Getting Started in Astronomy - the Absolute Basics
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by Paul J. Grim South East Ohio Astronomical Society http://www.athensastronomy.org/ July 2009 April, 2010 December 2011 |
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Equipment
All you need to see the night sky is your unaided (naked) eyes - telescopes and binoculars are not needed. Once you learn some of the basic stars and constellations, binoculars are very useful. If you become hooked on observing the night sky (in other words, you become an amateur astronomer), you might want to buy a small, good quality, light-weight telescope that is easily transportable.
Use a planisphere: This will show the location of the stars and constellations for the hour and date that you observe the night sky. For camping you might want to consider a small one such as the 8.5-inch square cardboard Star and Planet Locator made by Edmund Scientific for about $4. A larger planisphere, available online and in many bookstores, such as the 16-inch diameter plastic Guide to the Stars by David Levy (available for about $20), gives more details about the night sky. See image below.
Use binoculars to see stars and many more celestial objects such as star clusters, the Milky Way, nebulae, galaxies, double stars, and Solar System objects including the planets and the Moon.
One of the best books for beginning to learn about observational astronomy is Terence Dickinson's Nightwatch (about $20 - $25). It is available online and at many bookstores.
A good and inexpensive book is "Stars", a Golden Guide from St. Martin's Press authored by Herbert Zim and Robert Baker. The price is about $7.
A useful tool when observing with others is a 5mw green laser pointer, which can be used to point a thin, intense beam of light directly at stars and others objects (e.g., the locations of nebulae or galaxies). However, green lasers can harm your eyes if not used carefully. Children should not use them. And these should never be pointed at people or aircraft. They are widely available online for as little as $25 or less. Just google "green laser pointer" and you will find many sources for obtaining one.
Getting Help from Others: Star Parties and Astronomy Clubs
You will learn the night sky much quicker if you can get the help of one or more knowledeable amateur astronomers. This could be your next door neighbor who, if she or he knows the sky, will most likely be delighted to help you identify stars, constellations, and other objects in the sky.
All large cities and many smaller ones have astronomy clubs and will welcome you to join. Often such clubs (or societies) will have monthly meetings, which will feature talks on astronomy and also one or more nights in a month when members go to "dark locations" away from city light pollution in order to look at the sky, use their telescopes, and do astrophotography. In some cases there is no formal organization but just a bunch of guys and gals who meet at a good site on a weekly basis to observe the sky. Ask around and you may find such a group.
Then there are all types of star parties. These may involve small groups who meet for several hours after sunset in suburban settings and and are guided by a member of the local astronomy club with the use of a green laser pointer. There are larger more organized star parties, which may meet for a several days to a week in a place where camping is available.
A list of organizations including clubs, societies, planetariums, and observatories can be obtained here
There are major and minor star parties. Click here to see many of these. But for most, green laser pointers are not allowed. However, you might want to bring your pointer with you, because at many of the parties amateurs use them anyway, especially in the wee hours of the morning.
What to Look For
For beginners, all you need are your eyes and good observing conditions (clear skies and good atmospheric conditions, little interference from bright moonlight, and a minimum of light pollution - there is more on light pollution at the end of this article).
You can get an online prediction of viewing conditions by visiting the Clear Sky Chart website. This website has 48 hour viewing and weather predictions for hundreds of locations in Canada and the U.S. This site, used by amateur astronomers in the US and southern Canada, has been developed by Atilla Danko using data supplied by Environment Canada (Environnement Canada). An example of the results for Athens Ohio is given in the following image (when you go to the site, the meanings of such things as color, darkness, cloud cover, and transparency are given):
Remember that the stars and constellations you see depend on the season and the time of night that you observe. This is why a planisphere is so helpful. Also, some stars, visible in the Southern Hemisphere, are never visible from most of the U.S. and Canada. In Athens, for example, we cannot see such famous asterisms and stars as the Southern Cross and the Solar System's closest neighboring star, Alpha Centauri.
You should be able to identify the following stars, constellations, and asterisms. Asterisms? An asterism is generally a grouping of stars contained in a constellation which is much larger than the asterism. For example, the Big Dipper is an asterism in the constellation Ursa Major (the Greater Bear). On the other hand, bright stars from different constellations may form asterisms such as the Summer Triangle.
The following are major features for naked eye viewing from mid latitudes in the Northern Hemisphere. Comments are in parentheses. Constellation names are shown in bold. Prominent star names are NOT shown in bold. All can be easily located. There are many more but these are some of the best ones to know:
* Big Dipper (asterism in Ursa Major. It has two pointer stars pointing to the North Star)
* Arcturus (follow curvature of Big Dipper's handle to see this)
* Spica (follow curvature of handle even more)
* North Star (never moves in night sky - the Earth's spin axis is pointed directly at it)
* Cassiopeia, the Queen (asterism forms a "W" or an "M" depending on when you view it)
* Orion, The Hunter (Betelgeuse and Rigel - contains a nebula where stars are being born)
* The Pleiades (also known as the Seven Sisters - spectacular with binoculars)
* Aldebaran (bright star in Taurus, the Bull - close to Pleiades)
* Scorpius, the Scorpion (Antares)
* The Summer Triangle (an asterism formed by Deneb, Altair, and Vega)
* Lyra, the Lyre (Vega)
* Cygnus, the Swan (Deneb)
* Altair (forms the asterism (called The Summer Triangle) along with Deneb and Vega)
* The Great Square (an asterism in Pegasus, the Winged Horse)
* Sirius (the Dog Star - brightest star in the sky)
* Procyon (along with Betelgeuse and Sirius forms the Winter Triangle asterism)
* The Teapot (an asterism contained in Sagittarius, the Archer)
* Andromeda, the Chained Lady (contains Andromeda Galaxy)
* Perseus - the Hero (contains a beautiful open double star cluster - use binoculars)
* Leo, the Lion (Regulus, the brightest star in Leo, anchors a prominent asterism, the Sickle also known as the Backwards Question Mark)
* Gemini, the Twins (Castor and Pollux)
* Auriga, the Charioteer (Capella)
PLANETS: (See references to astronomy publications, below. Given here according to distance from Sun)
* MERCURY is closest to the Sun. It is difficult to see because it is never far above the horizon. Many people have never seen it.
