Astronomy Night at theSussex County Amateur Radio Club

Welcome!

• This presentation came about due to the amount of interest in the topic of astronomy by club members

– After all we congregate and interact using radio waves

– Astronomers congregate and interact using light waves a few frequencies above our community’s wavelengths

What is Astronomy?

• Astronomy is a natural science which is the study of celestial objects

– Sun, Moon, Planets, Planetary moons

– Stars, Nebula, Clusters, Galaxies

• In other words- the known Universe in optical and non-optical wavelengths

– Ever hear of radio-astronomers?

Radio-Astronomers?!?

• Yes! Radio astronomy is a subfield of astronomy that studies celestial objects at radio frequencies.

Radio - Astronomers• Our Cousin HAMs ( in a sense) Radio

Astronomers see some pretty neat stuff!An optical image of the galaxy M87 (HST), a radio image of same galaxy using Interferometry (Very Large Array-VLA), and an image of the center section (VLBA) using a Very Long Baseline Array (Global VLBI) consisting of antennas in the US, Germany, Italy, Finland, Sweden and Spain. The jet of particles is suspected to be powered by a black hole in the center of the galaxy.

This is the primary difference between optical astronomy and radio astronomy.We glean different information from using different wavelengths

Radio / Optical - Astronomy

Radio - Astronomy

• Observations from the Earth's surface are limited to wavelengths that can pass through the atmosphere. At low frequencies, or long wavelengths, transmission is limited by the ionosphere, which reflects waves with frequencies less than its characteristic plasma frequency. Water vapor interferes with radio astronomy at higher frequencies, which has led to building radio observatories that conduct observations at millimeter wavelengths at very high and dry sites, in order to minimize the water vapor content in the line of sight. Finally, transmitting devices on earth may cause radio-frequency interference. Because of this, many radio observatories are built at remote places.

Astronomy

• Astronomy is one of the oldest sciences.

• Prehistoric cultures have left astronomical artifacts such as the Egyptian monuments and Nubian monuments, and early civilizations such as the Babylonians, Greeks, Chinese, Indians, Iranians and Maya performed methodical observations of the night sky.

• However, the invention of the telescope was required before astronomy was able to develop into a modern science.

• Historically, astronomy has included disciplines as diverse as astrometry, celestial navigation, observational astronomy and the making of calendars, but professional astronomy is nowadays often considered to be synonymous with astrophysics.

Star Maps

• Star maps have been around since man started looking at the night sky

– From culture to culture remarkably similar but each culture saw something different in the sky dependent on their “world view”

– For example the Greeks immortalized their heroes and villains in the night sky

– Orion

– Perseus

– Andromeda

– Hercules

– Cassiopeia

– Cepheus

Star Maps – Guideposts to the Stars

Star Maps – Guideposts to the Stars

• Sky charts provide “coordinates” that pinpoint a star’s address in the night sky.

– Stars stay located in the same area of the sky for most of our lifetimes

– That’s not to say they’ll be in the same location a million years from now. That happens due to the fact that everything is moving and expanding in the universe, so ten generations from now their positions relative to Earth would have moved.

Star Maps – Guideposts to the Stars

• Our night sky is really a clock

– Stars move around on sidereal time.

– Sidereal time is based on one rotation of the Earth in relation to any star

• Sidereal time is divided into 24 hours but the day itself is 4 minutes shorter

– How do find sidereal time?

• You can use a chart or a formula

Star Maps – Guideposts to the Stars

• So why is it important to know sidereal time?– Because you can calculate the appearance of a night sky

object. • You can also figure out trajectories – but not in this presentation!

– Start by figuring out what your local mean time is

• Local Mean time = Greenwich Mean time –Longitude west (your longitude in hours and minutes in time)– For example GMT= 12Hrs 00mins

Long = 5Hrs 26 mins

LMT= 6hr 34 min

Star Maps – Guideposts to the Stars

• Next Find your sidereal time– You’ll need to find a chart that tells you what Greenwich

Sidereal time is at 0hrs.

• Local Sidereal time = Local Mean time + Greenwich Sidereal time + (LMT /6) a correction factorLST = LMT + GST+(LMT/6)

Or go to http://www.jgiesen.de/astro/astroJS/siderealClock/

• So why is this important?– You’ll know when and where an object will come up over

the horizon but more importantly “navigate” your scope towards it in the night sky

Star Maps – Guideposts to the Stars

Optical Astronomy

• Optical Astronomy deals with what the human eye can see and some wavelengths we can’t see.

• Instead of using antennas and radio receivers professional and amateur astronomers use optical devices called telescopes to capture light, focus it, and create an image the human eye can see.

• Telescope – origins of the name – 1640s, from Italian telescopio (Galileo, 1611), and Modern Latin

telescopium (Kepler, 1613), both from Greek teleskopos "far-seeing," from tele- "far" (see tele-) + -skopos "watcher" (see scope (n.1)).

– Said to have been coined by Prince Cesi, founder and head of the Roman Academy of the Lincei (Galileo was a member). Used in English in Latin form from 1619.

Telescopes

• Most of us believe Galileo was the first person to create the telescope, and the invention of the telescope is largely attributed to him.– However…. Galileo was the first to use a telescope for the purpose of

astronomy in 1609 (400 years ago in 2009, which was celebrated as the International Year of Astronomy). Hans Lipperhey, a German spectacle maker, is generally credited as the inventor of the telescope, as his patent application is dated the earliest, on the 25th of September 1608.

