Introduction: Universe | GK Olympiad for Class 6 PDF Download

Universe

• Universe includes living things, planets, stars, galaxies, dust clouds, light, and even time.
• It contains billions of galaxies, each containing millions or billions of stars.
• The space between the stars and galaxies is largely empty.
• Space is also filled with radiation (for example, light and heat), magnetic fields and high energy particles (for example, cosmic rays).
• The age of the universe is 13.82 billion years old.
• The visible universe is at least 93 billion light years away.
• Since the Big Bang, the universe has been expanding outward at very high speed.

Galaxy

• Galaxy is a collection of millions or billions of stars and planets that are held together by gravitational pull.
• There are billions of galaxies in the universe.
• The Sun is one such star among 100 billion stars in our galaxy- The Milky Way or Akash Ganga.
• Earth and all other planets also lie in the Milky Way galaxy.
• Spiral in shape, the Milky Way galaxy, is called so as it looks like a river of milky light flowing from one corner of the sky to another.

Sun

• The Sun, about 5 billion years old, is our nearest star, made-up of extremely hot gases- Hydrogen, Helium and others.
• Temperature of Sun’s surface is 9941°F.
• Sun makes up 99.86% of the mass in the entire solar system and has immense gravitational pull which keeps the planets fixed in their orbit, revolving around it.

Solar System

• The Solar System is made up of the Sun and all of the smaller objects that move around it.
• Apart from the Sun, the largest members of the Solar System are the eight major planets. Nearest to the Sun are four fairly small, rocky planets - Mercury, Venus, Earth and Mars.
• Beyond Mars is the asteroid belt - a region populated by millions of rocky objects.
• These planets are much bigger than Earth, but very lightweight for their size and are mostly made of hydrogen and helium.
  

Planets Facts