A.1.1.7-1.8 Origins of Water on Earth

Front

What percentage of Earth's water is in a liquid state?

Back

98.3% of Earth's water is in a liquid state.

Tags

NGSS.HS-ESS2-5

Front

Why is it unlikely that water was on Earth when the planet was formed?

Back

Because temperatures would have been above 100°C, causing water to boil and be lost to space.

Tags

NGSS.HS-ESS1-6

Front

What is the most widely supported hypothesis for the origin of Earth's water?

Back

Water was delivered to Earth by colliding asteroids.

Tags

NGSS.HS-ESS2-5

Front

How often do large asteroids collide with Earth currently?

Back

Large asteroids (with a diameter greater than 5 km) collide with Earth about once every 20 million years.

Front

Why can't the current rate of asteroid bombardment account for all of Earth's water?

Back

Because a sample from an asteroid contained only a small proportion of water, and there is evidence of heavier bombardment in Earth's early history.

Front

What factors help retain water on Earth after its delivery by asteroids?

Back

The Earth's distance from the Sun prevents water from boiling, and Earth's strong gravity holds water and gases in the atmosphere.

Tags

NGSS.MS-ESS2-4

Front

What is the Goldilocks zone?

Back

The habitable zone around a star where the temperature allows water to exist in a liquid state.

Front

How does the Goldilocks zone relate to the potential for extra-terrestrial life?

Back

The more planets in the Goldilocks zone, the greater the chance that extra-terrestrial life has evolved.