Amateur Astronomy

Amateur astronomers introduce the public to the world of astronomy by holding events in public places.  The best introduction to amateur astronomy is to attend some of these events, and ask lots of questions!

The heavens are filled with wondrous objects that are easily viewed with the help of an experienced astronomer to point the way. Many objects that you can view through a telescope are visible from your backyard with a pair of 7x50 binoculars. You only have to look in the right spot to find them!

The following links are shortcuts to the topics on this page:

Astronomy   Terms   Telescopes      Finders   Telescope Tips    Resources     Dark Skies

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What is Astronomy?

The different types of objects you can see through visual astronomy include:

Don't expect to see:

Other pursuits that astronomers become involved in are:

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Terms you might hear at a star party:

Averted Vision: A useful trick to see very faint objects. Instead of looking directly at the object, look off to one side -- avert your vision. The corner of your eye is more sensitive to faint light than the center.

Star Hopping: A method of finding objects in a telescope by starting at a known location (such as a bright star) and then moving through a small, selected area from one recognizable star or pattern of stars to another until you reach your destination. A telescope can be equipped to find objects in the sky automatically, but some of us enjoy the challenge of finding objects ourselves!

Messier Objects: Charles Messier was a comet hunter in the 1700's who cataloged about 100 objects (galaxies, nebulas, clusters) because he didn't want to confuse them with comets. They are numbered in the order that he found them. There are other more complete numbering schemes, but since Messier recorded most of the best objects to view in a small telescope, we frequently use his designations.

Magnitude: The relative brightness of a star. A star of first magnitude is about 2.5 times brighter than a star of second magnitude. There are only about 20 stars that are first magnitude or brighter.

Meteors: almost always very small in size, with the majority being about the size of a grain of sand. The streak of light you see is this dust speck burning up in our atmosphere. Meteor showers are usually from the dust given off by a comet that passed by the earth's orbit a long time ago.

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Telescopes come in many shapes and sizes, but all are characterized by the amount of light they can gather and focus. The more light they can gather, the fainter the objects that can be resolved and the more detail that can be brought out.

The size of a telescope is measured in the aperture, the diameter of the main lens or mirror that is used to gather the light. The "power" of a telescope is varied by the use of different eyepieces and is not a primary concern as it is limited by seeing conditions. Most objects are best viewed in the 50 - 250 power range, so advertisements of "750 power" are unscrupulous methods of advertising that have little to do with the ability to focus light accurately.


Magnification (power) doesn't mean much. By changing eyepieces, you can get any magnification with any telescope... but you might not want to.

Aperture (diameter) is all-important. Larger-diameter telescopes give brighter images (more light) and sharper images (less diffraction). Smaller telescopes are easier to transport.

Magnification = focal length of telescope ÷ focal length of eyepiece.

Use low power (20 to 40 power) almost all the time. This will generally be your 20- or 25-mm eyepiece. You can't magnify detail that isn't there, so when you make the image bigger, it does not necessarily show any more detail.

With larger amateur telescopes (5 to 8-inch), you can go over 100x.

A frequent question is, "what is the best telescope to get?"  That is kind of like asking, "what is the best kind of automobile to get?"  Like autos, telescopes come in many different models and styles, each with different advantages, different features, and in different price ranges.

Telescopes can be broken down into the following basic categories:


Perhaps the most overlooked type of "telescope". A good pair of binoculars is a cost-effective way of introducing yourself to the night sky. Don't rush to buy a telescope -- learn your way around the sky first.

Many books have been written detailing the different objects that can be viewed in binoculars. The most popular sizes for astronomy are probably 7x50 or 10x50 (the first number refers to the power, the second to the diameter of the lens in millimeters.  The second number is a measure of the ability to gather light) with higher diameters showing more detail at the expense of weight.  Use of the very large binoculars requires a tripod.

