stars and galaxies space science for middle school at hcde february 20, 2009 created by the lunar...
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Stars and GalaxiesStars and Galaxies
Space Science for Middle School at HCDESpace Science for Middle School at HCDE
February 20, 2009February 20, 2009
Created by the Lunar and Planetary InstituteFor Educational Use Only
LPI is not responsible for the waysin which this powerpoint may be used or altered.
Image at http://hubblesite.org/newscenter/archive/releases/galaxy/spiral/2009/07/image/g/results/50/
Welcome!Welcome!
Please complete the pre-assessmentPlease complete the pre-assessment It’s for us—it’s not about youIt’s for us—it’s not about you Please let us know how much YOU know, Please let us know how much YOU know,
not how much your friends sitting next to not how much your friends sitting next to you knowyou know
What are we going to cover?What are we going to cover?
Our Place in the UniverseOur Place in the Universe The Electromagnetic SpectrumThe Electromagnetic Spectrum Classifying StarsClassifying Stars Classifying GalaxiesClassifying Galaxies History of the UniverseHistory of the Universe
First up…First up…
Our Place in the UniverseOur Place in the Universe What is our Universe made of?What is our Universe made of? How big are things? How far away?How big are things? How far away? How do we know?How do we know?
What is our Universe made of?What is our Universe made of?
Stars and planetsStars and planets Gas and dustGas and dust Organized into star clustersOrganized into star clusters Organized into nebulaeOrganized into nebulae Organized into galaxiesOrganized into galaxies Other things:Other things:
Black holesBlack holes Dark matterDark matter Dark energyDark energy
What was in your drawing?What was in your drawing?
Image from http://galileo.rice.edu/lib/student_work/astronomy95/orionpleiades.html
Activity!!Activity!!
Use the Venn diagrams to place the stickersUse the Venn diagrams to place the stickers—where does everything go?—where does everything go?
After you’re finished, let’s discuss…After you’re finished, let’s discuss…
Examining the ComponentsExamining the Components
Stars Stars Gas and dust (Nebulae)Gas and dust (Nebulae)Star clustersStar clustersGalaxiesGalaxies
Different types of stars
Different types of stars
Image from http://hubblesite.org/newscenter/archive/releases/star%20cluster/globular/2003/21/image/a/results/50/
Types of StarsTypes of Stars
BigBig SmallSmall RedRed BlueBlue YellowYellow In groupsIn groups AloneAlone
More laterMore later
What is a “star cluster”?What is a “star cluster”?
stars formed together at same time
stars may be gravitationally bound together
two types: open (galactic) and globular
Image at http://hubblesite.org/newscenter/archive/releases/star%20cluster/globular/2007/18/image/a/format/web/results/50/
Open ClustersOpen Clusters
dozens to thousands of stars young stars! only a few
million years old may still be surrounded by
nebula from which they formed located in the spiral arms of a
galaxy example: Pleiades
Image at http://hubblesite.org/newscenter/archive/releases/star%20cluster/open/2004/20/image/a/results/50/
More open star clustersMore open star clusters
Image from http://hubblesite.org/newscenter/archive/releases/star%20cluster/open/2006/17/image/a/results/50/
Globular ClustersGlobular Clusters
millions to hundreds of millions of stars
old! 6 to 13 billion years mostly red giants and dwarfs stars are clumped closely together,
especially near the center of the cluster (densely)
surround our disk as a halo
Image at http://hubblesite.org/newscenter/archive/releases/star%20cluster/globular/1999/26/image/a/results/50/
What is a “nebula”?What is a “nebula”?
A cloud in spaceA cloud in space Made of gas and dust Made of gas and dust
Can have stars inside
Most of the ones we see are inside our Milky Way Most of the ones we see are inside our Milky Way GalaxyGalaxy
Different typesDifferent types
Orion image at http://hubblesite.org/newscenter/archive/releases/2006/01/image/a/results/50/
Large, massive, bright nebulaeLarge, massive, bright nebulae
Emission NebulaEmission Nebula•The hot gas is emitting lightThe hot gas is emitting light
Orion image at http://hubblesite.org/newscenter/archive/releases/2006/01/image/a/results/50/
Colder, darker nebulaeColder, darker nebulae
Dark dust blocking the hot Dark dust blocking the hot gas behind itgas behind it
NOAO/AURA/NSF Image from http://hubblesite.org/newscenter/archive/releases/nebula/dark/2001/12/image/c/results/50/
Leftovers from an ExplosionLeftovers from an Explosion
Supernova remnantSupernova remnant (smaller, less gas) (smaller, less gas)
Image at http://hubblesite.org/newscenter/archive/releases/nebula/supernova-remnant/2005/37/results/50/
What is a “galaxy”?What is a “galaxy”?
