Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.atmob.org/library/member/brewster/whittierstarparty.pdf Дата изменения: Tue May 29 17:51:31 2007 Дата индексирования: Mon Oct 1 21:41:49 2012 Кодировка: Поисковые слова: tethys

Whittier School Star Party
Presented by Amateur Telescope Makers of Boston (ATMoB) and the North Shore Amateur Astronomy Club (NSAAC) in conjunction with Project Astro - Nov 19th (rain date Nov 24th)
For more information:
ATMoB: http://www.atmob.org NSAAC: http://www.star.net/people/~nsaac Project Astro: http://www.aspsky.org
This guide written by Brewster LaMacchia, member ATMoB/NSAAC
Project Astro is sponsored by the Astronomical Society of the Pacific with the support of the National Science Foundation and NASA. In the Boston area, project Ast ro is spons ored by the Museum of Science and the Smithsonian Astrophysical Observatory at Harvard University

1.0 Observing - planets
Close one eye (use your hand if it's easier) and look straight down into the eyepiece. The most sensitive spot o your eye is slightly off center (Why? ____________________) - using what astronomer's call `averted vision' you will see more (but it takes practice). Jupiter, Saturn and their moons. Use the chart on the next page to identify the moons, how many can you see (depending on the telescope, the image may be inverted, flipped, or both). Jupiter _____. Saturn ____. Look for the horizontal bands of clouds on Jupiter - how many different ones can you see? _________. What colors are they? __________ The colors of objects help scientists determine what something is made of. (more precisely: what something is NOT made of. Why?_______________). Do any of the moons have a different color Which ones? _________________.

2.0 Observing - stars
With stars, the color of their surface (called the photosphere) is directly related to their temperature. This in turn can help scientist determine the mass of a star. What color are the coolest stars? ________ The hottest? _______. The human eye is most sensitive in the yellow-green area, which is close to the `yellow' color of our sun. If we had evolved on a planet around a massive star, what `color' would our eye's see best? __________. Stars spend 95% of their lives converting hydrogen to helium via nuclear fusion deep in their cores (why not at th surface? __________), which releases energy. Massive stars use up their fuel much faster - in some cases less than 100 million years. Small red dwarfs, on the other hand, are believed to be able to last for 100's of billions of years. Based on how evolution took place on Earth, why is it unlikely that life would exist around massive stars? _______ How old is our sun, and when will it run out of hydrogen? _____ _____.

3.0 Observing - clusters and galaxies
Open clusters are formed when a large cloud of galactic gas (up to dozens of light years across) condenses to form dozens or hundreds of stars at once. Open clusters orbit the galactic center in the same plane as the other stars and eventually drift apart. The ones you may see tonight range from several hundred light years away (Pleiades) to almost ten thousand (double cluster in Perseus). Globular clusters are larger groupings (tens of thousands to a mil lion) of stars that formed outside of the galaxy and `orbit' around the center of the galaxy. The ones you may se tonight range from 20,000 to 60,000 light years away. Galaxies are large groupings of stars containing millions to hundreds of billions of stars. Our own Milky Way gal axy is somewhat flat with a spiral shape and a bulge in the middle. The Milky Way is about 75,000 light years in diameter and averages 3000 light years in thickness (outside the center bulge). The Andromeda Galaxy (M31) is very similar to our own and is the most distant object that can be seen with the naked eye (a little over 2 million light years away). From the light polluted suburbs of Boston we can only see the central portion. Very large telescopes are needed to make out individual stars.

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In addition to Earth ls, galaxies haveMoon ical and irregular shapes, but detail is only visible in photographs. spira ellipt
Callisto Europa Io Ganymede

Thurs 11/19

Star
Europa Callisto Ganymede Io

JUPITER Tues 11/24
Jupiter and moons shown with Earth and its moon for comparison

East

West

Thurs 11/19
Enceladus Mimas Titan Dione Rhea Tethys
Earth Moon

Hyperion

SATURN
Iapetus Rhea Enceladus
Saturn diagrams shown magnified 2.5 times relative to the Jupiter drawings to account for Saturn's greater distance from Earth. Saturn is 60% the diameter of Jupiter. Earth and moon shown for comparison.

