Comparing Earth and Moon Reading Notes

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Comparing Earth’s and the Moon’s Features-A

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Comparing Earth and Moon – Reading Notes

When the Earth and moon first formed they were both very hot. Because the Moon is smaller and has less mass than Earth, it cooled rapidly. Deep moonquakes tell us that the moon may have a partially molten core. The Earth is almost four times larger than the moon. It did not cool completely and has a large molten core.

The Earth’s internal heat causes the crust to be broken up into moving plates. The moving plates cause earthquakes and build mountain ranges. There are only small mountains on the Moon. They are the remains of extinct volcanoes or formed when meteorites slammed into the Moon’s surface. The lowlands on the Moon (called marias) were formed from past lava flows. Maria means "seas" because the first astronomers thought the smooth, dark plains were oceans.

Only meteorites cause erosion on the Moon’s surface. They create craters and make rays that look like white streamers radiating out from the edges of craters. Craters formed on Earth by meteorites have been eroded away over time. Without an atmosphere or weather on the Moon, wind and water can not disturb its dusty and rocky surface. On the Moon no soil is produced, the sky is always dark, and the temperature range is much higher during the day and much lower at night than the Earth’s.

When the moon formed, it did not have enough gravity to hold onto an atmosphere. That means there is no air to breathe on the moon. There is also no weather. When Earth formed, an atmosphere developed around it. Earth’s atmosphere is made up of gases. We get the oxygen we need to breath from the atmosphere. Earth has weather because it has an atmosphere that includes air and water.

The distance around the moon (circumference) is almost 4 times smaller than Earth’s circumference.

Adapted from Connecting to Unifying Concepts through Space Science, 2006