The Universe and the Solar System
Important Questions
1. Which is the largest of the inner planets?
Of the four inner planets, Earth is the largest. Arranged from the smallest to largest as Mercury, Mars, Venus, and Earth. Arranged from the distance from the sun as, from left to right, they are Mercury, Venus, Earth, and Mars.
2. What is Supernova? [SSC (10+2) 2011]
A supernova is a stellar explosion (explosion of a star) that is more energetic than a nova. During this short interval a supernova can radiate as much energy as the Sun is expected to emit over its entire life of span. The star’s luminosity increases by as much as 20 magnitudes and most of the times leaving behind a dense core.
3. Which is the smallest planet in the solar system?
Mercury is smallest planet in our solar system and nearest to the Sun, Mercury is only slightly larger than Earth’s Moon. Mercury orbits the Sun once in about 88 Earth days, completing three rotations about its axis for every two orbits.
4. Which is the outermost layer of the Sun? [SSC CGL 2011]
The outermost layer of the Sun is the corona. Only visible during eclipses, it is a low density cloud of plasma with higher transparency than the inner layers. The word corona itself derived from the Latin, meaning crown. The high temperature of the corona gives it unusual spectral features.
5. Which is the second nearest star to the Earth after the Sun? [SSC CGL 2010]
Proxima Centauri is the nearest star from our solar system. It is about 4.3 light years away from Earth. Although, it is too faint to be seen with the naked eye. Proxima Centauri’s mass is about an eighth of the Sun’s and its average density is about 40 times that of the Sun. Light takes about 4.3 years to reach us from next nearest star Proxima Centauri.
6. Which planet is called “Blue Planet’? [SSC (10+2) 2011]
Earth is the Blue Planet because of the vast encompass of oceans on its surface. From space the oceans combined with the atmosphere makes the planet look blue. There is atmosphere and water on the surface of the Earth and so, life is there on the Earth’s surface.
7. Which planet in our solar system is nearly as big as the Earth? [SSC (10+2) 2011]
Venus is sometimes called as Earth’s twin planet because its mass, density and radius are comparable to those of the Earth. Venus is also known as morning and evening star and can be seen with naked eye. In terms of size and composition, like the Earth, Venus is covered with thick clouds and hence, known as the veiled planet.
Venus is also the brightest planet in solar system. Venus is so bright partly because it reflects over 70% of sunlight striking it. It owes its reflective ability to the fact that it is blanketed with clouds. Sunlight bouncing from these clouds is what makes Venus so bright.
8. Which is the hottest planet?
Venus is the hottest planet in the solar system. Although Venus is not the planet closest to the sun, its dense atmosphere traps heat in a runaway version of the greenhouse effect that warms Earth.
9. Which is the coldest planet?
With a temperature of -357 degrees Fahrenheit, Uranus is the coldest planet in the solar system.
10. Which one of the following is called a red planet? [SSC CPO 2005]
Mars is the fourth planet from the Sun and the second smallest planet in the solar system. Named after the Roman God of war, it is often described as the ‘Red Planet’, as the iron oxide prevalent on its surface gives it a reddish appearance. It can be seen with naked eye. Mars has two Moon i.e., Fobos and Dimos.
11. Which one of the following planets has no Moon? [SSC CPO 2006]
Mercury and Venus are the only two recognised planets in our solar system without Moons because of nearness to the Sun.
12. The Moon is showing its same face to the Earth because [SSC SO 2008]
Moon revolves around the Earth in 27 days. 7 hours, 43 minutes and 11.47 seconds and rotates on its own axis in the same time That is why only one face of Moon is seen from Earth.
13. The planet emitting green light is [SSC CGL 2000]
The atmosphere of Uranus is composed of 83% hydrogen, 15% helium, 2% methane and small amounts of acetylene and other hydrocarbons. Methane in the Upper atmosphere absorbs red light, giving Uranus its blue-green colour. Most of the planets spin on its axis perpendicular, but Uranus’s axis is almost parallel to the ecliptic therefore, it receives more energy input than its equatorial regions from Sun. It has 27 Satellites.
14. Asteroids revolve round the Sun between which of the following two planets? [SSC SO 2003]
Asteroids, sometimes called minor planets, are small, rocky fragments left over from the formation of our solar system about 4.6 billion years ago. Most of this ancient space rubble can be found orbiting the Sun between Mars and Jupiter. Asteroids are made of mineral compounds, especially those containing iron, carbon and silicon. When it comes under the influence of Earth’s gravity move with great velocity towards Earth and appears as a streak of light called meteors.