A large group of stars outside of our own Milky WayA large group of stars outside of our own Milky Way Made of billions to trillions of starsMade of billions to trillions of stars
Also may have gas and dust Also may have gas and dust
Spiral, or elliptical, or irregular shapedSpiral, or elliptical, or irregular shapedImage at http://hubblesite.org/newscenter/archive/releases/galaxy/spiral/2007/41/results/50/
Spiral galaxy--AndromedaSpiral galaxy--Andromeda
NOAO/AURA/NSF Images at http://www.noao.edu/image_gallery/html/im0606.html and http://www.noao.edu/image_gallery/html/im0685.html
Elliptical GalaxiesElliptical Galaxies
Images at http://hubblesite.org/newscenter/archive/releases/galaxy/elliptical/2007/08/image/a/format/large_web/results/50/ and http://hubblesite.org/newscenter/archive/releases/galaxy/elliptical/1995/07/results/50/
Irregular GalaxiesIrregular Galaxies
NASA and NOAO/AURA/NSF Images at http://hubblesite.org/newscenter/archive/releases/galaxy/irregular/2005/09/results/50/ , http://www.noao.edu/image_gallery/html/im0560.html , and http://www.noao.edu/image_gallery/html/im0993.html
Our Galaxy: the Milky WayOur Galaxy: the Milky Way
has about 200 billion stars, and lots of gas and dust
is a barred-spiral (we think) about 100,000 light-years wide our Sun is halfway to the edge, revolving at
half a million miles per hour around the center of the Galaxy
takes our Solar System about 200 million years to revolve once around our galaxy
The Milky WayThe Milky Way
Image at http://news.nationalgeographic.com/news/bigphotos/1945371.html
Mapping the Milky WayMapping the Milky Way
We can see stars We can see stars star clustersstar clusters nebulaenebulae GalaxiesGalaxies
Let’s try to Map our GalaxyLet’s try to Map our Galaxy
How do we know what our Galaxy How do we know what our Galaxy looks like?looks like?
Measuring DistancesMeasuring Distances
Parallax (let’s model it)Parallax (let’s model it) As Earth orbits the Sun, we see nearby stars move relative to more distant stars
How many degrees did the plate move, relative to the background?
Can you calculate the distance to the plate?
Sine of the parallax (angle) x Earth’s distance to the Sun = Distance to the star
The angles involved for strellar observations are very small and difficult to measure. Proxima Centauri, has a parallax of 0.77 arcsec. This angle is approximately the angle subtended by an object about 2 centimeters in diameter located about 5.3 kilometers away.
Measuring DistancesMeasuring Distances
What is a Light Year?What is a Light Year? A light year is the distance light travels in a year. Light moves at a A light year is the distance light travels in a year. Light moves at a
velocity of about 300,000 kilometers (km) each second; how far velocity of about 300,000 kilometers (km) each second; how far would it move in a year?would it move in a year?
About 10 trillion km (or about 6 trillion miles).About 10 trillion km (or about 6 trillion miles).
Why do we use light years?Why do we use light years? Show me how far 5 centimeters is.Show me how far 5 centimeters is. Now show me 50 centimeters.Now show me 50 centimeters. Now tell me (without thinking about it, or calculating it in meters) how far Now tell me (without thinking about it, or calculating it in meters) how far
500 centemeters is. 2000? 20,000?500 centemeters is. 2000? 20,000? We need numbers that make sense to us in relationship to objects; we We need numbers that make sense to us in relationship to objects; we
scale up and use meters and kilometers for large numbers.scale up and use meters and kilometers for large numbers.
Time for a Break! Next UpTime for a Break! Next Up
Our Place in the UniverseOur Place in the Universe The Electromagnetic SpectrumThe Electromagnetic Spectrum Classifying StarsClassifying Stars Classifying GalaxiesClassifying Galaxies History of the UniverseHistory of the Universe
Let’s check your knowledgeLet’s check your knowledge
Please draw an electromagnetic spectrum Please draw an electromagnetic spectrum on a sheet of paper, and label the parts.on a sheet of paper, and label the parts.
You can work in groups.You can work in groups.
