Olympiad Test Level 1: Earth and Universe- 1 - Class 4 MCQ

• Venus and the planet Mercury are the only two planets that don't have a single natural moon orbiting them. Hence, Option B is correct.
• Mercury is the first planet from the sun in the solar system as well as the smallest planet among the eight planets.
• Named after the Roman god Mercury, the planet also has the shortest orbital period around the sun due to its closeness to the sun.
• As stated earlier, the planet does not have any known natural satellites.
• Just like Mercury, Venus also does not have any known natural satellites.
• Venus is the second innermost planet from the sun in the solar system.
• The planet has an orbital period of about 243 days although its orbital direction is unlike most of the other planets.

The sky appears blue because of the scattering of sunlight by the gas molecules present in our atmosphere. If there was no sun, the sky would appear black because no scattering of light will take place.

• Nicolaus Copernicus was an astronomer and mathematician who was the first to discover that the earth revolves around the sun giving birth to the heliocentric model in which the sun is at the center of the universe.
• The Copernican Revolution was very important as it deviated from the Ptolemaic model, according to which the earth stationary at the center of the universe.

Jupiter is the biggest planet in our solar system. It is a gas giant with a diameter of about 142,984 kilometers, making it much larger than Earth, Mars, or Venus.

The movement of the earth about its axis is called rotation. The earth takes about 24 hours to complete one rotation around its axis.

Jupiter rotates the fastest among all the planets in our solar system. A day on Jupiter lasts only about 10 hours, despite its enormous size. Its rapid rotation causes the planet to have a noticeable bulge around the equator.

Venus rotates the slowest of all the planets in the solar system. A day on Venus lasts about 243 Earth days, which is longer than its year (225 Earth days). Interestingly, Venus also rotates in the opposite direction to most planets, including Earth.

Uranus is the odd one out because it is an ice giant with a tilted axis of rotation (about 98 degrees), unlike Mars, Venus, and Mercury, which are rocky planets. The other three planets have more typical axial tilts and are much smaller compared to Uranus.

Mars is the fourth planet from the Sun. It is located between Earth and Jupiter and is often called the "Red Planet" due to its reddish appearance caused by iron oxide (rust) on its surface.

A celestial object is a naturally occurring unit in Universe. Stars, Planets, Natural Satellites, Comets, Asteroids, etc. are examples of celestial bodies.