Dobsonian reflectors

Also called "Dobs", these are an inexpensive design. They are characterized by a long tube with a mirror at the bottom end and an eyepiece at the top, mounted on a rotating stand. A good starting telescope would be a Dob with a 6 or 8 inch mirror. Dobs are manual in nature, requiring the operator to physically move the scope to point at an object and unless fitted with additional tracking hardware, cannot automatically keep an object in the field of view. Dobs are not suitable for photography. An 8 inch Dob costs around $450-$600.

Newtonian reflectors

Internally, these work the same way a Dob does. However, they are mounted on tripods and so are easier to automate for tracking. The main concern is the stability of the tripod, some low-cost scopes have unstable mounts that make it difficult to view objects. A 4.5 inch reflector makes a good starting scope, and costs $350-$600.


This is a hybrid style, using mirrors and lenses. The most popular type is the Schmidt-Cassegrain (SCT). These scopes look "stubby" because they fold the light three times internally from where it enters the telescope to where it exits at the eyepiece. SCT's commonly have a clock drive, which gives the ability to track objects in the sky. Although they offer no better viewing than a Dob, they are much easier to automate and are suitable for photography. An 8 inch SCT costs $1200 to $3000 depending on the options and tracking hardware.


These look like "typical" telescopes, or what most people expect a telescope to look like. They use lenses to focus the light rather than mirrors used by the Dob, Newtonian, and SCT. Refractors will typically give better views than reflectors at similar, smaller sizes. They are well suited to planetary observing and can be mounted to allow for tracking. An 80 or 90 mm refractor costs $350 to $800, while a 4 inch or larger refractor can cost upwards of $2000.

Telescope Summary

Avoid the so-called "department store" telescopes. Most are technically a refractor, but the quality of the construction is so poor that many people that buy them have a bad experience and abandon the hobby forever. If the advertisement proudly proclaims the power of the scope, beware!

As an economical alternative, get a pair of 8x42, 7x50 or 10x50 binoculars with an introductory book or two. Spend some time learning the sky, then if you or your child is still strongly interested, consider a good-quality telescope such as an 80 or 90 mm refractor or a 4 to 8 inch reflector -- which can sustain a lifelong interest.  

One consideration is that younger children may have trouble comfortably holding binoculars, a tripod may be desirable even with the smaller units.

It should be noted that there are a few good quality scopes of about 3 to 4 inches (larger than 60mm) in size that cost $300 or less, but do your research before you buy.  As the old saying goes, though, "aperture wins", so if you can save up for a 6" mirror, that would allow you to see fainter objects.

One other consideration is how the telescope will be used.  If you'd like to bring your new 'scope to a local club event, or haul it to a distant dark site, make sure it will fit in your vehicle!  Also, consider where you will store your 'scope, and how you will carry it outside.  There is a lot of truth to the old saying that "the best telescope is the one that will be used the most".

Check out the various vendors on the web, starting with those on our favorite links page.  You will also find links to places that post ads for used equipment.  To make sense of the specs that a vendor lists, check out our Telescope Numbers page.

Telescopes generally come with at least one low power eyepiece (for general observing) and some type of finder or sighting system.  A tripod may be included or it may be extra.

A better option may be to get a pair of binoculars and a couple of books to learn the sky, and save up for the scope that best fits your plans.


The simplest telescope mount is an altazimuth:  the telescope can be swung from side to side as well as up and down.  (The name comes from the movement -- both altitude and azimuth.)  This type of mount is simple to use because the telescope is merely pointed in the desired direction.  The primary disadvantage is that the telescope must be moved periodically to keep an object in view as the earth rotates.  A Dobsonian mount is the simplest altazimuth design.  Many small refractors also come on altazimuth mounts.

On the other hand, equatorial mounts have the advantage of being able to track an object as the earth rotates.  For this to work, the polar axis must be pointed to the celestial pole.  As the sky appears to rotate, the telescope will follow the stars by itself, if it has a clock drive, or with the turn of a single knob.  There are two primary types of equatorial mounts in common use:  German and Fork.  There are also equatorial platforms that can be placed under a telescope on a Dob mount, allowing the Dob to keep an object in view for as long as an hour.

