Astronomy is the science that deals with the study of stars, planets and their motions, their positions and compositions. This chapter covers rockets (their parts, propellants and launching), India's space programmes (ISRO, Chandrayaan-1, Mangalyaan, Chandrayaan-2 and Chandrayaan-3) and NASA, including the Apollo missions and the work of Indians at NASA.
1. The Universe – Basic Terms
- Celestial objects: the stars, the planets, the Moon and many other objects in the sky such as asteroids and comets.
- Solar system: the Sun and the celestial bodies which revolve around it.
- Galaxy: a collection of billions of stars held together by mutual attraction. Our Sun belongs to the galaxy called the Milky Way.
- Universe: formed by billions of galaxies. The solar system, the stars and the galaxies are the constituents of the universe.
2. Rockets – History and Uses
- Rockets were invented in China, more than 800 years ago.
- The first rockets were a cardboard tube packed with gunpowder and were called fire arrows.
- In 1232 AD, the Chinese used these fire arrows to defeat the invading Mongol army. The knowledge spread to the Middle East and Europe.
- Rockets help to launch space probes to explore the planets, launch space-based telescopes and put satellites in space.