this one are an important link to understanding the details of the violent original epoch of massive star formation in the early, distant universe. Astronomers also use them to study distant starbursts that occur when galaxies collide, lighting up tremendous firestorms of brilliant, but ephemeral, stars in the wreckage. Because nGC 3603 is so close, it is an excellent lab for the study of such faraway and momentous events.

in the wiSe image, infrared light of 3.4 and 4.6 microns is blue; 12-micron light is green; and 22-micron light is red.

nASA’s Jet Propulsion Laboratory, Pasadena, Calif., manages the wide-field infrared Survey explorer for nASA’s Science Mission directorate, washington. The mission’s principal investigator, edward wright, is at UCLA. The mission was competitively selected under nASA’s explorers Program managed by the Goddard Space flight Center, Greenbelt, Md. The science instrument was built by the Space dynamics Laboratory, Logan, Utah, and the spacecraft was built by Ball Aerospace & Technologies Corp., Boulder, Colo. Science operations and data processing take place at the infrared Processing and Analysis Center at the California institute of Technology in Pasadena. Caltech manages JPL for nASA.

infinite, and whether bounded or unbounded.

the current standard model (friedmann-Lemaître-robertson-walker) is used to estimate the shape of the observable universe. It assumes that the universe is on average homogenous and isotropic (though on small scales this is not the case). the determining factor as to whether the universe is open or closed is its density. above or below a critical value will result in a curved universe, either positively (sphere universe) or negatively (saddle universe). with the density being equal (or very close too) to the critical density, the universe will be flat.

ok So wHAT iS THe SHAPe?

there are several shapes that fit the current model of the universes properties, one of the most popular being the torus (doughnut). this does not mean that the universe is doughnut shaped, remember that we are fitting a three dimensional solution to a 4-dimensional problem. a sphere does not fit well with the wmaP data, but a Poincare dodecahedral space does, as well as a hyperbolic (negatively curved) horn topography. So the short answer

is that there are several shapes that could describe the universes shape.

yeah, but none of this helps in describing it to a young person

a better model of explaining expansion in the universe is that of raisin bread being baked in an oven. the bread is the universe, the raisins are the galaxies. as the loaf expands, all the raisins move away from each other. while this is not a perfect model (there are none, I’ve been looking for a while) it does do away with the expectation of a center and a surface as our universe has neither.

trying to describe the universe as a 4-dimensional doughnut shaped raisin loaf with no centre or edges may not go down too well though!

astronomers and cosmologists have an exciting task ahead of them, in unravelling the tangles of the universe, the fact it is so weird also makes it so wonderful. what may be even more exciting is then unravelling the tangles of science speak so that we all may enjoy the wonders of the universe.

note 1: It is a modern urban myth that the

people of the 15th century believed the earth

was flat, they knew it to be a sphere and had

plenty of evidence to support this. the myth was

popularized through 20th century literature.

christopher columbus’s disagreement with

scholars was only over the diameter of the

sphere and therefore the distance to India, not

whether or not he would fall off the earth.

Stellar Storm of infrared light

june 2011 society journal

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