“Will my constellation map show the Orion constellation? Or the Scorpio constellation? Or Cassiopeia?”
Well, it depends. Your constellation map will show between 7,000 and 8,000 stars, depending on the place, date and time you choose to represent. It would be really hard to count them, so at the bottom right corner of your constellation map, the exact number of stars is indicated.
When you create your custom sky map, you can choose to toggle on/off the constellations names and lines as well as the star names. If you turn off that option, your celestial map will show no constellations at all, only the stars and planets visible at that moment in time, over that place. Leave the option on, and you will see the constellations names and lines on your celestial map.
How many constellations are visible in the night sky?
There are 88 constellations in the sky, as defined by the International Astronomical Union (IAU). How many you see and which ones depends very much on the location from which we observe the sky, the time and the season.
Because our planet travels through space orbiting around the Sun, our view of the stars changes throughout the year. At the same time, the Earth spins on its axis, the stars we see in the sky appear to move from east to west, and so do the constellation they form.
Out of the 88 constellations, 36 are mostly found in the northern sky, while 52 can be seen in the southern sky. We can never see all 88 constellations at the same time, from any point on Earth.
Northern hemisphere constellations appearing on a constellation map
Most modern northern constellations are based on the Ancient Greek constellations. Their names reminds us of the Greek myths they are associated with. So if you are based in North America, Europe, or anywhere north of the equator, you will generally see on your constellation map:
- The 10 constellations in the Ursa Major family (Great Bear or Big Dipper), including the Ursa Minor (Little Bear or Little Dipper), Lynx, Comes Venatici (the Hunting Dogs), etc.
- Most constellations in the Perseus family: Andromeda (the Chained Maiden), Auriga (the Charioteer), Cassiopeia (the Queen), Cepheus (the King), Pegasus (the Winged Horse), Perseus itself, etc.
This example of a constellation map shows the sky over California, more precisely San Francisco, in late afternoon at the spring equinox. The Sun was visible at that time of day. Though the stars were not actually visible due to daylight, the map shows their precise location, as well as most of the northern hemisphere constellations.
Ursa Minor, the Little Dipper, is the easiest constellation to find on Greaterskies northern hemisphere constellation maps, because it includes Polaris, the Northern Star, always shown at the center of the grid. Polaris, so useful to sailors because it indicates the north, is not visible from the southern hemisphere.
Ursa Major, Pegasus, Draco, and Pisces are among the largest northern constellations, while Canis Minor is one of the smallest.
Southern hemisphere constellations appearing on a constellation map
Observing the sky from a location south of the equator, we can see a very different picture, with different and more numerous constellations. Some southern hemisphere constellations can sometimes be observed from Northern latitudes, like Scorpio in summer, close to the horizon. But the most famous of the southern constellations, the Southern Cross (Crux), is absent from the northern latitude sky.
This sky map shows the stars and constellations over Melbourne, Australia, at the fall equinox, on March 20, 2015.
While the North Star is not visible from here, the two brightest stars in this night sky are Canopus and Sirius (in the Canis Major constellation).
Perseus, which we can see at the centre of the celestial vault on the previous map, shows just above the horizon on this one. Orion, the Hunter, marked by nearly a dozen bright stars, including Rigel and Betelgeuse, is very visible.
How many constellations and stars will my constellation map show?
Your custom sky map will show three to five dozens constellations. If you pick a location in the Southern Hemisphere, there will be a higher number. Good reason to get married in the South Pacific, isn’t it?
In addition to the location, the exact constellations you’ll see and their place in the celestial sky also depends on the time of day or night you choose. Greaterskies star maps allow to chose the exact time, because the stars move across the celestial vault (or more exactly, the Earth spins on its axis) during the course of a 24h day.
To see know exactly which constellations will show in your own special sky, create your own constellation map.
You can also download for free a full size poster showing the map of stars and constellations over Stephen Hawking’s birth place. Please visit our tribute to Stephen Hawking.