5. Inner planets: Mercury and Venus

Mercury (Budh) is the nearest planet to the Sun. It is the smallest planet without any satellite of its own. It is difficult to observe this planet since it is hidden in the glare of the Sun. But still, it can be observed near the horizon just before sunrise or after sunset. This planet looks grey in colour.

 

 

The rotation period is $59\ days$, and the period of revolution is $88\ days$. Since this planet revolves around the Sun in $88\ days$, it is considered the fastest planet in the solar system.

Venus (Shukra) is the nearest neighbour planet of Earth which does not have any satellite of its own. Venus is the 'Twin of the Earth' due to its similarities in size and surface composition of the Earth.

 

 

Rotation:
All the other planets rotate in the anti-clockwise direction from west to east. But, Venus rotates in the clockwise direction, i.e., from east to west. On this planet, the Sun rises from the west and sets in the east. This planet completes its rotation in $243\ days$, and the period of revolution is $225\ days$.

 

Hottest planet:
Even though Mercury is present near the Sun, Venus is the hottest planet in the solar system. This is because Venus has a thick atmosphere composed of carbon-di-oxide and clouds of sulphuric acid. These gases in the atmosphere trap the heat produced by the Sunlight falling on the Venus and retains the heat inside. This makes the planet hot.

 

Appearance in the sky:
Due to the thick atmosphere of the planet, the light falling on the clouds gets reflected in the sky and appears as the brightest planet.

 

 

Before sunrise, this brightest planet appears in the eastern sky, whereas, after sunset, it appears in the western sky. Hence, it is also called a morning star or an evening star.

 

Venus appears yellowish in colour. The visibility time of Venus in the sky is found in a newspaper or from an almanac. With the help of a telescope, it can be easily found in the sky either $1\ −3$ $hours$ before sunrise or after sunset. Like Moon, the Venus also shows different phases.