Getting to grips with what’s in the night sky
One of the most confusing things novice amateur astronomers have to deal with is trying to make sense of the about 3 000 stars that are visible with unaided vision. It’s gets worse; a pair of binoculars will let you see about 200,000 stars, while upgrading to a 3-inch telescope will let you see about 5 million or so, and that is not even under totally dark skies.
As a novice you probably have no clue how to start looking for something among the multitude of stars, but there is an easy way to make sense of it all- just learn the constellations, and especially the constellations that never sets for observers in the northern hemisphere. These are called circumpolar constellations, and there are several of them visible from the UK, such as Ursa Major, Ursa Minor, Draco, Cepheus, Cassiopeia and Camelopardalis. Here is how it will help you…
All celestial objects have “addresses”
Except for the Sun, all celestial objects can be found by looking for them within a constellation. For instance, if an object’s coordinates places it in say, Ursa Major, all you need to do is look for Ursa Major, which narrows down the field of search considerably. Once you have found the right constellation, you can easily find the specific object you are looking for.
However, finding the constellation might not be as easy as it sounds, since some stars that make up a constellation are sometimes too faint to be seen with unaided vision. Fortunately though, many constellations contain well known asterisms, which are groups of bright stars that trace out a figure in the sky. In the case of Ursa Major, the Plough (Big Dipper) is very prominent, and easy to find. The image below illustrates this very clearly.
In this particular image (that consists of a photograph and a line drawing from a star chart), it is clear that the other stars that make up Ursa Major are not clearly visible in the photograph; however, a star chart (Fig.2) will show all the stars and other objects within any given constellation. Note the series of black dots at the bottom of the star chart; in a chart of this type the size of the dot is related to the magnitude of the star as seen from earth. Therefore, the bigger the dot is, the brighter the star is.
Learn the sky one constellation at a time
With a bit of practice, the entire Ursa Major constellation will jump out at you as soon as you look the Plough, since the human brain is very good at making, and remembering patterns. Nonetheless, recognizing the constellation is not enough. While the stars that make up the constellation cannot be resolved into discs, they can serve as markers from which to “star hop” to galaxies, star clusters, nebulae, and other objects within the constellation that are visible to amateur equipment.
However, note that the figure of a bear is only a small part of the constellation. The entire white area in the Map of Ursa Major comprises the constellation proper, so do not confine yourself with just the stars that make up the Bear. The same is true for all the constellations, so take your time to learn the 68 constellations visible from the UK one by one, starting with the 5 that never set.
Buy an atlas of the stars
Star atlases and charts come in many flavours, but getting one, and learning how to use it to identify constellations by their principal stars is an absolute requirement if you want to learn to enjoy exploring the heavens. However, star charts are not for everyone, because some charts can be more confusing than the sky itself, especially if you do not have general sense of how the sky is arranged, and how this arrangement changes throughout the year.
A simpler approach that works well for many beginners is to use one of the many free planetarium programs available online to print out a chart for a specific day. Most, if not all such programs have the ability to present the sky from any point on the planet, which makes it easier to relate the chart to the sky as it appears from the observers’ point of view.
Moreover, planetarium software can also be set to show only the brightest stars in any given constellation, or to only show a particular constellation and its boundaries, which makes learning the constellations a whole lot easier.
One more thing
Do not attempt to see an entire constellation with a telescope. Telescopes reduce the visible field, effectively rendering most of a constellation invisible, so first identify the constellation without optical aid before trying to locate an object within the constellation. If you ar eunsure of what equipment to use, then there are many guides online that detail a list of recommended stargazing products for beginners.