Tag: the earth and the graticule

• Planet Earth has been called the "Blue Planet" due to the abundant water on its surface. 
• Here on Earth, we take liquid water for granted; after all, our bodies are mostly made of water.
• However, liquid water is a rare commodity in our solar system.

• Planet Earth has been called the 'Blue Planet' due to the abundant water on its surface.

• Of the eight planets in the solar system, the fifth-largest planet is Earth.

• Asia is the largest and Australia is the smallest continent.

Large and continues land masses on surface of the earth are termed as continents. This division on the earth as continents are done by us. Our planet is divided into seven large continental masses, these are, Asia, Europe, Africa, North America, South America, Australia and Antarcatica. Among them Asia is the largest and Australia is the smallest continent.

In carboniferous period all the land masses were united together in the form of one land mass which was named as Pangaea. There were several smaller inland seas  scattered over Pangaea which was surrounded by a huge water body named as Panthalasa representing Pacific Ocean. Luratia consisting of present North America, Europe and Asia formed norther part of Pangaea while Gondwanaland consisting of South America, Africa, Madagascar, Peninsular India, Australia and Antarctica represented the southern part of Pangaea. South pole was located near present Durban.

The shape of the earth seems like a sphere, although it is not perfectly spherical. It is rather an oblate spheroid because of the earth's diurnal rotation, i.e, the earth is slightly flattened at its polar ends and bulged out at the equatorial part.

Convection current theory of Holmes dealt with the continental drift, which led to the formation of continents as we see them today.

The formation of a rainbow involves a series of physical phenomena- reflection, refraction, dispersion and total internal reflection. The occurrence of each of these is due to the interaction of light with air and water and the boundaries between them.

Escape velocity is the minimum speed needed for an object to escape from a massive body, in the sense of becoming neither on the surface nor in closed orbit of any radius no matter how great, without the aid of thrust, or suffering the resistance from friction. The escape velocity from Earth is about $11.186$ km/s$(6.951$ mi/s; $40,270$ km/h; $25,020$ mph$)$ at the surface.