RadiationRadiation
There are lots of types of light (radiation), There are lots of types of light (radiation), including visible and invisibleincluding visible and invisible
Electromagnetic spectrum
http://coolcosmos.ipac.caltech.edu/cosmic_classroom/ir_tutorial/what_is_ir.html
.
Let’s Observe A SpectrumLet’s Observe A Spectrum
What will the spectrum look like with a red What will the spectrum look like with a red filter in front of your eyes? A blue filter?filter in front of your eyes? A blue filter?
Hypothesize and test your hypothesis.Hypothesize and test your hypothesis.
Now let’s examine the invisible parts—Now let’s examine the invisible parts—using our cell phones and a solar cell.using our cell phones and a solar cell.
There are different types of spectraThere are different types of spectra
ContinuousContinuous Emission or Bright Line (from ionized gas, like Emission or Bright Line (from ionized gas, like
a nebula or a neon sign)a nebula or a neon sign) Absorption or dark line (from stars)Absorption or dark line (from stars)
Illustration at http://imagine.gsfc.nasa.gov/docs/science/how_l1/spectra.html
RadiationRadiation
All stars emit radiationAll stars emit radiation Radio, infrared, visible, ultraviolet, x-ray and even some gamma Radio, infrared, visible, ultraviolet, x-ray and even some gamma
raysrays Most sunlight is yellow-green visible light or close to itMost sunlight is yellow-green visible light or close to it
The Sun at X-ray wavelengths
Image at http://imagine.gsfc.nasa.gov/docs/science/know_l1/sun.html
Image and info at http://imagine.gsfc.nasa.gov/docs/teachers/gammaraybursts/imagine/page18.html
.
Using a Star’s SpectrumUsing a Star’s Spectrum
We can use a star’s spectrum to classify it.We can use a star’s spectrum to classify it.
NOAO/AURA/NSF image at http://antwrp.gsfc.nasa.gov/apod/ap010530.html
Stellar EvolutionStellar Evolution
Time to Create a Stellar GraphTime to Create a Stellar Graph
Everyone will receive several “stars”Everyone will receive several “stars” Place them on the large paper, according to Place them on the large paper, according to
their color and their brightnesstheir color and their brightness This is a version of the Hertzsprung-Russell This is a version of the Hertzsprung-Russell
diagram.diagram.
Hertzsprung-Russell DiagramHertzsprung-Russell Diagram
Images from http://www.nasa.gov/centers/goddard/news/topstory/2007/spectrum_plants.html and http://sunearthday.gsfc.nasa.gov/2009/TTT/65_surfacetemp.php
Young stars form in nebulae
from Small Magellanic Cloud
Young stars form in nebulae
from Small Magellanic Cloud
Image at http://hubblesite.org/newscenter/archive/releases/2007/04/image/a/results/50/
Star-forming region in the Large Magellanic Cloud: http://hubblesite.org/newscenter/archive/releases/2008/31/image/a/results/50/
Orion image at http://hubblesite.org/newscenter/archive/releases/2006/01/image/a/results/50/
Interstellar “eggs”Interstellar “eggs”
Movie at http://www.stsci.edu/EPA/PR/95/44/M16.mpg
Our Sun is a Regular/ Small StarOur Sun is a Regular/ Small Star
Image at http://www.gsfc.nasa.gov/topstory/20011210insidesun.html
On the “Main Sequence”On the “Main Sequence”
In a few Billion years… Red GiantIn a few Billion years… Red Giant
Image at http://hubblesite.org/newscenter/archive/releases/1997/26/image/a/
Our Sun’s Habitable ZoneOur Sun’s Habitable Zone
Billions of years ago, things may have Billions of years ago, things may have been differentbeen different The Sun was cooler (by up to 30%!)The Sun was cooler (by up to 30%!) Earth’s atmosphere was different (thicker, Earth’s atmosphere was different (thicker,
carbon dioxide)carbon dioxide)
Conditions will be different in the Conditions will be different in the futurefuture By many accounts, increases in the Sun’s By many accounts, increases in the Sun’s
temperature will make Earth uninhabitable in temperature will make Earth uninhabitable in 1 billion years or less1 billion years or less
These changes will also affect other planets… These changes will also affect other planets… Mars?Mars?
