Have you ever laid on the grass looking up at the clouds and tried to recognise shapes in them?
Constellations are simply recognisable shapes in the stars, and by convention there is a standard mapping of the whole sky.
Stars in a constellation are not related to each other by distance, size, brightness or origin. They just look close together from our perspective, as though they were painted on the inside of a sphere. In reality they could be many thousands of light years distant from each other, but right next to each other in the sky.
That doesn’t mean that you can’t make up your own. So you can “discover” all kinds of constellations, but nobody else will recognise them.
Most cultures recognise constellations that are different from the standard. They are usually based on animal shapes, landscape features or mythology. Learning how other cultures perceive the sky is also a rewarding part of amateur astronomy.
Most of the world’s population are familiar with are the 88 “Modern constellations” though many were named thousands of years ago.
The most well known constellations are the Zodiac Constellations. There are 13 of these. They have familiar names like Sagittarius, Scorpius, Virgo. Most of them were named by the Ancient Greeks.
These constellations appear on the Ecliptic, or near the path of the Sun through the sky. Ophiucus was recently added to the Zodiacal constellations because movement in the relationship of the Earth to the Celestial sphere meant that this constellation is now on the ecliptic.
Image: User:Tauʻolunga - Wikipedia
The whole sky is covered by the constellations. There are 88 if them in total.
Constellations are one way we find objects in the sky. Each constellation has a fixed boundary, and borders on other constellations. Stars are named for the constellation they are in, and their rank of brightness, from alpha as the brightest through the Greek alphabet.
There are exceptions to the naming rule. For example Alpha Piscis is not the brightest star in Pisces.
Finding constellations and remembering their positions, appearance and when they appear in the Sky is a basic skill of amateur astronomy. Constellations are actually quite difficult to identify from a dark site. When you are looking toward the main part of the Milky Way, there are so many stars, all looking bright and magnificent, that the shapes of constellations can be obscured obscured.
Also, many constellations are made up of fairly dim stars so finding them in a brightly light-polluted sky can be a challenge.
Learn to Recognise Constellations
Here are some tips for identifying constellations.
The best place to start is with a good star map. There are plenty of these available in apps, online or in astronomy publications. Sky Map Online is an example. Follow these steps to identify a few constellations. Learn to recognise them and their brightest stars before learning some new ones.
This is an example of a star map of Pisces:
- Review a star map to know what is visible from your location at this time of year.
- Make a note of the constellations you are looking for. On the star map familiarise yourself with its shape, where it will be in the sky, and what its brightest stars are.
- Take a note of the bright stars in adjacent constellations. this will help you locate your constellatons.
- Go outside and look toward the area you think the constellations are located.
- Locate the brightest stars. The brightest is usually alpha, and often has a name, such as Sirius, which is Alpha Canis Major. Using a good star map you’ll be able to pinpoint its location in the sky.
- Make sure you have the star map properly oriented. Starmaps print with east and west reversed so that you can hold them up to the sky.
- Do your best to locate the main outline of the constellation. Remember that some are large and take up a lot of the sky, others are much smaller. In the star map above you’ll see that Pisces takes up a larger space in the sky than Triangulum does.
- If you can’t find it, you have most likely incorrectly identified the brightest star, and picked one from a neighbouring constellation instead.
- Try to remember how the constellation looks in the sky, where it is in the sky, and how you found it.
- Go out tomorrow night and find your constellations again. Keep doing this until you can identify it without a star map. Remember that it will move slightly each night, and after a few months It wont be visible in your sky any more.
Try a few adjacent constellations each night. Over a year all the constellations you can see from your latitude will become visible. It will probably take longer than this to learn all the constellations, but it is worth the effort.
Unless you live at the equator you’ll need to travel to see all the constellations.
In this video I talk about identifying Pisces, with the intent of locating Uranus, but the principles are the same.
Good luck. Learning constellations is not always easy, but when you can identify the sky above you will be able to discover all the beautiful things that it contains.
Originally published in Quora. (Edited)