This book is made with the aim of informing you a little more about the universe...

    Outer space is vast and fascinating. It is full of stars, planets, galaxies and other celestial objects. Our planet, Earth, is only a small part of this vast universe. Exploring the universe is an exciting field. Astronomers use telescopes and  other tools to study the universe. They have discovered exoplanets, planets orbiting stars other than the sun, and have learned more about the composition and age of the universe. The universe it is immense and constantly expanding. The universe is believed to have begun with a huge explosion called the Big  Bang approximately 13.8 billion years ago. 

What are the stars?

   Stars are bodies that have their  own light and emit heat. They are giant spheres (balls) of gases that glow in the dark. The sun is a star.

What are the planets?

   Planets are rocky or gaseous bodies with a spherical  shape and no light of their own. They revolve around the stars and receive light and heat from them. The path they travel around the star is called its orbit.

What are natural satellites?

     A natural satellite is a celestial body that orbits a planets. Generally the satellite is smaller and accompanies the planet in its orbit around its parent star. Unlike the fragments that orbit forming a ring, it is the only body in its orbit. The term natural satellite is contrasted with that  of artificial satellite, the latter being an object that revolves around the Earth, the Moon or  some planets and that has been manufactured by humans.

     A galaxy is a collection of stars, gas clouds, planets, cosmic dust, dark matter and energy gravitationally bound together in a more or less defined structure. Some are destined to collide, like the Milky War and Andromeda.

What are galaxies ?

-Comets are objects with a lot of water in their composition. They have quite elliptical orbit and when they approach the sun, the ice is heated and turns into a gaseous state directly because it does not have atmospheric pressure.

 -An asteroid is a relatively small rocky body (smaller than a dwarf planet) usually of quite irregular shape.

 -A meteorite is a rocky body of relatively small size that has passed through the atmosphere and reaches the ground without completely disintegrating. 

What are comets, asteroids and meteorites?