Length of a Day on Each Planet

• 04 Nov 2019

Why in News

• Recently, the research was undertaken to calculate the accurate length of a day on Venus and Saturn which has been changing since 1963.
  
  • Venus:
    
    • The recent observation of the Magellan spacecraft’s observations (1991) concluded that the rotation period for Venus has an uncertainty of about 9 seconds.
  • Saturn:
    
    • The recent, the Cassini spacecraft showed that there is an uncertainty of 6 minutes with a rotation period of Saturn.

The Solar System

• The Solar System consists of the Sun and eight planets.
  
  • It also consists of bodies such as comets, asteroids, and meteors.

Planets vs Dwarf Planets

• The definition of a planet was adopted by the International Astronomical Union in 2006. A planet must:
  
  • Orbit a star (in our system, it is the Sun).
  • Be big enough to have enough gravity to force it into a spherical shape.
  • Be big enough that its gravity cleared away any other objects of a similar size near its orbit around the Sun.
• On the other hand, dwarf planet is a celestial body orbiting a star that is massive enough to be rounded by its own gravity but has no clear orbit (Gravitationally not dominant in its orbit).

Planets	Facts
Mercury	It is the nearest to the Sun and also the smallest planet in our solar system. It has no satellite of its own. It takes 1408 hours to complete a rotation.
Venus	It is called morning or an evening star, although it is not a star. Sometimes it is called as Earth’s twin. Venus has no moon or satellite of its own. It rotates from east to west while the Earth rotates from west to east. It takes 5,832 hours to complete a rotation.
Earth	The Earth is the only planet in the solar system on which life is known to exist. The axis of rotation of the Earth is 23.5 degrees relative to the orbital plane – the plane of Earth’s orbit around the sun. The tilt is responsible for the change of seasons on the Earth. The Earth has only one moon. The Earth takes 24 hours to complete a rotation.
Mars	It appears slightly reddish and, therefore, it is also called the red planet. Mars has two small natural satellites. It takes 25 hours to complete a rotation.
Jupiter	Jupiter is the largest planet of the solar system. Jupiter has 53 named satellites and another 26 awaiting official names. It also has faint rings around it. It takes only 10 hours to complete a rotation.
Saturn	The Saturn is yellowish in colour. It has an icy ring around it. It has more than 60 known moons. It takes 11 hours to complete a rotation (second-shortest day in the solar system).
Uranus	Uranus also rotates from east to west (like Venus). It has a highly tilted rotational axis. It takes 17 hours to complete a rotation.
Neptune	It is the eighth and most distant planet in our solar system. The Neptune is dark, cold and has a presence of supersonic winds. It takes 16 hours to complete a rotation.

Source: IE