a region in space where gravity is so strong that nothing, not even light, can escape - a black hole, an occasion when a number of meteors move fast across the sky at night - a meteor shower, a large heavenly body revolving about a star other than the sun - a planet, an occasion when the sun disappears from view, either completely or partly, while the moon is moving between it and the earth, or when the moon becomes darker while the shadow of the earth moves over it - an eclipse, the moon when it is shaped like a complete disc, or a time when it is - a full moon, the distance that light travels in one year (about 9.5 million million kilometres) - a light year, a vehicle in which people can travel round the earth, outside its atmosphere, doing scientific tests - a space station, a star having a diameter of from 10 to 100 times that of the sun, as Arcturus - a giant star,

RO4 3a: Did you know?

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