Olympiad Test Level 1: Our Earth and Universe- 2 - Class 6 MCQ

Jupiter, like Venus, has an axial tilt of only 3 degrees, so there is literally no difference between the seasons. However, because of its distance from the sun, seasons change more slowly. The length of each season is roughly three years.

• White dwarf: When a star has completely run out of hydrogen fuel in its core and lacks the mass to force higher elements into fusion reaction, it becomes a white dwarf star. 
• Red dwarf: Red dwarf stars are the most common kind of stars in the Universe. These are main sequence stars but they have such low mass that they’re much cooler than stars like our Sun. The smallest red dwarfs are 0.075 times the mass of the Sun, and they can have a mass of up to half of the Sun.
• Red giant: A red giant is a star that is past its peak and has consumed its core's supply of hydrogen fuel. As a result, helium has built up in the core, hydrogen has fused in the outer shells, and the star has expanded into a giant red monstrosity.

• Red dwarf stars are the most common kind of stars in the Universe. These are main sequence stars but they have such low mass that they’re much cooler than stars like our Sun. The smallest red dwarfs are 0.075 times the mass of the Sun, and they can have a mass of up to half of the Sun. 
• At 4.2 light years away Proxima Centauri is the nearest star to the sun. It is a very small red dwarf with a radius of around 97,000 km, which is around 14% the size of our sun.

The ocean holds about 97 percent of the Earth's water; the remaining three percent is distributed in many different places, including glaciers and ice, below the ground, in rivers and lakes, and in the atmosphere. At any given time only about 0.001 percent of Earth's water is in the form of atmospheric vapour, a surprisingly small number given its crucial role in weather.

The crust is the outermost layer of the Earth’s surface, where we live. The thickness ranges from 0 to 60 kilometres.
It’s a solid rock layer that comes in two varieties:

• Continental crust covers the land
• Oceanic crust covers water

Earth's rotation or Earth's spin is the rotation of planet Earth around its own axis, as well as changes in the orientation of the rotation axis in space. Earth rotates eastward, in prograde motion. As viewed from the northern polar star Polaris, Earth turns counterclockwise.

The earth takes exactly 365 days and 6 hours to complete one revolution which is equal to approximately 365 days.

Eclipses of the Moon happen at full Moon, when the Sun, Earth and Moon are aligned to form an exact or an almost straight line.

A lunar eclipse only occurs during a full Moon, when the Sun, Earth, and Moon are all aligned. But despite the Moon only taking 29.5 days to orbit Earth and complete a cycle from full Moon to full Moon, there are only on average about three lunar eclipses every year.

The Earth rotates on its axis. As rotation occurs, only one-half of the Earth faces the Sun and that has day while the other has night. This causes us to experience day and night. Thus, the rotation of the Earth gives rise to day and night.

• The earth we live on is a sphere that rotates daily on its axis.
• The axis is an imaginary line that runs through the center of the earth from top to bottom.
• It passes through both the North and the South Poles.
• The Poles are imaginary points marking the "top" and "bottom" of our earth.

Mercury is the smallest planet in the Solar System and the closest to the Sun. Its orbit around the Sun takes 87.97 Earth days, the shortest of all the Sun's planets.

The Hemispheres of the Earth in geography and cartography refer to any division of the globe into two hemispheres.
The most common such divisions are by latitudinal or longitudinal markers:

• North-South: Northern Hemisphere, the half that is north of the equator
  Southern Hemisphere, the half that lies south of the equator
• East-West: Eastern Hemisphere, the half that lies east of the prime meridian and west of the 180th meridian
  Western Hemisphere, the half that lies west of the prime meridian and east of the 180th meridian

Over half of the 88 constellations, the IAU recognizes today are attributed to ancient Greek, which consolidated the earlier works by the ancient Babylonian, Egyptian and Assyrian.

Mercury is the smallest planet in the Solar System and the closest to the Sun. Its orbit around the Sun takes 87.97 Earth days, the shortest of all the Sun's planets.