Animation at http://www.nasa.gov/97994main_BHabitableZone.MPG
By 5 billion years… White DwarfBy 5 billion years… White Dwarf
Image at http://hubblesite.org/newscenter/archive/releases/nebula/planetary/1998/39/results/50/
Small, but very hotSmall, but very hot
Image at http://hubblesite.org/newscenter/archive/releases/nebula/planetary/2000/28/image/a/format/web_print/results/50/
Image at http://hubblesite.org/newscenter/archive/releases/nebula/planetary/2004/27/image/a/format/large_web/results/50/
Massive Stars are different
Massive Stars are different
Image from http://hubblesite.org/newscenter/archive/releases/nebula/emission/1997/33/results/50/
On the “Main On the “Main Sequence” but Sequence” but not for longnot for long
Image from http://hubblesite.org/newscenter/archive/releases/star/massive%20star/1996/04/image/a/results/50/
Betelgeuse—Red SupergiantBetelgeuse—Red Supergiant
Supernova—Massive Star ExplodesSupernova—Massive Star Explodes
Images at
http://hubblesite.org/newscenter/archive/releases/star/supernova/2004/09/results/50/ http://hubblesite.org/newscenter/archive/releases/nebula/supernova-remnant/2005/37/results/50/
http://chandra.harvard.edu/photo/2009/casa/
Neutron Star or PulsarNeutron Star or Pulsar
Image at http://hubblesite.org/newscenter/archive/releases/nebula/supernova-remnant/2002/24/results/50/
Black HoleBlack Hole
Image at http://hubblesite.org/newscenter/archive/releases/2002/30/image/a/results/50/
Classifying GalaxiesClassifying Galaxies
GalaxiesGalaxies
come in different sizes (dwarf, large, giant) come in different shapes and classifications
SpiralsEllipticalsLenticulars Irregulars
are fairly close together, relative to their sizes
Spiral GalaxiesSpiral Galaxies
have flat disk, spiral arms, central bulge, and a surrounding halo
some have a “barred” bulge are fairly large (no dwarf spirals) have lots of gas and dust and younger stars in their
arms, but older stars and little gas or dust in their halos and central bulges
GalaxiesGalaxies
Image at http://hubblesite.org/newscenter/archive/releases/galaxy/spiral/2005/01/results/50/
Spiral galaxy--AndromedaSpiral galaxy--Andromeda
NOAO/AURA/NSF Images at http://www.noao.edu/image_gallery/html/im0606.html and http://www.noao.edu/image_gallery/html/im0685.html
Spiral Galaxy on Edge
Spiral Galaxy on Edge
Image at http://hubblesite.org/newscenter/archive/releases/galaxy/spiral/2006/24/image/a/results/50/
Image at http://hubblesite.org/newscenter/archive/releases/galaxy/spiral/2007/41/results/50/
Elliptical galaxiesElliptical galaxies
range from spherical to football shaped range from very small to giant have very little gas or dust mostly old stars similar to the central bulge of a spiral galaxy
Elliptical GalaxiesElliptical Galaxies
Images at http://hubblesite.org/newscenter/archive/releases/galaxy/elliptical/2007/08/image/a/format/large_web/results/50/ and http://hubblesite.org/newscenter/archive/releases/galaxy/elliptical/1995/07/results/50/
LenticularLenticular
have a disk but no arms have little or no excess gas and dust
Image at http://hubblesite.org/newscenter/archive/releases/galaxy/elliptical/2002/07/results/50/
Irregular GalaxiesIrregular Galaxies
any galaxy that isn’t a Spiral, Elliptical, or Lenticular
usually have lots of gas and dust and young stars
may have a distorted shape from interaction with another galaxy
Irregular GalaxiesIrregular Galaxies
NASA and NOAO/AURA/NSF Images at http://hubblesite.org/newscenter/archive/releases/galaxy/irregular/2005/09/results/50/ , http://www.noao.edu/image_gallery/html/im0560.html , and http://www.noao.edu/image_gallery/html/im0993.html
Collisions!Collisions!
We now think that galaxies in groups and We now think that galaxies in groups and clusters often collideclusters often collide
The Milky Way is moving at 300,000 mph The Milky Way is moving at 300,000 mph toward the Andromeda Galaxytoward the Andromeda Galaxy
They may collide in about 5 billion yearsThey may collide in about 5 billion years Stars don’t usually collideStars don’t usually collide New orbits, gas piles up to form new starsNew orbits, gas piles up to form new stars
InteractingInteracting
Image from http://hubblesite.org/newscenter/archive/releases/galaxy/interacting/2000/34/results/50/
the Antennae or Micethe Antennae or Mice
Information at http://hubblesite.org/newscenter/archive/releases/galaxy/interacting/1997/34/results/50/
Images from http://hubblesite.org/newscenter/archive/releases/galaxy/spiral/2002/21/image/a/results/50/ and http://hubblesite.org/newscenter/archive/releases/galaxy/spiral/1999/16/image/a/results/50/
The occasional results of two The occasional results of two galaxies colliding: ringed galaxies colliding: ringed galaxies galaxies
Various galaxies (can you identify types?)
