Star Charts and Their Many Uses

The night sky is a fascinating place to explore. Most backyard skygazers begin by stepping out each night and marveling at whatever appears overhead. In time, however, nearly everybody gets the urge to know about what theyre seeing.  Thats where sky charts come in handy.l Theyre like navigational charts, but for exploring the sky. They help observers identify stars and planets in their local skies. A  star chart  or a  stargazing app is one of the most important tools a skygazer can use.  They form the backbone of specialized astronomy apps, desktop programs, and are found in many astronomy books.   Charting the  Sky To get started with star charts, search out a location on  this handy Your sky page. It  lets observers select their location and get a real-time sky chart. The page can create charts for areas around the world, so its also useful for people planning trips who need to know what the skies will contain at their destination. For example, lets say someone lives in or near Fort Lauderdale, Florida. They would scroll down to Fort Lauderdale on the list​ and click on it. It will automatically calculate the sky using the latitude and longitude of Fort Lauderdale as well as its time zone. Then, a sky chart will appear. If the background color is blue, it means the chart is showing the daytime sky.  If its a dark background, then the chart shows the night sky.   The beauty of these charts is that a user can click on any object or area in the chart to get a telescope view, a magnified view of that region. It should show any objects that are in that part of the sky. Labels such as NGC XXXX (where XXXX is a number) or Mx where x is also a number indicate deep-sky objects. Theyre probably galaxies or nebulae or star clusters. M numbers are part of Charles Messiers listing of faint fuzzy objects in the sky, and are worth checking out with a telescope. NGC objects are often galaxies. They may be accessible through a telescope, although many are fairly faint and hard to spot. Astronomers over the ages have collaborated on and created different lists of sky objects. The NGC and Messier lists are the best examples and are the most accessible to casual stargazers as well as advanced amateurs. Unless a stargazer is well-equipped to search out faint, dim, and distant objects, the advanced lists really arent of too much importance to backyard-type skygazers. Its best to stick with the really obvious bright objects for good stargazing results.Some of the better stargazing apps also allow a user to connect to a computerized telescope. The user inputs a target and the charting software directs the telescope to focus on the object. Some users then go on to photograph the object (if theyre so equipped), or simply gaze at it through the eyepiece. There is no limit to what a star chart can help an observer do.   The Ever-Changing Sky Its important to remember that the sky does change night after night. Its a slow change, but eventually, dedicated observers will notice that whats overhead in January is not visible in May or June. Constellations and stars that are high in the sky in the summertime are gone by mid-winter.  This happens throughout the year. Also, the sky seen from the northern hemisphere is not necessarily the same as what is seen from the southern hemisphere. There is some overlap, of course, but in general, stars and constellations visible from the northern parts of the planet arent always going to be seen in the south, and vice-versa.The planets slowly move across the sky as they trace their orbits around the Sun. The more distant planets, such as Jupiter and Saturn, stay around the same spot in the sky for a long time. The closer planets such as Venus, Mercury, and Mars, appear to move more quickly.   Star Charts and Learning the Sky A good star chart shows not only the brightest stars visible at a given location and time but also gives constellation names and will often contain some easy-to-find deep-sky objects. These are usually such things as the Orion Nebula, the Pleiades star cluster, the Milky Way galaxy that we see from inside, star clusters, and the nearby Andromeda Galaxy. Learning to read a chart enables skygazers to know exactly what theyre looking at, and leads them to explore for more celestial goodies.  Ã‚   Edited and updated by Carolyn Collins Petersen.