Free Astronomy and Space MCQs with Answers

21. In general, Comets have __________ orbits

• A. Elliptical
• B. Highly elliptical
• C. Circular
• D. Parabolic

Explanation: Most comets follow highly elliptical orbits, travelling far from the Sun and returning after a period. Some long-period comets may have nearly parabolic paths, but that is not the general answer.

22. The planet that moves round the Sun at the highest speed is_________?

• A. Jupiter
• B. Venus
• C. Mars
• D. Mercury

Explanation: Mercury moves fastest around the Sun because it is the closest planet and has the shortest orbital period, about 88 Earth days. Its average orbital speed is higher than that of the other listed planets.

23. The nearest planet to the Earth is _________?

• A. Venus
• B. Mercury
• C. Mars
• D. Moon

Explanation: Venus is traditionally identified as Earth's nearest planet because it can come closer to Earth than any other planet. Mercury is the closest planet to the Sun, which makes it a tempting but incorrect choice here.

24. The most abundant element in the universe is __________.

• A. Oxygen
• B. Hydrogen
• C. Carbon Dioxide
• D. Silicon

Explanation: Hydrogen is the most abundant element in the universe, making up most of the material in stars and much of the interstellar gas. Oxygen and silicon are far less abundant cosmic elements.

25. The Sun is a __________?

• A. Star
• B. Planet
• C. Asteroid
• D. Meteor

Explanation: The Sun is a star because it produces its own light and heat through nuclear fusion. Planets and asteroids only reflect light from a star.

26. Which is the outermost planet in the solar system?

• A. Mercury
• B. Pluto
• C. Neptune
• D. Uranus

Explanation: Neptune is the outermost of the eight officially recognized planets. Pluto lies farther out at times but is classified as a dwarf planet, not a full planet.

27. Who discovered Uranus__________?

• A. William Caxton
• B. John Davise
• C. Herschel
• D. Shellay

Explanation: William Herschel discovered Uranus in 1781 while conducting telescopic observations. The other names listed are not associated with its discovery.

28. How many layers does sun have ?

• A. 6
• B. 4
• C. 7
• D. 3Chemistry

Explanation: The Sun is commonly described as having six layers: core, radiative zone, convection zone, photosphere, chromosphere and corona. The three inner regions form its interior, while the outer three are its visible atmosphere.

29. On the Moon, the escape velocity is: __________?

• A. Less than on Earth due to its lower mass and smaller radius
• B. More than on Earth due to its smaller radius
• C. The same as on Earth because escape velocity is a constant
• D. Dependent on the time of day

Explanation: The Moon’s escape velocity is about 2.38 km/s, compared with about 11.2 km/s for Earth. Its much smaller mass more than offsets its smaller radius, making escape easier.

30. Escape velocity depends on ________?

• A. Mass of the object trying to escape
• B. Radius of the planet or celestial body
• C. Both mass and radius of the planet or celestial body
• D. The velocity of the rotating planet

Explanation: Escape velocity depends on the mass and radius of the attracting celestial body, according to vₑ = √(2GM/R). It does not depend on the mass of the object trying to escape.