Which planetary body has an atmosphere that is mostly carbon dioxide and lacks thick oceans?

Which planetary body has an atmosphere that is mostly carbon dioxide and lacks thick oceans?

• A. Mars
• B. Neptune
• C. Earth
• D. Venus

Answer: (D)

Dominant atmospheric gas and the presence of surface oceans shape a planet’s climate. Venus has a very thick atmosphere dominated by carbon dioxide, which traps heat incredibly well. That runaway greenhouse effect keeps the surface extremely hot and prevents liquid water from existing, so there are no thick oceans. The other worlds don’t fit both conditions: Earth has oceans and a nitrogen–oxygen atmosphere; Mars has some CO2 in its atmosphere but it’s thin and lacks global oceans; Neptune is a gas giant with a mostly hydrogen–helium envelope and no surface oceans. So Venus best matches a atmosphere mostly carbon dioxide with no thick oceans.

Dominant atmospheric gas and the presence of surface oceans shape a planet’s climate. Venus has a very thick atmosphere dominated by carbon dioxide, which traps heat incredibly well. That runaway greenhouse effect keeps the surface extremely hot and prevents liquid water from existing, so there are no thick oceans. The other worlds don’t fit both conditions: Earth has oceans and a nitrogen–oxygen atmosphere; Mars has some CO2 in its atmosphere but it’s thin and lacks global oceans; Neptune is a gas giant with a mostly hydrogen–helium envelope and no surface oceans. So Venus best matches a atmosphere mostly carbon dioxide with no thick oceans.