Mars had an oxygen-rich atmosphere around 4 billion years ago
13
If you went out into space, you would explode before you suffocated because there's no air pressure.
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More than 20 million meteoroids enter Earth's atmosphere every day.
139
The Sun and Moon appear to be the same size because the moon is 400 times smaller than the Sun, but 400 times closer to Earth.
13
Scientists have confirmed that Enceladus, one of Saturn’s moons, has a watery ocean.
6
The Earth gets heavier each day by tons, as meteoric dust settles on it.
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