Various galaxies (can you identify types?)
Image at http://hubblesite.org/newscenter/archive/releases/galaxy/cluster/1999/31/results/50/
Supermassive black holesSupermassive black holes
almost every medium to large galaxy we’ve check has a supermassive black hole at the center
the larger the galaxy, the more massive the black hole
we don’t know which comes first, the galaxy or the black hole
we think that these black holes are responsible for some of the galaxies with jets and lobes which give off radio waves, x-rays, etc.
Active galaxyActive galaxy
Image at http://hubblesite.org/newscenter/archive/releases/galaxy/spiral/2000/37/results/50/
at the center of a large galaxyat the center of a large galaxy
Image at http://hubblesite.org/newscenter/archive/releases/exotic/black-hole/1998/22/results/20/ and
http://hubblesite.org/newscenter/archive/releases/exotic/black%20hole/2000/21/image/a/format/web_print/results/20/
Galaxy ClustersGalaxy Clusters
the Local Group includes the Milky Way, the Andromeda, and over
30 other smaller galaxies the Virgo Cluster
hundreds to thousands of galaxies, 60 million light-years away
giant elliptical at center, formed by galactic cannibalism
the Local Group is “falling” toward the Virgo Cluster at 60 to 250 miles per second!
Coma ClusterComa Cluster
Image at Image at http://hubblesite.org/newscenter/archive/releases/galaxy/cluster/2008/24/image/a/results/20/http://hubblesite.org/newscenter/archive/releases/galaxy/cluster/2008/24/image/a/results/20/
Superclusters!Superclusters!
clusters are bound together in larger structures, called superclusters
these superclusters have been mapped, and are grouped into long strings 300 million to a billion light-years long 100 to 300 million light-years wide and only 10 to 30 million light-years thick
in between these strings are huge voids of galaxies, although some astronomers may have detected hot gas
Evolution of GalaxiesEvolution of Galaxies
Image at http://www.galex.caltech.edu/media/glx2007-05f_img01.html
Origin of the Universe
Big BangBig Bang
Dominant scientific theory about the origin of Dominant scientific theory about the origin of the universethe universe
Occurred ~13.7 billion years agoOccurred ~13.7 billion years ago
What is the Big Bang?What is the Big Bang?
How do we know?How do we know?
What is the Big Bang?What is the Big Bang?
Infinitely dense point Infinitely dense point not governed by our not governed by our physical laws or timephysical laws or time
All matter and energy All matter and energy contained in one pointcontained in one point
Image from Image from http://www.newscientist.com/articleimages/dn11799/0-did-antimatter-factory-spark-brightest-supernova.html
Building a UniverseBuilding a Universe
Instantaneous filling of Instantaneous filling of space with all matterspace with all matter
History of the UniverseHistory of the Universe
•10-43 seconds - gravity separates from other forces
•10-35 to 10-32 seconds - fundamental particles - quarks and electrons
•10-6 seconds - quarks combine into protons and neutrons
•1 second - electromagnetic and weak nuclear forces separate
•3 minutes - protons and neutrons combine into atomic nuclei
•105 years - electrons join nuclei to make atoms; light is emitted
•105-109 years - matter collapses into clouds, making galaxies and stars
Orion Nebula - http://stardate.utexas.edu/resources/ssguide/planet_form.html
History of the UniverseHistory of the Universe
Image from Image from http://dsc.discovery.com/space/top-10/strange-universe/space-10-weirdest-things-universe-10.html
Later HistoryLater History
Image at http://www.galex.caltech.edu/media/glx2004-01r_img02.html
Big Bang TheoryBig Bang Theory
Image at Image at http://map.gsfc.nasa.gov/universe/bb_theory.html
In 1915, Albert Einstein concluded that the universe could not be static based on his recently-discovered theory of relativity and added a "cosmological constant" to the dded a "cosmological constant" to the theory of relativity because astronomers theory of relativity because astronomers assured him that the universe was staticassured him that the universe was static
Aleksandr Friedmann and Abbe George Aleksandr Friedmann and Abbe George LeMaitre are credited with developing the LeMaitre are credited with developing the basics of the Big Bang model between 1922 basics of the Big Bang model between 1922 and 1927; their calculations suggested that and 1927; their calculations suggested that universe is expandinguniverse is expanding, not static., not static.
