Gently singing Twinkle, twinkle, little star may lull a baby to sleep, but beyond the confines of Earth’s atmosphere, the words aren’t exactly accurate. A correct, albeit less soothing, rendition might be: Emit, emit, gigantic ball of gas. 
Stars are huge celestial bodies made mostly of hydrogen and helium that produce light and heat from the churning nuclear forges inside their cores. Aside from our sun, the dots of light we see in the sky are all light-years from Earth. They are the building blocks of galaxies, of which there are billions in the universe. It’s impossible to know how many stars exist, but astronomers estimate that in our Milky Way galaxy Alone , there are about 300 billion.

All that glitters
Some stars shine more brightly than others. Their brightness is a factor of how much energy they put out–known as luminosity and how far away from Earth they are. Color can also vary from star to star because their temperatures are not all the same. Hot stars appear white or blue, whereas cooler stars appear to have orange or red hues.

Looking up
Depending on cloud cover and where you’re standing, you may see countless stars blanketing the sky above you, or none at all. In cities and other densely populated areas, light pollution makes it nearly impossible to stargaze. By contrast, some parts of the world are so dark that looking up reveals the night sky in all its rich celestial glory.

A beautiful cluster 
Ancient cultures looked to the sky for all sorts of reasons. By identifying different configurations of stars—known as constellations—and tracking their movements, they could follow the seasons for farming as well as chart courses across the seas. There are dozens of constellations Many are named for mythical figures, such as Cassiopeia and Orion the Hunter. Others are named for the animals they resemble, such as Ursa Minor (Little Bear) and Canus Major (Big Dog).

Some major constellations are:
* Ursa Major (Great Bear): Ursa Major is a constellation, or group of stars, that appears in the northern night sky. Its name means Great Bear. For thousands of years, various peoples on Earth have thought that these stars formed the shape of a bear.
* Ursa Minor (Little Bear): Ursa Minor constellation, also known as the Little Bear, lies in the northern sky and is the 56th largest constellation in the sky. The Great Bear constellation is represented by its larger neighbor Ursa Major.
* Orion (Hunter): Orion can be seen during the winter late in the evening. It is one of the most magnificent constellations in the sky. It has seven or eight bright stars and is also called the Hunter.
* Leo: Leo contains several bright stars making it one of the most easily recognisable constellations in the night sky. It is visible in both Northern and Southern hemispheres.