Robert Sheaffer

Getting Started in Astronomy


Almost everyone finds astronomy a fascinating subject. And many people would like to learn about astronomy and get started making their own observations of interesting celestial objects. But it can be intimidating when one does not know how to begin. As someone who has owned and used telescopes since I was in grade school (a very long time ago!), and has participated in many star parties over the years, let me share what I have learned to help you get off to a good start, without spending a lot of cash. 


My principal advice: start simple and start small. You don’t need a big telescope to start observing. In fact, if you have no previous experience in observing, you may find a large-ish telescope, with an equatorial mount or a Go-To mount, plus its electronics, confusing, heavy, and difficult to use. I have encountered a number of instances where inexperienced observers buy a large-ish and complex telescope, and can’t figure out how to use it. So it stays in its box. But if you buy a small, inexpensive telescope that is easy to use, then after a year or so you can graduate to the larger and more complex scopes, if you feel that you are ready for it. And your small scope will still see plenty of use when you just want to go outside and have a quick look at the moon or something.




To get started in astronomy, you will need three things:


1. Information about what you are going to observe, and when you can observe it.


2. A place to observe, where you get a reasonably good view of the sky, as far from bright lights as is practical.


3. Equipment for observing – a telescope or two, and a pair of binoculars.


Information: People sometimes forget that you will need a good source of information to know what you are looking at, and what it is possible to see. You need to learn the constellations, at least the major ones. Fortunately, that isn’t as hard as it sounds. There are many websites and Apps that provide such information. Start with the brightest stars, which should be easy to identify, and work on learning the star patterns around them. As the night progresses, stars will be slowly setting in the west, while new stars rise up in the east, as the northernmost (or southernmost) constellations spin endlessly around the north (or south) pole (depending on which hemisphere you are in).

Many people are familiar with mobile Apps such as Google Sky, which can help you identify constellations and planets. You just point your phone in a particular direction, and it will (hopefully) tell you what you are seeing. If it works well for you, you have a very useful tool. However, sometimes phones have difficulty finding magnetic north because of local magnetic disturbances, or configuration issues in the phone, and it is possible that what the program shows you might not match up with what you see. Also, not all phones have the capability to read the phone’s angle of elevation (“accelerometer”), or magnetic orientation. If that seems to be the case, don’t fret – just try a different approach.


There are many large and sophisticated astronomy software packages, some of them rather expensive. You might someday want to buy one of them, but again my advice is to start and start simple. Don’t spend money on astronomy software until you have gotten all you can from free (or almost free) sources. One of the very best sources of free astronomy information is the website , and its associated Android App. It gives you simple and accurate sky maps, positions of the moon and planets, information about eclipses, satellite passes, and even comets and asteroids. This source alone gives you most of the information that the beginning observer really needs. If you have the Heavens Above Android App, it gives you a terrific list of “nightly events”: the time of sunrise and sunset, moon risemoon set and , twilight beginning and ending, satellite passes, etc. For satellite passes, the App will show you the satellite’s real-time position, continuously updated for your location, against the background of stars. You can sit down in a lawn chair, and use this App to track bright satellite passes across the sky. That is a great way to learn the constellations.small,

Observing Location: Many people (myself included) often observe from their back yards. This may not be the very best location, but it is close by, and convenient! Even if you cannot see the faintest objects from your back yard, probably you can still see a lot. However, if you live in an apartment in the city, this may not be possible for you, so you need to find some other location. Most big cities have an astronomy club which organizes public star parties, as well as private events for their members. If such a club exists in your area, you will probably want to join it. 

Not only does the club give you a place to observe, but you can meet other observers and learn a lot from them. To observe in really dark skies, many people go on camping trips with their telescopes and binoculars. Up in the mountains, or in the desert, you can get far away from city lights. When the Milky Way is easily visible, you know that you have a clear, dark sky that will allow you to see many faint objects. (And if the Zodiacal Light is conspicuously visible along the zodiac, you know that you are experiencing some of the most perfect, absolutely dark skies available anywhere. I once saw the Zodiacal Light shining amazingly brightly in the pre-dawn skies of the Grand Canyon National Park, and another time at the edge of the Colorado Desert in California, near the Salton Sea.)

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What telescope to buy?  There are seemingly endless choices. After years of observing, I have concluded that the best small telescope for the beginner is a short focal length reflecting telescope on a Dobsonian (alt-azimuth) mount. These are inexpensive, relatively easy to use, and give excellent wide-angle views of star clusters and other deep-sky objects. I don’t recommend anyone buying those small, relatively long focal length refracting telescopes (f/10 or f/15) that are commonly sold in department stores. These are difficult to use, and do not give wide-angle views. Also they typically have poor color correction, so when you look at Jupiter it is likely to be tinged with red or blue. 




Some recommendations:


Celestron First Scope 76mm reflector. There are several different models that are largely the same. Under $60 on-line.






















Orion Sky Scanner 100mm reflector, about $110 on-line.


