This book is dedicated to the teacher and my classmates who accompany me on this trip.

• The Universe was the result of a giant explosion called the Big Bang.
• Stars are huge ball of gas where nuclear reaction take place .
• A constellation is a group of stars which make an imaginary shape in the night sky .
• A galaxy is an enormous system of stars dust and gas that is held together by the force of gravity.

The universe includes planets stars solar systems and galaxies.

. Planets and dwarf planets are celestial bodies that orbit around a star and do not emit light

. a comet is made up of ice dust and gases.

.an asteroid is a rocky ,irregular mass that orbits the sun.

.Meteoroids are small pieces of rock or metal from an asteroid or comet that orbits the sun.