Tethys Mimas Dione

Tues 11/24

Titan

Relative moon sizes
Moons arranged left to right in order of increasing distance from planet.

Earth's moon 3476 km

Io 3632 km

Europa 3126 km Ganymede 5276 km

Callisto 4820 km

Mimas 390 km

Enceladus 510 km

Tethys 1050 km

Dione 1120 km

Rhea 1530 km Titan 5150 km

Hyperion 400 x 250 x Iapetus 1,440 km 200 km
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4.0 Star Chart
The star chart below is correct for 7PM on marked with the direction you are facing is center of the map is directly overhead. Try projection used to make this map makes th those near the horizon. Nov 20th and 6PM for mid-December. Turn down. The stars on the horizon should look and identify the brighter stars (bigger dots o e constellation size on the map look smaller the map so that the edg like those on the map. Th n map) first. Note that th for ones overhead versus

The Milky Way is not shown but runs from horizon to horizon through Auriga, Perseus, Cassopeia, and Aquila.

DRACO

Deneb

CYGNUS

Vega

CETUS

PISCES

AQUARIUS

Fomalhaut

CAPRICORNUS

Whittier School Star Party

AQUILLA

Altair

PEGASUS

LYRA

HERCULES

URSA MINOR CEPHEUS
Polaris

URSA MAJOR
Capella

CASSIOPEIA

PERSEUS

AURIGA
Aldebaran Pleiadies

TAURUS

ANDROMEDA

M31

ARIES

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5.0 Solar System Model
Off to the side of the observing area a solar system model has been set up. Please do not touch any of the stakes as they are easy to knock over. The scale of the model is roughly correct ONLY for the spacing between planets, the scale is one centimeter = one million kilometers (1" = 1.6 million miles). At this scale the sun would be a spher 1.4 cm in diameter - the size of a large marble. The earth would be a spec the size of a grain of sand. The model uses the same size balls for all planets, and a larger one for the sun. Note that the positioning is only approximate. Only planets visible to the naked eye are lit. The model is oriented in the same general positions as found the night of the star party. To use the model stand nea the Earth post and look towards the sun. This corresponds to noon with sun `directly' overhead (actually, you would have to angle your head 45 degrees to correspond with our latitude). Turn 90 degrees counter clockwise - it is now 6PM. Turn another 90 degrees so the sun is directly behind you - it is now midnight. Turn another 90 degrees counter clockwise and it is 6AM. What planets are never visible at midnight? _______ _______. Walk around the solar system and see what the view would be like from other planets.
TA BLE 1. Planetary inf Distance from sun (M km) 58 108 150 228 778 1427 2869 4497 5900 Orbital period (years) .24 .62 1 1.88 11.9 29.5 84 165 248

Planet Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto

6.0 Light Pollution

Full cut off vs. bad street lights

Light pollution is a problem in just about all urban and suburban areas. Broadly defined, light pollution is unwanted or wasted light, and comes from street lights, businesses, and private residences. It's estimated that in the US alone over $1 billion/year is wasted in this manner (and half of this amount is your tax dollars for street lights). Bad lighting presents a driving hazard (glare), more so for older drivers. Poorly designed outdoor lighting actually decreases security, and there is little data to suggest that excessive lighting makes anything safer - at best it only addresses our silly and ages old fear of the dark. The night sky is one of the most magnificent natural wonders that can be shared by all of mankind - yet light pollution has needlessly ruined the view for most of the population. In simple terms, any outdoor lighting fixture that you can see the bulb in is a badly designed (or installed) fixture. Try walking outside at night shining a flashlight directly in your face and you'll see why. Light that goes out sideways (or up!) represents wasted light (and therefor wasted $). The solution is simple - use what are called full cutoff light fixtures. At home, use sensor lights that only come o ne when someone is present. The electricity saved more than makes up for the slightly higher price of the fixture, and this style of lighting has a higher `security value. For more information see http://www.darksky.org.

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