Olympiad Test Level 1: Our Earth and Universe- 1 - Class 6 MCQ

Ganymede is the largest satellite in the solar system. Discovered by Galileo in the year 1610, Ganymede is a satellite of Jupiter. It has a diameter of around 5260 km making it larger than the planet Mercury.

The Andromeda Galaxy, also known as Messier 31 or M31, is a spiral galaxy located about 2.5 million light-years from Earth. Located in the Andromeda constellation, it is the closest spiral galaxy to the Milky Way, where our solar system is. It is also the largest galaxy of what is called the Local Group which is a collection of more than 54 galaxies including the Milky Way.

Mars is a cold desert world and is half the size of Earth. Mars is sometimes called the Red Planet because of rusty iron in the ground. Mars has a very thin atmosphere composed mostly of the tiny amount of carbon dioxide (95.3%), nitrogen (2.7%), argon (1.6%) and traces of oxygen (0.15%) and water (0.03%).

• The surface of the moon is covered in huge dark spots, visible from Earth even with the naked eye. These patches are known as Maria - a Latin word meaning 'seas'. 
• Maria are huge basins containing lava flows marked by craters, ridges, faults, and straight and meandering valleys called rilles and are devoid of water. They were formed beginning about 3.9 billion years ago during a period of intense bombardment by asteroid-sized bodies. 

This solid metal ball has a radius of 1,220 kilometers (758 miles) or about three-quarters that of the moon. It's located some 6,400 to 5,180 kilometers (4,000 to 3,220 miles) beneath Earth's surface. Extremely dense, it's made mostly of iron and nickel.

For practical understanding, you can perform the experiment given below:

• Take a torch, switch it on and place it on a table.
• Stand in front of the source of light of the torch.
• Take a small ball and hold it at a height same as that of the torch and facing the torch.
• You will notice that the ball appears dark.
• Now if you change the position of the ball, keeping the height same, you will notice that only some part of the ball appears illuminated.
• If you place it diametrically opposite to the torch, but at height slightly higher than your head, the entire ball gets illuminated.
• You can also notice that when the ball appears completely dark, the ball is closest to the torch.
• The phases of the moon are due to situations similar to this experiment. 
• In this experiment, you represent the earth, the torch represents the sun and the ball the moon.
• You can see that the changes in appearance of the ball are caused by movement of the ball around you.

Although the moon appears to change shape, it is actually always a sphere. In addition, although the apparent shape and location of the moon change from night to night, we always see the same side of the moon.

The Moon is Earth's only natural satellite. At about one-quarter the diameter of Earth, it is the fifth largest satellite in the Solar System, the largest satellite in the Solar System relative to its major planet, and larger than any known dwarf planet.

The Moon blocks the light of the Sun and a shadow of the Moon is cast on the Earth's surface. This is an eclipse of the Sun or a solar eclipse.
There are three types of solar eclipse: Total, partial, and annular. During a total eclipse, the Moon completely covers our view of the Sun.

During the Northern Hemisphere's summer solstice which always falls around June 21, the Southern Hemisphere gets its winter solstice. Likewise, during the Northern Hemisphere's winter solstice which always falls around December 22, the Southern Hemisphere gets its summer solstice.