Our universe is very vast.
Our universe is very vast. It consists of the Sun, billions of stars, the moon, the planets and other heavenly bodies.
THE SUN AND THE STARS:
A star is a huge ball of hot gases. It produces light on its own. The sun is also a star. It provides heat and light to the earth. The light coming from the other stars seems to be very dim because they are far away from the earth. We cannot see them during the daytime because of the bright sunlight. Sometimes, we see groups of stars forming particular patterns. They are called constellations.
The sun and the nine planets belong to a family called the solar system. The nine planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto.
These planets revolve around the Sun in a fixed path called orbit. Each planet has its own orbit. They do not have their own light but reflect the light of the sun falling on them. Each planet takes a definite time to complete one revolution around the sun. a planet also rotates or spins like a top around its own axis.
Among the nine planets, Mercury is the closest to the sun. Venus is the brightest planet whereas Jupiter is the largest planet. Saturn is the planet with rings while Pluto is the farthest planet and, therefore, coldest also. The earth is the only planet where life exists.
Satellites are the heavenly bodies that revolve around the planets. The moon is the natural satellite of the earth. It does not have a light of its own. Other planets also have ‘moons’ or natural satellites. Mercury and Venus have no moons at all.
Asteroids are the small rocky bodies between the orbits of Mars and Jupiter. They revolve around the Sun. there are approximately 40,000 asteroids between Mars and Jupiter.
Meteoroids are small heavenly bodies formed as a result of collisions between asteroids. They are made up of small bits of rocks or metals. Many meteoroids fall down to the earth. When these meteoroids reach the earth’s atmosphere, they get heated by the friction with air and get burnt to form bright shooting stars. These are called meteors. Most of them are stony bodies that tend to break up into fragments and reach the earth’s surface. They are now called meteorites.
Comets are heavenly bodies which are made up of rocks and gases. They revolve around the sun in long, parabolic orbits. Comets seem to appear suddenly in the night sky because the brighten only when they come close to the sun. As they approach the sun, the gases evaporate to form long, luminious tails and distinct bright heads.
A cluster of stars is called galaxy. A galaxy contains billions and billions of stars. The Milky way is the galaxy to which sun and its nine planets belong.