Stars And The Solar System Chapter 17 Extra Questions

(i)A meteoroid is a small rocks moving in space.
(ii)A comet is a celestial object that consists ice, dust and rocks. It is continuously moving in our solar system. For example, Halley’s Comet.
(iii)The largest meteorite found on earth is “The Hoba Meteorite” weighing 66 tonnes.
(iv)A collection of large asteroids forming an orbital revolving around the sun between Mars and Jupiter is called asteroid belt.
(v)Saturn is known as a ringed planet because it has a ring around it which makes more beautiful.

The observation of distant celestial bodies in space required a telescope, artificial satellite and space radiator devices, such as flat-plate radiators. Therefore, Tarantino needs these space probes to complete his project.

1 au= 1.496 x 10⁸ km
10 x 1.496 x 10⁸ km = 1.496 x 10⁹ km

Distance between the earth and star X = 2250 ly
1 ly = 9.461 x 10¹² km
2250 x 9.461 x 10¹² km = 2.128725 x 10¹⁶ km

The difference between Ursa major and Ursa minor is given in the table below: -

Ursa major	Ursa minor
It is known as a Great Bear.	It is known as Little Bear.
Vrihat Saptarishi Mandal	Laghu Saptarishi Mandal
It contains all seven stars of Ursa minor including some other stars.	It is a part of Ursa major.

The sun is considered as a parent star for the earth because the imaginary orbital of the earth designs in such a way that results the earth revolving around the sun. Moreover, there are eight planets including the earth and some dwarf planets revolve around the sun and form a solar system. Therefore, the sun is known as a parent star for all the planets revolving around it.

Stars are luminous celestial bodies present in space. For example, Alpha Centauri and Sirius.

Natural satellite is a celestial body that revolves around its planet. For example, Ganymede and Miranda.

An artificial satellite is a man-made satellite used for communication and sending pictures of the celestial bodies in space. For example, Arybhatta and Sputnik-1.

Our solar system consists of the sun and the following major planets surrounding it are: -
Mercury: It is the nearest and the smallest planet to the sun. It takes 88 days to complete one revolution around the sun and 59 to complete one rotation on its axis. It does not have any satellite.
Venus: It is the second closest planet to the sun. It takes 225 days to complete one revolution around the sun and 243 days to complete one rotation on its axis. It revolves anti-clockwise, which means opposite direction to the sun as compared to the direction of the earth. It is also known as morning and evening star because it can be easily spotted before sunrise and after sunset.
Earth: It is the unique planet of all universe because it is only planet that has life on it. The earth takes 365 days to complete one revolution around the sun and 24 hours to complete one rotation on its axis.
Mars: It is also known as “Red Planet” because it is made up of red soil which contains ferric oxide. It is the fourth closest planet to the sun. It takes 687 days to complete one revolution around the sun and 24 hours to complete one rotation on its axis.
Jupiter: It is the largest planet of our solar system. It takes 4331 days to complete revolution around the sun but only 10 hours to complete one rotation on its axis. It has 53 known satellites and 26 unknown satellites.
Saturn: It is the second largest planet of our solar system. It is made up of iron and nickel, and surrounded by liquid hydrogen and helium. It has a beautiful ring around it, which can be seen under powerful telescope like Hubble. It takes 30 years to complete one revolution around the sun but only 11 hours to complete one rotation on its axis.
Uranus: It is the coldest planet of our solar system. It is made up of methane, ammonia and water. It takes 84 years to complete one revolution around the sun but only 17 hours to complete one rotation on its axis.
Neptune: It is the densest planet of our solar system. It is made up of methane, hydrogen and helium. It takes 165 years to complete one revolution around the sun but only 16 hours to complete one rotation on its axis.  

The moon changes its shape everyday due to its relative motion with respect to the earth and the sun. The visibility of the moon varies due to its relative motion that appears in different shapes observed from the earth. These different shapes of the moon that can be seen from the earth are called the phases of the moon. When the moon is present between the sun and the earth then it is farther side is lit while the nearer side becomes dark. This condition is called a new Moon. After the new Moon, the shape of the moon is visible as crescent shape and also considered as a waxing crescent. After the crescent moon, the next phase of the moon appears to be the half-moon condition where the half of the moon is visible from the earth. This phase is also called first quarter. After the first quarter, the moon appears to be 75% visible from the earth, which means only some portion of the moon is dark. This phase of the moon is called waxing gibbous. After the waxing gibbous, the full moon is visible from the earth. It is a continuous repeating process.