Free Astronomy and Space MCQs with Answers

71. Asteroids are made mostly of?

• A. Rock, metal, ice and dust
• B. Rock and metal
• C. Metal and gas
• D. Metal, gas and rock

Explanation: Most asteroids are rocky or metallic bodies, unlike comets, which contain much more ice and dust. Gas is not a major constituent of typical asteroids.

72. Comets are often called what?

• A. Dusty snowballs
• B. Filthy snowballs
• C. Dirty snowballs
• D. Impure snowballs

Explanation: Comets are popularly called dirty snowballs because they contain frozen volatile substances mixed with dust and rocky material. Their icy surfaces produce the coma and tail when heated by the Sun.

73. As comets get close to the sun, they start to "melt" and release gas and dust. This gas and dust forms what?

• A. "coma" around the comet's nucleus and a long tail that points away from the sun
• B. "coma" that points away from the sun and a long tail around the comet's nucleus
• C. Only "coma" around the comet's nucleus
• D. Only a long tail that points away from the sun

Explanation: Solar heating causes a comet's ices to sublimate, forming a coma around its nucleus and a tail directed generally away from the Sun by sunlight and the solar wind. The tail does not simply trail behind the comet's path.

74. Comets are made mostly of ______________?

• A. Ice and dust
• B. Dust and lights
• C. Ice, dust and lights
• D. All of the above

Explanation: A comet's nucleus is mainly a mixture of ice and dust, with frozen gases and rocky grains also present. “Lights” is not a material from which comets are made.

75. Comets are made mostly of ice and dust. As comets get close to the sun, they start to "melt" and release what?

• A. Steam and dust
• B. Gas and dust
• C. Steam, gas and dust
• D. None of the above

Explanation: Near the Sun, cometary ices sublimate directly into gas, carrying dust away from the surface. The visible release is therefore gas and dust rather than ordinary steam alone.

76. The moon's surface has been explored by how many astronauts?

• A. 10
• B. 11
• C. 12
• D. 13

Explanation: Twelve astronauts walked on the Moon during the six successful Apollo landing missions, from Apollo 11 through Apollo 17. Several other astronauts orbited the Moon but did not land.

77. The moon has a large, circular basin called _____________?

• A. the Simerian Basin
• B. the Inbrium Basin
• C. the Imbrium Basin
• D. Black Bowl Basin

Explanation: The Imbrium Basin is the large impact basin associated with the Moon's Mare Imbrium. “Inbrium” is a common spelling trap caused by misplacing the first consonant.

78. Which one of the following is true?

• A. The moon has both atmosphere and magnetic field
• B. The moon has no atmosphere or magnetic field
• C. The moon has atmosphere but no magnetic field
• D. The moon has magnetic field but no atmosphere

Explanation: The Moon has no substantial atmosphere and no global magnetic field, so basic astronomy texts describe it this way. It does possess an extremely thin exosphere and small localized magnetic anomalies, but these are not treated as a normal atmosphere or planetary field.

79. The moon's surface temperature varies from about ________ to _________ ?

• A. - 173 degrees Celsius at night to 127 degrees Celsius during the day
• B. - 172 degrees Celsius at night to 172 degrees Celsius during the day
• C. Remains constant during day and night
• D. - 170 degrees Celsius at night to 107 degrees Celsius during the day

Explanation: With virtually no atmosphere to distribute heat, the lunar surface becomes extremely cold at night and very hot in daylight, roughly from −173°C to 127°C. This large contrast is much greater than on Earth.

80. Which of the following was first to be discovered in the chromospheres of the sun?

• A. Krypton
• B. Xenon
• C. Neon
• D. Helium

Explanation: Helium was first identified through a spectral line in the Sun's chromosphere before it was discovered on Earth. Its name comes from Helios, the Greek name for the Sun.