Telescopes

• So essentially a telescope “receives” light waves (photons) at various optical frequencies

• Telescopes condition the light by magnification or wavelength separation

• We think of just amplifying the light by magnification, but when you look through a telescope’s lens your eye is receiving all the optical wavelengths including infrared, and ultraviolet wavelengths

Telescopes

• Types of telescopes

– Refractors , Reflectors, Complex

What to Use and How to Use it

• Just like HAMs have base stations, mobiles, portables, and handhelds….amateur astronomers have options as well, depending on what they want to do, and where they want to observe.

What to Use and How to Use it

• Some amateurs are interested only in objects nearby, and use refractors.

• Refractors will work fine, are relatively easy to set up, and will magnify sufficiently well to provide astonishing detail on the moon, or planets.

• The majority of good quality refractors will come with a “German equatorial mount”

• “Christmas scopes” have lower quality optics, and cheaper alt azimuth mounts.

What to Use and How to Use it

• Some amateurs are interested in “deep sky” and objects nearby.– All types of telescopes will work fine, however when viewing “deep

sky” objects you’ll need to capture more light, and magnification isn’t always the best way to observe

• SIZE MATTERS – to an extent, there’s limitations.• Reflectors using mirrors greater than 6 inches in diameter, generally

work best for weekend amateurs • Refractors will work as well, but the lenses will need to be higher

quality and made with more precision. – Apochromatic lenses will provide color correction

• Mounts can be equatorial, or alt azimuth.– Spending a little more on solid mounts is well worth the effort to

minimize vibration in the system

Alt- Azimuth Mounted Telescopes

These are great when you just want to go camping on a weekend, or step outside in your backyard and do visual observing

Equatorial Mounted Telescopes

These are great when you want to spend time outside “tracking” a sky object , doing imaging, or want the telescope to guide itself. Takes a little more time to set up, but well worth it!

Short Video

http://youtu.be/_TNrPLHB21k

The Night Sky

• Telescopes have evolved over the last 400+ years to a point where amateurs and professional astronomers have been able to collaborate and share observations and events.

• Basically for the first 300 years or so manually driven observation was the way astronomers viewed the night sky

• To do so they relied heavily on equatorial mounts since telescopes using those mounts could utilize precision gears, and weights to move the large telescopes they carried– Remember size matters?

Aperture Size and Light Gathering

• Objective diameter alone determines the light power of your telescope– That’s why size matters but…..

• All stars are “rated” by their star magnitude (relative brightness)– The star magnitude scale base is measured upon the un-aided human

eye’s ability to see the faintest star.

Aperture Size and Light Gathering

• On a scale of -2 to 24 the human eye can see a star with a magnitude of ~6.2mag so…

– There’s a brightness difference along the scale• A magnitude of 1 has a relative brightness of 100 ( 1st magnitude star like

Spica is rated 100)

• A 9th magnitude star is 100 times fainter!

– Telescopes have a limit on what light they can gather• A 6inch diameter Newtonian has a limit of magnitude 13.5

• A 12 inch 14.5

• The 200 inch Mt Palomar Telescope has a 20.5 magnitude limit.

– http://www.stargazing.net/david/constel/constel/ursaminor.html

Magnitude Needed to see an object of this brightness* Examples

-26 the sun

-13 full moon

-6 crescent moon

-4 naked eye: easy even from large cities planet Venus

-2 naked eye planet Jupiter

-1 naked eye Sirus brightest star,

0 naked eye: difficult if near bright summer evening star

artificial lights but generally Vega; C/1996 B2

visible even from large cities (Hyakutake) at peak

+1 naked eye: brilliant as seen from planet Saturn

dark, rural areas

+2 naked eye: difficult but visible from stars of Big Dipper

3 naked eye: rural, suburban, small city faintest naked-eye

binoculars: bright, urban areas stars visible from

4 naked eye: (outer) suburbs faintest naked-eye

binoculars: cities (stars), suburban stars visible from

areas (diffuse objects such as comets)

5 generally binocular objects from urban moons of Jupiter

and suburban areas; faintest naked-eye

stars visible from "dark" rural areas

located some 40 miles (60 km) from

major cities

What’s Up in the Night Sky?

• Planets– Mercury- hard to see

due to its proximity to the sun

– Venus – You don’t need a scope but if you do you’ll need filters

– Mars – What a gem!

– Jupiter – one of the neatest sights to see in the night sky

– Saturn – Spectacular

What’s Up in the Night Sky?

• Deep Sky

– Open Clusters

– Nebulas

– Galaxies

What’s Up in the Night Sky?

• Today we use software to make multiple digital exposures to spectacular images of what we see with our scopes!

Image taken from a 10 inch Newtonian scopeusing multiple exposures

Read more: http://www.universetoday.com/41889/who-invented-the-telescope/#ixzz39ExCEWjO

http://en.wikipedia.org/wiki/Magnitude_%28astronomy%29http://www.stargazing.net/david/constel/constel/ursaminor.htmlhttps://sites.google.com/site/greekastronomyabc/constellationshttp://www.jgiesen.de/astro/astroJS/siderealClock/http://www.astro.umd.edu/~jph/GST_eqn.pdf