Test: Introduction To Earth & Universe (Previous Year Questions) - UPSC MCQ

The Earth is the densest of all planets in the Solar System.  The predominant element in the composition of the Earth is Iron (36 %) and in the Earth’s crust is oxygen (45 %).  The Sun contains 99 % of the mass of the solar system.  The diameter of the sun is 109 times that of the Earth.

The average distance between the sun and the Earth is known as Astronomical Unit (1AU= 150 x 10⁶ kms)

Asteroids are rocky remains left over from the formation of the solar system. Most asteroids orbit the sun in a girdle between Mars & Jupiter. Scientists believe there are possibly millions of asteroids, arraying extensively in size from hundreds of kilometers across to less than 1 kilometer broad. Asteroids' orbital paths are inclined by the gravitational haul of planets, which cause their paths to change. Scientists consider wandering asteroids or fragments from past collisions have knocked into Earth in the past, playing a key role in the development of our planet.

Difference between asteroids and comets lies mainly in their composition. Both were formed during the early phase of the solar system. Asteroids consist mainly of rocky and metallic material, while comets comprise if ice, frozen gases, dust and rocky and metallic material.

Asteroids are found nearer to the Sun while comets are found farther from the Sun as the heat can melt away comet's ice. In fact, when a comet approaches the Sun, it starts losing its ice because of the Sun's heat as a result of which a perceptible glowing tail can be seen. 

If the Stars are seen to rise perpendicular to the Horizon by an observer, he is located on the Equator.

Black holes are stars which have contracted so much that they have developed Super density.  Their Gravitational pull is so strong that even the light of radiation produced by them cannot escape.  They cannot be seen with the help of optical Telescope.  It is the smallest and the densest object in the Universe. 

Existence of human life on Venus is highly improbable because its atmosphere contains around 95% of Carbon dioxide and has a pressure 100 times the pressure of the Earth’s atmosphere.

  Jupiter takes 11.86 years to complete one Revolution around the sun.

The water cycle also known as the hydrological cycle, describes the continuous movement of water on, above and below the surface of the Earth.

Venus is called the twin of the Earth.

Venus, has its orbit closest to the Sun.

The surface temperature of the sun is estimated as 5778K (6000 degree C)

Of the Terrestrial planets, Mercury or Venus has any moon at all.

Mars is called the ‘Red Planet’ of our Solar System.

Venus is the brightest planet in our solar system.

The Milky Way Galaxy was first observed by Galileo Galilei

Since 2006, per the International Astronomical Union's planetary criteria, Pluto isn't considered a planet because it hasn't cleared the neighborhood around its orbit of other objects. However, it does meet IAU's criteria for what constitutes a dwarf planet.  Pluto was discovered by Clyde Tombaugh in 1930. Pluto has been given the number 134340.

Venus is the hottest planet in our solar system because of its proximity to the sun and its dense atmosphere.

The largest planet in our solar system is Jupiter and has a mass 300 times as that of the Earth.

Jupiter, Saturn, Uranus, Neptune, Earth, Venus, Mars and Mercury are the planetary arrangement in terms of surface area.