PRACTICAL OBSERVING
by John Rummel

(based on a presentation to the Madison Astronomical Society, January 11, 2002)

The emphasis is on "observing." Anyone can "look" through binoculars or a telescope. The art of observing takes practice and training. Fortunately, it is easy to learn how to do, and most motivated novices will quickly learn the difference.

People become interested in amateur astronomy as a hobby all the time. This has not changed over the years. What has changed is the tools that are available for today's amateur. Consider the rise in popularity of inexpensive "goto" telescopes. Do a simple star alignment, enter a planet or deep sky object into the keypad, and the telescope points to the correct object all by itself. Little or no knowledge of the sky is required of the user.

While this may sound wonderful, it conceals a disturbing problem. Without a basic knowledge of, and appreciation for the terrain of the night sky, the amateur astronomer is lacking what many would consider the "soul" of the hobby.

It goes without saying that our culture is losing contact with the night sky. The growing light domes of our urban population centers mean that more and more people grow up never knowing the quiet brilliance of a starry night. Many children have never seen the Milky Way and cannot point out a single constellation. People express surprise at such basic notions that the stars move, or that some stars have names, or that you can often see the moon during the daytime.

With this in mind, let's consider the types of planning and preparation necessary for an observing session. I'm basing most of my comments on my own experience and background, but I think my case is typical of the development of most amateurs.

A fundamental question addressed by all observers is "what's up tonight?" Most veteran observers intuitively know, for example, that if your goal is to observe the Orion nebula, and it's mid July, you've got a problem. The seasonal appearance of the constellations is one of the basic pieces of knowledge newcomers must absorb. This can be done quite easily in a number of ways.

  • Check the current issue of one of either Sky and Telescope or Astronomy magazines.
  • Buy and learn how to use a planisphere. This inexpensive and easy to use tool can quickly tell you what constellations will be well placed for viewing at any time of the year or any time of night.

Planispheres won't help you know where the planets are. Solar system objects change their locations nightly, and from one year to the next, their movement is considerable.

Planisphere
Custom printed star chart

This is an area where the astronomy magazines will be helpful. Each has complete information on how to find the planets, as well as tips on observing more difficult objects such as asteroids and transient objects such as comets.

Another excellent resource is computer programs. The chart to the left was produced by Starry Night Pro, and shows the locations of the planet Saturn and the Asteroid Vesta for the evening of January 11th, 2002. Many such software programs are available, and many are very inexpensive, or even free.

I have several such charts with me anytime I go out to observe.

Computer programs and the magazines are also helpful for determining interesting solar system events to observe. Examples are Jupiter satellite shadow transits or eclipses of those satellites. Such events are simple to observe and very rewarding for the amateur.

Star Charts

Every amateur astronomer should know how to use a star chart. Goto scopes are great, but they are not a substitute for knowing how to navigate around the sky using a map.

Pictured at right is my copy of Tirion's SkyAtlas 2000. Mine is laminated and bound with 2 metal rings. The lamination helps protect it against physical damage and moisture. This particular chart shows stars down to 8th magnitude. It shows the positions of literally thousands of deep sky objects. Galaxies, nebulae, star clusters, double stars, and more.

When using star charts such as this, the best way to begin, and an enjoyable observing experience on its own merits, is to use binoculars.

Tirion's SkyAtlas chart
Binoculars Binoculars?

Many newcomers to the hobby express surprise when they find out how much experienced observers like to use binoculars. Their easy portability and wide fields of view make them ideal for scanning large patches of sky - and this is the best way to learn to use a chart.

Binoculars show images uninverted. This means that what you see in the eyepieces is the same orientation as it appears in the sky. Up is up, left is left, and right is right. This is very useful for orienting yourself to a chart.

Start by studying the chart, Auriga for example, and then scanning the constellation with your naked eye, alternating with the binoculars, until you have a good feel for the major landmarks (bright stars and obvious patterns). Once you have the "lay of the land," start studying the regions around these brighter stars and look for fainter stars and patterns. As you proceed, note the appearance of other objects on the charts. Auriga, for example, contains several open clusters that will be visible in your binoculars. Find them on the chart (they're called by their Messier catalog number, M36, M37, and M38 and then locate them in the sky with your binoculars.

This process is known as "star hopping" and is the bread and butter of learning your way around the sky. Learning to do it with binoculars makes infinitely more sense than with a telescope. The average telescope field of view is less than one degree (a little larger than the size of the full moon). It's much easier to learn your way around a constellation when you can see a larger field of view, such as provided by most binoculars.

Once you find some of those "faint fuzzies," you may be interested in knowing more about them. Another tool in my bag of tricks is this binder. It contains printouts of the Messier catalog (with some info about each object), lists of bright stars, any custom charts I've printed for the evening, as well as the entire NGC catalog (over 7000 deep sky objects). Often when I'm perusing a constellation, I'll notice other objects on the chart near to what I'm currently observing. I'll frequently try to find them too, and then use my binder to look up some info about them.

Binder with charts and objects

So what is the difference between observing and looking?

For the purposes of this article, looking implies a passive exercise whereas observing is active and purposeful.

The looker glances for a moment, and then moves on. The observer studies, considers, examines, and lingers.

A good exercise to illuminate the difference is to watch somebody passively look at an object or scene, and then watch somebody who is trying to sketch or otherwise describe the scene. The act of sketching requires close observation and examination. Amateur astronomers who have made a sketch of the planet Jupiter, or of a section of the lunar surface know the difference.


Some other considerations that deserve mention, though full treatment can be found elsewhere:

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