All the planets in the Solar System move around the Sun roughly along the same plane. That means that if the Sun was in the middle of a huge piece of paper, all the planets would go around it, along the same piece of paper. Often they do move slightly above or slightly below. It's this movement up and down that means an event that took place on Tuesday 8 June, 2004 has not happened since 1881. 
Venus can be seen clearly as it begins its journey |
Not a single person alive had seen it before! On Tuesday 8 June, 2004 starting at 6.19am, the planet Venus began to pass directly in front of the Sun. It took about six hours to get all the way across so everyone had until 12.23pm to have a look at it through special telescopes. So what was happening? Well it's really simple. Venus passed directly between us and the Sun, allowing us to see it as a silhouette against the brighter Sun's disk. Seeing these Transits of Venus, as they are properly called, have been of great importance in earlier times. They have allowed us to get a very good understanding of the path of it around the Sun and also of the distance to the Sun and the rest of the objects in the Solar System. Astronomers were sent all around the world on long sea voyagers to watch these events - even Captain Cook got involved when he went to Tahiti in 1769. If you missed this one, don't worry - these things come in twos and the next will be in June 2012. But if you miss that one you will have to wait another 105 years until 2117! Venus facts  |  | Venus is the second planet from the Sun | | | | Venus is the hottest planet in the Solar System temperature at its surface about 500 degrees | | | | At Venus' surface, it rains sulphuric acid! | | | | Venus is often seen in the early evening or early morning sky, looking like a really bright star | | | | Venus is often thought to be a UFO | | | | It takes Venus 243 days to spin once on its axis and 225 days to go around the Sun. |
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