Meade Light Bridge 114mm reflector, about $150 on-line.

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You can also find similar small Dobsonian reflector telescopes in 125mm or 150mm sizes, for about $200 or $300. I don’t think the beginner ought to buy anything bigger than this for one’s first telescope. These are table top telescopes, meaning that you typically place them on a picnic table or whatever flat surface is available. Some of these scopes (probably only the 100mm or smaller) can be attached to a camera tripod. You can also use them on a small, sturdy folding table.


You will also probably want to buy at least two wide angle eyepieces, with at least a 60 degree apparent field. Your telescope will come with one or two eyepieces, but frankly they will not be very good. You can improve your views immensely by using a better eyepiece. The Meade Series 5000 HD-60° eyepieces (about $80 on-line) and the Celestron X-Cel LX eyepieces (about $70 on-line) are excellent choices. Choose a focal length that is the same as, or approximately the same as, the eyepieces that came with your telescope. You can spend a lot more money buying eyepieces, but for small scopes like these it won’t help you much. Premium eyepieces can easily cost $300, $500, or more, and these will give excellent views on larger scopes. However, they were not designed to be used in such small scopes. For those occasions when you want to observe using a higher power, for example when looking at planets, you can buy a Barlow lens for under $100 that will double the power of any eyepiece. So a 10mm eyepiece becomes effectively a 5mm eyepiece when the Barlow lens is used. (These small reflectors are not designed for high-power viewing of planets and such, but they will typically give good images up to about 100x. Theoretically a 4” telescope can perform well at 200x or more, but these small, inexpensive scopes probably will disappoint if you try for such high magnification.)

The eyepieces you buy can be used in any scope using a 1.25” diameter eyepiece, which is the standard for small scopes. You can even use them in big telescopes that take 2” diameter eyepieces, although typically you’ll get better results with the larger (and more expensive) 2” eyepieces. But it is not unusual for a short focal length 1.25” eyepiece, say 6mm, to be used in larger scopes for high power viewing.


How can you find an object that you can’t see without the telescope – say, a globular cluster? Here is a trick that works well on small scopes using an alt-azimuth mount. Assuming that your smart phone has the “accelerometer” feature (capable of reading the angle of elevation of the phone, once calibrated), you can use a “level” App (I use the Android App “Spirit Level”) to read the scope’s altitude. Fix the phone to your scope, using Velcro. Real-time software such as RTGUI will tell you the elevation of the object you seek. Raise the scope until the App reads the same elevation as the object you seek, then turn the scope in azimuth to the approximate location. Then just scan slowly in azimuth until the object you seek comes into view.


Another little trick you might want to use is: get yourself a 5mw green laser (under $10 on-line). Use Velcro to fix it to your telescope, like a rifle scope. If you line it up carefully, the beam will point to the same spot as your telescope. So when you want to find something, you don’t need to get your head down and sight along the barrel of your scope. You just move the scope until the beam is pointing at what you want to see. (You’ll need to be a little careful not to zap any airplanes with your laser. These lasers should only be used by adults.) You can also use the green laser to point to objects and help others learn the stars and constellations.

credit Bob King from Universe Today

Some people may find it hard to believe the ‘small is beautiful’ gospel I am preaching. Let me relate to you an incident. One night I was camping out at a big star party under a fairly dark sky. There were dozens of telescopes present, of all sizes. One guy had a huge 24” scope, and was showing people globular clusters in the Triangulum galaxy. (They are very, very faint!) Everyone was walking around, sharing views in each others’ scopes. I had my 11” Go To scope set up, as well as my little 76mm Celestron First Scope. It was about 1 AM when a friend of mine wandered by, one of the most experienced observers in the club, who owns a private observatory. I had the First Scope pointing at the Andromeda galaxy, using a wide angle eyepiece at only about 35 power. The field of view was about 2 degrees, so you could see the whole galaxy in its full extent. Both of its satellite galaxies were easily seen. My friend looked through the First Scope, and started laughing. I asked, what was so funny? He replied, “I have been walking around here all evening, looking in all these big scopes. And this is the best view I have seen all night!” In a fifty dollar telescope with a fifty dollar eyepiece.

After you have mastered your small telescope and are longing for something bigger, you can go in several directions. Many people will want to get a Cassegranian reflecting scope of 8” or 10” size, on a Go To mount. This will allow you to find objects with the touch of a button, and will set you back about $1500 or more. (You probably don’t want to buy a telescope on an equatorial mount, unless you are serious about doing a lot of astrophotography.) You can buy an 8” Dobsonian telescope (with no electronics) for about $500. If observing planets and double stars is your main interest (a good choice if you observe near a big city), you might want to buy an Apochromatic short focal length refractor, which gives very sharp, fully color-corrected images even at high powers, and typically costs $1500 or more. 


I hope that this information has been helpful to you, distilling what I have learned through experience over the years. And I hope it encourages you to take the plunge, to buy yourself a small telescope, and learn how to use it.

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