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The use of some sort of sighting instrument, or "finder" is required in order to put celestial objects in the main telescope's relatively narrow field of view. There are two basic types of finders: finderscopes, and unity-power "sight" finders.

Finderscopes are small low-power wide-field secondary telescopes mounted alongside the main instrument in adjustable mounting rings for alignment with the main telescope. They usually have an eyepiece with crosshairs for object centering, and a wide field of view which is several times that of the lowest power field on the main telescope. Once the finderscope properly aligned with the main telescope, the user can put an object in the telescope's field by merely moving the main scope around until the object of interest appears centered in the finderscope's crosshairs. It should then be in the field of the main telescope. Some finderscopes have a source for low-level illumination of the crosshairs, which can be useful on a dark sky, as long as the illumination does not wash out the target stars.

Most observers have difficulty seeing much through finderscopes with objectives smaller than 30mm, and for a "standard" finder, a 50mm aperture is recommended.

1x Finders: These are just what the name implies, finders which do not magnify or enhance the view. They range from simple sighting tubes or gunsight-like devices, to illuminated reticle-type systems. The simple tube sights will get you in the ballpark, but in dark skies they can be a little hard to use. The "reflex" sights with illumination put an illuminated dot on a tilted glass plate, allowing the user to look through the plate at the sky, see the dot and place objects on it for finding. However, the object should be visible to the unaided eye for this to work well. Many amateur astronomers have built their own inexpensive dot-reflex finders from simple ones found on some gunsight systems.

One of the best known commercial 1x finders is the Telrad, a reflex type finder which puts a unique three-ring reticle of adjustable brightness in the viewer's field. The rings are 0.5 degrees, 2 degrees, and 4 degrees in diameter on the sky, and are most useful not as a simple bulls-eye, but as a "pattern maker", for star hopping. By using overlays which resemble the Telrad's reticle pattern on star atlases, and centering the target object's chart location in the overlay, star patterns and alignments with the Telrad rings in the area around deep-sky objects can be worked out which can then be duplicated by looking through the Telrad at the night sky. This can make finding even faint non-naked eye objects much easier than with the simple "dot" finders. The Telrad is a bit bulkier than some of the simpler "dot" sights, but it is very popular, especially among Dobsonian telescope users.  Other makers of 1x finders include Televue, Rigel, and Orion.

As for which is better (1x finder vs. finderscopes), it really depends on the individual's preference. Many amateur astronomers use both a finderscope and a Telrad on their instruments for locating objects in the night sky.

Telescope Tips

Eyepieces vary in quality. Those shorter than 8 mm are usually very hard to use (your eye needs to be impossibly close). Most telescopes can be improved by adding high-quality eyepieces. Everybody needs an eyepiece somewhere in the 20- to 32-mm range. A Barlow lens doubles the magnification while preserving comfortable eye distance.

Steady air is necessary for good telescope performance. You will get sharper images if you set up the telescope outdoors at least 30 minutes before you plan to use it, so that temperatures can equalize. Observe over grass if possible; avoid hot asphalt, even after dark. Never observe through a window.

The moon is a rewarding object for any telescope. It is lit from a different angle every day, and you can watch it for a long time without seeing the exact same view twice. Rükl's Atlas is very helpful.

The planets are rewarding once you train your eye. Telescopic views from earth will not look like Hubble photos, but with care, you can learn to distinguish stripes and the Red Spot on Jupiter, the rings of Saturn, etc. Planets are bright and can be observed even in the presence of moonlight and city lights.

Deep-sky objects (star clusters, nebulae, galaxies) require dark country skies and a well-trained eye. Telescopic views are very different from photographs. You can see detail even in the brightest parts of the Orion Nebula, in places that are always washed out on photos. On the other hand, you can't see some objects (such as the Horsehead Nebula) with any telescope — they are so faint as to be "photographic only."