* VENUS is extremely bright and has phases just like our moon. Almost everyone has seen it after sundown or before sunrise. It is called the Morning or Evening Star depending on when you see it.
* MARS - the Red Planet - perhaps the most studied planet other than the Earth - may harbor primitive life
* JUPITER - has four large moons that vary in position over days and weeks
* SATURN - noted for its spectacular rings. But in 2009 we see them edge on and they are not so spectacular.
Perhaps the FAVORITE planets for viewing through binoculars or a telescope are Jupiter and Saturn. The Moon can also be very impressive with its craters and lava plains (Mare) pock marked by impacts of ancient asteroids.
Mythology
All visible planets and 48 prominent constellations seen from mid latitudes in the Northern Hemisphere were associated with different stories (myths) used by the ancient Romans and Greeks. (Some of these constellations originated with other ancient cultures). Today the International Astronomical Union has designated each point in the entire sky - visible in the northern and southern hemispheres - as belonging to one of 88 constellations. Most of the names of the prominent stars contained in the original list of 48 constellations have Arabic origins. These Arabic names were established after the Greek document (The Almagest) giving the 48 constellations was published by Ptolemy about 150 AD .
There are many sources giving the mythological stories associated with the constellations. Two excellent ones are given here:
Star Tales developed by Ian Ridpath
and
The History of the Constellations compiled by the University of Oklahoma
If you are interested in general Greek mythology (astronomical and non astronomical), you might want to visit the Theoi Greek Mythology website.
The International Space Station
The International Space Station (ISS) is a very impressive sight. It reflects the sun shortly after sunset or shortly before sunrise. You can obtain information on when to see it by going to the space weather website and giving your zip code (you don't have to be far from cities to see the ISS since it rivels Venus in brightness and can be seen from the center of light polluted cities). The website tells how bright it will be, where and when it will rise (e.g., the SW at 7:35 PM EST), how many minutes it will be visible, the highest above the horizon it will be (e.g., 50 degrees), and where it will set.
Astronomy Periodicals
Many amateur astronomers subscribe to one or more astronomy magazines that have articles on stargazing and other astronomical features. You can find beautifully drawn charts on stars, planets, and moon phases visible during the month of publication. Two of the more popular monthly magazines are Sky and Telescope and Astronomy. These magazines will also send you online weekly reports giving information on all kinds of news and information related to astronomy (just as the actual magazines do).
These periodicals and other sources also give information on the occurrence of meteor showers. Also you are kept up to date on comets and asteroids some of which can be seen with the naked eye, some are binocular objects, and some require higher magnification from a telescope. And details about upcoming solar and lunar eclipses are given.
The telescopes, binoculars and other astronomical items advertised in these publications are generally of good or very good quality. Be careful not to buy items sold at department stores because many or most of them are poor quality and do not live up to their advertising.
Weather and Climate
If it's cloudy, you can't see anything. But sometimes the clouds are thin and the Moon and brighter stars and planets are visible. At other times, it is partially cloudy and if you are patient, you can generally see the celestial objects you want to see. Any time of year can have clear skies but for the Ohio River area, late summer and autumn have the highest probability for clear skies. Another obvious factor is that for winter viewing, you should be clothed warmly. Your body won't be generating heat like it does when you are skiing and if you are cold you probably won't be interested in looking at the stars.
Light Pollution
Light Pollution is a big problem for many amateur astronomers living close to cities. With strong light pollution only the brighter stars can be seen. The farther you are from the center of a city, the less the light pollution there will be and more faint stars will be visible. Much of the light generated in the U.S. and Canada and in other parts of the world is wasted light. The International Dark-Sky Association is trying to reduce such wasted light and preserve areas where light pollution is kept to an absolute minimum. Currently there is a big push in many national, state, and provincial parks to keep the night sky relatively free from light pollution.
The map below shows where light is being emitted into the night sky for northern Mexico, 48 states in the USA, and southern Canada. Cities and even built-up areas along interstate highways can be identified. The black areas show where very faint stars in the night sky can be seen. As one gets closer to cities only the brighter stars can be seen.
The Moon can be a source of light pollution especially when it is close to being full. But crescent moons, especially those that set shortly after sunset or rise shortly before sunrise, have little effect on viewing stars and faint objects in the night sky. And the probability of the moon being out at a given time of night (whatever its phase may be) is about 50 percent.
Your eyes should be adapted to darkness when viewing the night sky. This means you should avoid white light as much as possible. Use a red light since there is minimal negative effect to your night vision. Such light from a headlamp allows both of your hands to be free when moving a telescope or using star charts. Remember that after your eyes are exposed to bright white light, it can take about 20 minutes or more for them to become dark-adapted allowing you to see fainter stars. If you are camping you should turn off or distance yourself from lanterns giving off white light when you do your stargazing.
Care should also be used not to shine headlights from a car at locations where people are observing the night sky.
Counter started on July 31, 2009
