​the earth is the only planet where life exists

​it is the third planet from the centre of solar system. it is spherical in shape. it orbits around the sun

​the moon is the only natural satellite of the earth. it revolves around the earth. it is the only heavenlybody where humans have ever stepped

​the earth and the moon orbit around the sun, which is a star. the sun provides us light and heat during the day. its the earth's movement around the sun once a year leads to change in seosons

​an asteroid is a chunk of rock and metal in outer space. a satellite orbits a planet. a comet is basically a big ball of ice and and rock. a dwarf is similar to planets but is smaller in mass

​mercury, venus, earth and mars are closest to the sun thus they are called inner or terrestrial planet because of their solid rocky surfaces. jupiter, saturn, uranus and neptune are called outer or jovian planets

​the inner and outer planets are separated by the asteroid belt, this is a region between orbit of mars and Jupiter, where most of the asteroids in our solar system are found orbiting the sun.

​earlier there were nine planets in the solar system but in august 2006 due to its small mass it was reclassified as 'dwarf planet' by international astronomical union now there are 5 dwarf planets eris, pluto, humea, makemake and ceres

​Earth

​earth is the only planet in the solar system known to support life. it is a beautiful planet composed of water and land. the earth in unlike every other planet in the solar system. it is the only planet that has an atmosphere containing 21 percent oxyzen. it is the only planet that has liquid water on surface

​inside the earth

​now, we will study about the layers of earth

1) crust: it is the outermost layer of earth the thickness of a crust varies from around 5 km in ocean floor, 70 km on the land.

​2) mantle: the mantle is the second layer of the earth, almost 3000km deep. it is mainly made up of magnesium and iron, and the molten rocks form magma

​3) the core has 2 layers, outer and inner outer is about 2300 m thick made up of iron and nickel, it is so hot that that the iron and nickel exist here in molten state. the inner is about 1200 km thick. it is solid ven though it is the hottest part of the earth