Where Did Earth's Water Come From?

Earth's surface is unexpectedly rich in water, despite its formation in a hot, dry inner solar system. The solar system formed from a dust and gas cloud, with the sun's solar wind pushing away lighter elements, leaving rocky planets. Water couldn't have been part of Earth's initial formation due to high temperatures. It likely arrived from outer solar system bodies like meteoroids. Comets were ruled out due to their heavy hydrogen content. Carbonaceous chondrites, a type of meteorite, are the most probable source, as they contain water with a similar heavy hydrogen ratio to Earth's, suggesting they brought water to our planet.

What was the primary reason Earth was initially dry according to the solar system's formation story?

• The presence of a dense atmosphere

• The absence of a magnetic field

• The lack of solid particles

• The high temperatures and solar wind

What process is NOT responsible for creating or destroying water on Earth?

• Erosion

• Breathing

• Photosynthesis

• Combustion

Why were comets ruled out as the source of Earth's water?

• They never reached Earth

• Their water has a different heavy hydrogen content

• They are too small to have contributed significantly

• They contain no water

What is the significance of heavy hydrogen in determining the source of Earth's water?

• It helps identify the chemical signature of the water source

• It reveals the water's pH level

• It indicates the age of the water

• It shows the water's temperature

What is a key characteristic of carbonaceous chondrites that makes them a likely source of Earth's water?

• They have no hydrogen content

• They are composed entirely of metal

• They are found only on the Moon

• They contain water and carbon