How to find things: You must learn the constellations and learn to use a star map. (If you can't point your finger at the Andromeda Galaxy, you can't point a telescope at it either.) Learning the sky takes practice. Monthly maps in Sky and Telescope and Astronomy Magazines are very helpful.  We recommend Turn Left at Orion (see books in the Resources section).

Constellations are not all equally prominent. The Little Dipper is almost impossible — some of the stars are excessively faint. The Big Dipper and Orion are always easy to recognize. Once you can recognize one constellation, you can use it with a map to find the others. Learn how the stars move by observing the sky regularly over a period of weeks or months, or you'll get lost. For best results, use star maps designed for our latitude (47o N).

To take a picture of the stars at night, try this: Using 200- or 400-speed color slide film, place the camera on a steady tripod, aim it at the starry sky, and expose 20 seconds at f/1.8. This technique also works for photographing bright comets. Color print film is OK if you can get good prints made (most minilabs will print the pictures too light or too dark, tell them the background is supposed to be black, not gray).

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If you think you might be interested in pursuing astronomy as a hobby, you should take advantage of the following sources of information:


Join an astronomy club such as the Battle Point Astronomical Association, P.O. Box 10914, Bainbridge Island, WA 98110. Go to a few "Star Parties" (there is usually two at Battle Point Park each month) where there will be different types of telescopes to look through. Astronomers are friendly and are enthusiastic about their hobby. However, if you are not careful you may end up talking until dawn as they love to discuss astronomy!

Each year there are dozens of amateur gatherings in North America.  Some take the form of star parties at dark sky sites. They are great places to see all kinds of telescopes and celestial wonders.

Other get-togethers are indoor affairs, with programs of guest speakers, exhibits of products, and special seminars. To learn about upcoming events, read the club newsletter, and check out the latest listings in....


Pick up a copy of Astronomy or Sky & Telescope. You can find them at most book stores. They contain the latest news, as well as publish useful monthly sky charts.

When you've joined an Amateur Astronomy Club, you will probably also become a member of the Astronomical League.  Their quarterly magazine is called The Reflector.  

Another magazine is Amateur Astronomy.  Definitely not glossy,  and you won't find it in newstands (except maybe in telescope stores) it contains articles written by amateur astronomers on all facets of the hobby.

Observing Programs

If you're looking for some encouragement and certificates of accomplishment for demonstrating observing skills with a variety of instruments and objects, the Astronomical League also has Observing Clubs. These include the Messier Club; Binocular Messier Club and the Herschel 400 Club, the Deep Sky Binocular Club, the Southern Skies Binocular Club, the Meteor Club, the Double Star Club, and the newly formed Lunar Club.

Each Club offers a certificate based upon acheiving certain observing goals. These are usually in the form of a specific number of objects of a specific group with a given type of instrument. Occasionally there are multiple levels of accomplishment within the club. There is no time limit for completing the required observing, but good record keeping is required.

When you have reached the requisite number of objects, your observing logs are examined by the appropriate authority and you will receive a certificate and pin to proclaim to all that you have reached your goal. Many local astronomical societies even post lists of those who have obtained their certificates.

Books to Get Started

A trip to the local library, a bookstore with a good science section, or a book vendor on the internet will uncover a plethora of reading material!

There are many wonderful books on amateur astronomy, a full list would run many pages. The ones listed here are a few great books to get you started.

You don't need to learn the constellations to enjoy astronomy. However, if you'd like to learn them, get a copy of the classic book The Stars, by H. A. Rey.

For an absolute beginner, a highly recommended place to start is the book Nightwatch by Terence Dickinson.  Easy to read, informative, and includes some selected star charts.

A very good guide to the many different facets of amateur astronomy is The Backyard Astronomer's Guide, by Terence Dickinson and Alan Dyer. This book provides a great overview of our hobby including descriptions of the different types of telescopes, lenses, objects to view, astrophotography, etc. Another recommended book of similar type is Star Ware by Philip Harrington. Either of these books is also useful if you are considering buying binoculars (with a slight edge going to the latter).

