Formation of the Earth and It's Early History

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In general, planets that have a greater number of craters on their surface are:

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older.

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Terrestrial planets are usually:

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closer to their star than gas giants.

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One major difference between the Earth and the Moon is:

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The Moon does not have plate tectonics.

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As you move further away from the center of the solar system, the planets get less dense.

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the planets get less dense.

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Scientists are able to determine how the Earth formed by:

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radioactive dating of meteorites, analyzing craters on the Earth and Moon, studying the size and composition of other planets.

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Earth does not have nearly as many craters as the Moon because:

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many of the Earth's craters have eroded away.

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The amount of time it takes for 50% of a sample of a radioactive element to decay is called its:

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half-life.

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When an unstable element like uranium turns into a more stable element like thorium, it is called:

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radioactive decay.

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Erosion: Options: can be caused by wind, water, or aliens., only occurs on planets that have an atmosphere., may cause planets to have more craters., all of the above.

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only occurs on planets that have an atmosphere.

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Based on current scientific evidence, how old is the Earth?

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4.6 billion years old