So, you want to begin exploring the nighttime sky, eh? Anyone can look at the stars, but to be able to search for and identify astronomical objects that have been known and cataloged for hundreds of years is another thing. To get the most out of your observing time, there are some things that every amateur astronomer needs to know.
There are a couple important terms that every beginning astronomer must know. Magnitude is a measurement of a star’s apparent brightness. The higher the magnitude number, the fainter the star appears. Magnitudes have also been applied to planets, nebulas, galaxies, etc. For example Polaris, the North Star, is a magnitude 2.02. Venus can shine as bright as magnitude –4.4 and the Sun weighs in at a blinding magnitude –26. Another important term is seeing. Seeing is a description of the clarity of the current view of space. The things that cause poor seeing are humidity, weather fronts, light pollution, air pollution, and atmospheric turbulence. For these reasons, professional astronomers like to place observatories in areas such as the middle of the desert or up on a mountain, where they can find the calmest atmosphere and few or no lights to pollute the night. The world’s biggest telescope is found at the Keck Observatory in Hawaii, which is at an altitude of 13,796 feet on the summit of the Mauna Kea volcano.
There is an easy technique to determine the approximate location of astronomical objects in relation to each other. First, extend your arm horizontally and make a fist. When looking over the top of your fist at the night sky, any object over the top of your fist can be said to be 10° above the horizon. Therefore, one fist is equal to 10°. By stacking one fist on top of the other until you are looking straight up, or at 90°, you will realize it took 9 fist widths to get to the zenith (or straight up) thereby confirming that one fist width equals 10°. This in turn means that one finger width equals 2.5°. Now, if I told you that Venus is a magnitude –4 and 17.5° south of the moon, you should be able to locate it easily.
To ensure decent seeing, it is recommended to wait at least one hour, if not longer, after full dark before beginning to observe. This allows time for the atmosphere to settle down and for any remaining sunlight to be sufficiently hidden behind the Earth. Observing in a remote or rural area will offer significantly better Seeing as compared to a urban setting, due to the amount of light pollution. Also, winter is the best season for good seeing since the ambient humidity is at its lowest.
To make you’re observing experience as enjoyable as possible, here are a few last thoughts. Finding your way around in the dark can be a real problem, so a flashlight is a good thing to carry, but not a normal flashlight as this will cause stress on your eyes. There are several places that sell flashlights with red bulbs or red filters for this very purpose. The red light won’t cause your pupils to contract, therefore allowing you to maintain your (night) vision. Remember that it can take your eyes up to 30 minutes to fully dilate once outside. Any objects with a magnitude lower than 6 cannot be seen without binoculars or a telescope. I challenge you, new amateur astronomer, to observe the Galilean Satellites of Jupiter, which are easily viewed with any set of binoculars.
By utilizing these tips, you can begin to effectively explore the nighttime sky. Once you get a good feeling of how to navigate the stars, you may then want to invest in a good telescope which will allow you to view deep sky objects such as nebulas. Happy Observing!
