Celestial bodies
Figure 1 Celestial Bodies Astronomy
The Moon
The Phases of the MoonFigure 2 Phases of the Moon
Blue moon – Generally there occurs one New Moon every month. However, at times, there can be two new moons in a single month. The second New Moon in a month is called the Blue Moon. The phases of the Moon hold an importance in the Indian society and culture as different festivals in India are celebrated depending upon the Phases of the Moon.
The surface of the Moon
Figure 3 Surface of the Moon Can we hear sound on the Moon?There is no atmosphere on the Moon that is, no gases are present on the Moon that could act as a medium for the propagation of sound. Hence, the astronauts of the Moon cannot hear each other. They generally use signs or microphones to communicate with each other. Who was the first Astronaut to land on the moon?Neil Armstrong was the first person to land on the moon followed by another Astronaut Edwin Aldrin. Neil Armstrong landed on the moon on July 21 1969. What is a lunar eclipse?
Figure 4 Lunar Eclipse The Stars
Figure 5 There are millions of stars in the universe Why do stars twinkle?Stars emit light that when enters the earth surface has to travel through the several layers of the earth’s atmosphere. Hence, it appears that the light is travelling in a zig-zag motion due to the change in densities of the earth’s atmosphere and the density of the space. Therefore, it appears to us as if the stars are twinkling. Why Sun is a Star?
Distance between the Sun and the Earth
Light Year
Why are stars invisible during the daytime?Stars are present in the sky during the day as well as night time. However, during the daytime, the sunlight is so bright that it becomes difficult to locate stars in the sky. Can stars change their positions?If we observe a star or a group of stars for some hours their position appears to change. This is because of the motion of the earth. The earth keeps on revolving around the sun and hence changes its position with respect to the stars. Why stars appear moving from east to west?The rotation of the Earth takes place in a direction from west to east. To us, it appears as if the earth is still and the sky is moving from east to west direction. However, it is not true. Also, this is the same reason why the sun appears to rise from the east and set in the west. The significance of the Pole StarThe pole star also called as Polaris is situated close to the earth's axis of rotation. As a result, the position of the pole star appears to be fixed. This is unlike the other stars as their position keeps on changing with respect to the earth. Figure 6 Pole Star Constellations
Figure 7 A constellation Major Constellations1. Ursa Major or the Great Bear or Saptarishi or the Big Dipper
Figure 8 Ursa Major Significance of SaptarishiThe seven stars in the Ursa Major constellation are believed to signify seven saints according to the Indian mythology. These seven Saints are believed to preserve the knowledge of the Vedas that they propagate to people in every new age. Figure 9 Saptarishi How can we locate pole star using Ursa Major?Figure 10 Locating Pole Star using Ursa Major
2. Orion or the HunterFigure 11 Orion
Sirius StarFigure 12 Locating Sirius Star using Orion
3. CassiopeiaFigure 13 Cassiopeia
4. Leo MajorFigure 14 Leo Major
The Solar SystemFigure 15 The Solar System
The PlanetsFigure 16 the Planets
Why do planets not fall into the sun? We know that the sun exerts a gravitational force on all the planets. But they do not fall into the sun because they are also revolving around the sun in a fixed path. This revolution prevents them from falling off into the sun. Mercury
Venus
Earth
Orbital and Equatorial Plane of the EarthFigure 17 Earth rotates on tilted axis Orbital Plane of the EarthWe know that earth revolves around the Sun in an orbit. The plane in which it revolves around the Sun is called its orbital plane. Equatorial Plane of the EarthThe Equator is an imaginary line drawn from the middle of the earth. The plane of the equator is called the equatorial plane. The equatorial plane and the orbital plane of the earth are inclined at an angle of 23.5o. Hence, the axis of the earth is tilted at an angle of 66.5o to the orbital plane. Figure 18 Change in Seasons Due to Earth's tilted axis Mars
What is Mangalyaan?Mangalyaan is an Orbiter launched by ISRO (Indian Space Research Organisation) that orbits around Mars. It was launched in November 2013 and was placed in its orbit around the Mars in September 2014 successfully. India is the first country that could place an orbital in its orbit in the first attempt. Jupiter
Saturn
Uranus
Neptune
Figure 19 Period of Rotation, Revolution and Distance of all the Planets Inner and Outer PlanetsThe first four planets of the solar system are called inner planets. These planets have few moons of their own. The planets after Mars are called outer planets of the solar system. All these planets have a ring system around them and possess a large number of moons. What are the differences between stars and planets?Figure 20 Differences between stars and planets Other Members of the Solar SystemAsteroidsFigure 21 Asteroids in Space
Figure 22 Asteroid Belt CometFigure 23 A comet
Meteoroids and MeteorsFigure 24 A meteoroid approaching Earth
Figure 25 A meteor is the sky Meteor ShowerFigure 26 Meteor Shower When the earth crosses a comet's tail a large number of flying meteors can be observed in the sky. This is called a Meteor shower. Certain meteor showers occur periodically in the sky. Artificial satellitesFigure 27 Artificial Satellite These are the man-made satellites that are sent out into space to revolve around the earth. They orbit nearer to the earth as compared to the moon. Functions of artificial satellites:
Some Indian Artificial Satellites of the Earth:
How artificial satellite is different from a natural satellite?
Figure 28 Natural Satellites of the solar system You Might Like to Refer: online study 10th class | best online coaching for cbse class 10 What is the sun in short?Our Sun is a 4.5 billion-year-old star – a hot glowing ball of hydrogen and helium at the center of our solar system. The Sun is about 93 million miles (150 million kilometers) from Earth, and without its energy, life as we know it could not exist here on our home planet.
What is the sun simple answer?The Sun is the star at the center of the Solar System. It is a nearly perfect sphere of hot plasma, with an internal convective motion that generates a magnetic field via a dynamo process. It is by far the most important source of energy for life on Earth.
Why is sun a star class 8?Answer: The Sun is also called as star because it has its own source of energy and it continuously emits light and heat.
What is planet in Class 8?A planet is a large celestial body that revolves around the sun in fixed orbits. Planets do not have any light of their own but reflect the light of the sun. Planets also do not twinkle like stars because they are much closer to us.
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