Years later, Einstein called his cosmological Years later, Einstein called his cosmological constant the constant the biggest mistake of his careerbiggest mistake of his career
Expanding UniverseExpanding Universe
In 1929, Edwin Hubble showed that most In 1929, Edwin Hubble showed that most galaxies are red-shifted (moving away galaxies are red-shifted (moving away from us), and that a galaxy’s velocity is from us), and that a galaxy’s velocity is proportional to its distance (galaxies that proportional to its distance (galaxies that are twice as far from us move twice as are twice as far from us move twice as fast)fast)
Image from http://imagine.gsfc.nasa.gov/docs/science/mysteries_l1/origin_destiny.html
Hubble’s EvidenceHubble’s Evidence
Doppler shifting - wavelength emitted by something moving away Doppler shifting - wavelength emitted by something moving away from us is shifted to a lower frequencyfrom us is shifted to a lower frequency
Sound of a fire truck siren - pitch of the siren is higher as the fire Sound of a fire truck siren - pitch of the siren is higher as the fire truck moves towards you, and lower as it moves away from you truck moves towards you, and lower as it moves away from you
Visible wavelengths emitted by objects moving away from us are Visible wavelengths emitted by objects moving away from us are shifted towards the red part of the visible spectrumshifted towards the red part of the visible spectrum
The faster they move away from us, the more they are redshifted. The faster they move away from us, the more they are redshifted. Thus, redshift is a reasonable way to measure the speed of an Thus, redshift is a reasonable way to measure the speed of an object.object.
When we observe the redshift of galaxies, almost every galaxy When we observe the redshift of galaxies, almost every galaxy appears to be moving away from us – the Universe is expanding. appears to be moving away from us – the Universe is expanding.
Predictions for the Big Bang ModelPredictions for the Big Bang Model
The expansion of the Universe Edwin Hubble's 1929 observation that galaxies were generally Edwin Hubble's 1929 observation that galaxies were generally
receding from us provided the first clue that the Big Bang theory receding from us provided the first clue that the Big Bang theory might be right. might be right.
The abundance of the light elements H, He, Li The Big Bang theory predicts that these light elements should have The Big Bang theory predicts that these light elements should have
been fused from protons and neutrons in the first few minutes after been fused from protons and neutrons in the first few minutes after the Big Bang. the Big Bang.
The cosmic microwave background (CMB) radiation The early universe should have been very hot. The cosmic The early universe should have been very hot. The cosmic
microwave background radiation is the remnant heat leftover from microwave background radiation is the remnant heat leftover from the Big Bang. the Big Bang.
Evidence for Big BangEvidence for Big Bang
Red shiftRed shift - as light from distant galaxies approach earth there is an - as light from distant galaxies approach earth there is an increase of space between earth and the galaxy, which leads to increase of space between earth and the galaxy, which leads to wavelengths being stretchedwavelengths being stretched
In 1964, Arno Penzias and Robert Wilson, discovered a noise of In 1964, Arno Penzias and Robert Wilson, discovered a noise of extraterrestrial origin that came from all directions at once - extraterrestrial origin that came from all directions at once - radiationradiation left left over from the Big Bangover from the Big Bang
In June 1995, scientists detected In June 1995, scientists detected heliumhelium in the far reaches of the universe in the far reaches of the universe - consistent with an important aspect of the Big Bang theory that a - consistent with an important aspect of the Big Bang theory that a mixture of hydrogen (75%) and helium (25%) was created at the mixture of hydrogen (75%) and helium (25%) was created at the beginning of the universebeginning of the universe
When Did the Universe Form?When Did the Universe Form?
~13.7 billion years ago ~13.7 billion years ago
How do we know? How do we know? Spreading (Red Shift)Spreading (Red Shift) - -
know distances, rates of know distances, rates of
retreat, relative positionsretreat, relative positions Pervasive Pervasive background background
radiationradiation of 2.7°C above of 2.7°C above absolute zeroabsolute zero - afterglow - afterglow of the Big Bangof the Big Bang
http://timeline.aps.org/APS/resources/85_06a.jpg
Cosmic background radiation temperature on celestial sphere
Feedback, QuestionsFeedback, Questions
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