Cosmos: A Spacetime Odyssey, Episode 12 - The World Set Free

The episode begins by describing Venus as a world that may once have been

• frozen solid
• much like Earth
• covered in forests
• smaller than Mars

Today, Venus is extremely hot mainly because

• it is much closer to the Sun than Earth
• its clouds let in too much sunlight
• carbon dioxide traps heat in its atmosphere
• it has no atmosphere

The episode says Venus’s clouds are made mostly of

• water vapor
• methane
• nitrogen
• sulfuric acid

On Earth, most carbon is stored in

• carbonate rocks
• the upper atmosphere
• ocean waves
• volcanoes

The White Cliffs of Dover were built over time mainly by

• lava flows
• wind erosion
• tiny marine organisms
• glaciers

The episode says Earth needs some carbon dioxide because without it

• Earth would be a snowball
• the oceans would boil
• plants would stop growing instantly
• volcanoes would stop erupting

Charles David Keeling is important in the episode because he

• discovered Venus's atmosphere
• measured carbon dioxide in the atmosphere accurately
• invented the first solar collector
• landed a spacecraft on Venus

Ice cores from Greenland and Antarctica are useful because they contain

• ancient air trapped in the ice
• ancient fossils of dinosaurs
• volcanic lava layers
• pieces of meteorites

The episode says atmospheric CO2 is now more than

• 10% higher than before the industrial revolution
• 20% higher than before the industrial revolution
• 40% higher than before the industrial revolution
• 80% higher than before the industrial revolution

The greenhouse effect works because carbon dioxide

• reflects all sunlight back into space
• absorbs outgoing heat radiation
• creates oxygen in the air
• blocks volcanoes from erupting