Geography
SOLAR SYSTEM
1-Our solar system consists of the sun (the star), planets, satellites, millions of smaller bodies like asteroids, meteorites and comets and huge quantity of dust-grains and gases.
2-Out of the nine planets, Mercury, Venus, Earth and Mars are called as the inner planets as they lie between the sun and the belt of asteroids the other five planets are called the outer planets.
3-The first four planets are called Terrestrial, meaning earth-like as they are made up of rock and metals, and have relatively high densities.
4- The remaining five planets are called Jovian or Gas Giant planets.(Jupiter, Saturn, Uranus, Neptune, and Pluto-dwarf planet)
5-The orbits of the planets are nearly circular, but many comets, asteroids, and Kuiper belt objects follow highly elliptical orbits
6-Nicolaus Copernicus was the first to develop a mathematically predictive heliocentric system (Sun at the center). [Geocentric- Earth at the center]
Solar System and its Components-
1- Sun
2- Eight major planets
3- Dwarf planets (Pluto, Ceres, Eris etc.)
4- Satellites and countless minor planets
5- Asteroids
6- Meteors
7- Comets
8- Debris etc…
* A celestial body moving in an elliptical orbit round a star, the Earth is known as PLANET
* Mercury is similar to the Moon with a surface dominated by craters and a younger area of dark plains presumably made from floods of lava
* Venus is often considered to be the Earth’s twin, but the two planets are not identical.
*A ray of light from the sun takes about eight minutes to reach the earth. Light takes only a second to reach us from the moon.
* Mars has two tiny natural satellites (Deimos and Phobos) thought to be captured asteroids.
* Its(Mars) red colour comes from iron oxide (rust) in its soil.
* Millions of objects, remnants of planetary formation, circle the Sun in a zone lying between Mars and Jupiter. They are known as asteroids.
* Asteroids are small Solar System bodies composed mainly of refractory rocky and metallic minerals, with some ice.
* Asteroids range in size from hundreds of kilometres across to microscopic.