2009 marks the beginning of the International Year of Astronomy. It is probably no surprise then, that this particular "Year of Astronomy" occurs 400 years after Galileo Galilae first turned the telescope skyward. The anniversary of such a world changing event is bound to have many people asking "how do I become an amateur astronomer like Galileo?" The answer is as simple as going outside and looking up. However, a few general tips will help make exploration of the sky easier and more enjoyable.
The first thing that usually puts many amateurs off when they go outside on a clear evening is how many stars are visible. For observers under dark skies, the number of stars seems almost overwhelming. Fortunately our ancient ancestors devised a means for us to make sense of the jumble. They created patterns out of the brightest stars. These patterns are called constellations. However, the names and characters of the constellations was different from one culture to the next. Therefore in the 1920's the International Astronomical Union assigned fixed names and arbitrary boundaries for the constellations. Today there are a total of 88 constellations in the sky and every star and deep sky object resides within the boundaries of a constellation. The best thing new amateurs can do is to familiarize themselves with the constellations visible from their latitude during which seasons.
To facilitate learning the names of constellations and when they are visible an amateur astronomer can use one of two simple tools. The first is a field guide to the night sky. There are several versions from various publishers but a book, no matter how small has the disadvantage of not being very portable. A more manageable tool is a planesphere. This tool, based on the Astrolabe designed by Arab travelers of the deserts of North Africa, shows the positions of the stars for any date and time the observer wishes to use. For example, if an observer wishes to observe the night sky on December 31st at 10:00 pm, she simple aligns the date and times on the edge of the planesphere and the wheel inside shows the positions of the stars. The year does not matter because the positions of the stars change very little over the course of a human lifetime.
Once the observer is familiar with the constellations, she may discover a bright object among the stars that does not appear on his star chart. After careful observation over a series of nights she discovers that the object has moved relative to the stars. At this point the observer may need to turn to her pocket astronomy guide to discover that the slow moving light is really a planet. From there she may attempt to locate other planets in the sky, or learn the characteristics of the planet she has just discovered. Now the new amateur has started a marvelous journey into a realm that few really understand. But where can this intrepid traveler learn more?
Most cities or moderate size have either a local astronomy club, a planetarium or both. An astronomy club is a collection of like minded individuals who love the night sky. Many of them own telescopes and most of them are more than willing to share their knowledge and expertise. Planetariums are indoor theaters that project simulations of the night sky onto a hemispherical dome above the audience. Any planetarium worth it's salt should be willing (or at least able) to give a short tour or "star walk" of the night sky for the night you are visiting. If the community in question is too small for either of these resources, most have at least a small public library.
We may never know if Galileo had any idea of the revolution he would spark when he first turned a telescope skyward. Yet it is probable that without his contribution (some would use the term fathering) to the science, it would not enjoy the wide spread appeal that it has today.