When and if you buy that first telescope, you should get Turn Left at Orion, by Guy Consolmagno and Dan Davis. Written for those of us with small amateur telescopes, it contains instructions on how to find the best objects in the sky, and has drawings of what those objects will look like in a 4 inch `scope. Every first telescope should come bundled with this book!

Books to use with binoculars include Exploring the Night Sky with Binoculars, by Patrick Moore, Touring the Universe Through Binoculars, by Philip Harrington, or Binocular Astronomy by Craig Crossen and Wil Tirion.

A few other favorite books are City Astronomy by Robin Scagell (with a focus on urban and suburban astronomy); 365 Starry Nights by Chet Raymo (which contains an interesting story or contellation to view for every night of the year); Star-Hopping for Backyard Astronomers by Alan MacRobert (showing a number of interesting star hops in detail); and the Guide to Amateur Astronomy by Jack Newton and Philip Teece (another good general purpose source, similar to Star Ware and the Backyard Astronomer's Guide mentioned earlier, but with a British flavour).

In our Astronomy Course taught by Paul Middents, the book used is Discovering the Universe by William Kaufmann and Neil Comins.  A wonderful, modern text that comes with a CD-ROM with software and images.

If lunar observing sounds like fun to you, the Atlas of the Moon by Antonin Rukl is highly recommended.  

As you gain experience you may want a detailed sky atlas or a good planetarium software program.

Usenet Newsgroups (on the Internet)

sci.astro.amateur is the one to read. The FAQ (Frequently Asked Questions) files are posted periodically and contain loads of hints and tips and advice.  The list of the locations for all the various FAQ files can be found here.

On the Web

Check out some of the BPAA Favorite Links, as well as the links to Pacific Northwest Astronomy groups on the BPAA local page.  

A few sites (of many) with good information for beginners include: the Prairie Astronomy Club; the Starting Right article from Sky and Telescope; and The Astronomy Connection in California.

Many vendors have basic information on their web sites.  Here's one example from Orion Telescope and Binocular Center. For others, see the vendor lists on our Favorite Links page. 

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Dark Skies

Take a good look at the night sky tonight. Today, many people who live in or near large cities have lost much of their view of the universe. The spectacular view of the night sky that our ancestors had above them on dark nights no longer exists. The great increase in urban population has caused an ensuing rapid increase in sky glow due to outdoor lighting. This excess light has an adverse impact on the environment and threatens to remove our view of the universe.

The increased sky glow is called "light pollution", for it is wasted light that does nothing to increase nighttime safety, utility, or security. It only serves to produce glare, light trespass, and to waste energy and money.

Astronomers are not against night lighting. They have the same needs for quality lighting as anyone else. They advocate the best possible lighting for the task, with lighting designs that allow for all the relevant factors. An important advantage of proper lighting is that it minimizes light pollution while saving energy and improving the utility of the light -- everyone wins.

Here are some solutions to the problem of light pollution:

1. Use night lighting only when necessary. Turn off lights when not needed. Use timers or auto sensors. Use the appropriate amount of light, not overkill.

2. Direct the light downward, where it is needed. The use of well-designed fixtures will achieve excellent lighting control. When possible, retrofit present poor fixtures. The goal is to use fixtures which control the light, placing it where it is needed rather than into the sky where it does no good at all.

3. Use low pressure sodium (LPS) lights where possible. This is the best possible light source to minimize adverse sky glow affects on professional astronomy. LPS lights are the most energy efficient light sources that exist. Areas where LPS is especially good include street lighting, parking lot lighting, security lighting, and any application where color rendering is not critical.

For more information, contact the non-profit International Dark Sky Association, 3545 N. Stewart Ave., Tucson, AZ 85716 or visit their home page.  Also, see BPAA's Lights of Bainbridge Island page.

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