What Is A Star?

A star is a giant, glowing ball of gases held together by gravity. The main gas in a star is hydrogen.

  • Stars come in different sizes, colors, and temperatures. 
  • A star produces great amounts of energy in the form of light and heat. The Sun is a star. 
  • Blue stars are very hot, and red stars are cool. Stars have their own light.

A galaxy is a vast collection of stars. 

Our solar system is part of the Milky Way galaxy.

What Is A Constellation?

A constellation is a group of stars that form a pattern or shape in the sky.

  • Each constellation has a name and has helped people navigate for centuries. 
  • Astronomers use imaginary lines to connect the stars in a constellation, forming a shape that could be an animal, object, or person.
  • There are 88 official constellations. Ancient constellations were discovered without using a telescope.
  • Modern constellations — like the Peacock, Telescope, and Giraffe were identified using telescopes.
  • The Big Dipper and Orion are the easiest to spot.

Changing View Of Stars and Constellations

The view of the stars and constellations changes depending on our location on Earth. 

  • Earth’s Rotation  As Earth spins on its axis, the stars appear to move across our night sky from east to west, similar to how the sun seems to rise in the east and set in the west. 
  • Earth’s Revolution – As the Earth revolves around the sun, the planet’s night side faces different parts of the sky, so the constellations we see change over the seasons.
  • Summer Constellations – Popular summer constellations are Lyra (the lyre), Cygnus (the swan), and Scorpius (the scorpion).
  • Winter Constellations – Popular winter constellations are Orion (the hunter), Taurus (the bull), and Gemini (the twins).

Fun Facts

Here are some interesting facts about stars and constellations:

  • Excluding our Sun, the nearest star, Proxima Centauri, is more than four light years away.
  • The North Star, also known as Polaris, is located very close to the North Celestial Pole, making it appear stationary in the sky.
  • The stars in a constellation are not actually close to each other in space; they appear grouped from our view on Earth. 
  • The brightest star in the sky, as seen from Earth, is Sirius (Dog Star). It is part of the constellation Canis Major.
  • Small patterns of stars within a constellation are called asterisms. The Big Dipper is an asterism.
  • Orion is one of the most visible constellations in the world.
  • The largest constellation by area is Hydra, around 3% of the sky.


Let’s quickly recap what we learned about stars and constellations:

  • What is a star mainly made of? Hydrogen Gas
  • What forms of energy does a star produce? Heat and Light
  • What is a vast collection of stars called?  Galaxy
  • What is a group of stars that form a pattern or shape in the sky? Constellation
  • How did constellations help people for centuries? Used for Navigation
  • What two factors does our view of the stars and constellations depend on? Earth’s Rotation and Revolution 
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