Space race
Why are transits of Venus so rare?
Venus's year is shorter than Earth's, lasting 224.7 days. Like a speedy Formula 1 racer, it manages to 'lap' the Earth. Every 584 days Venus lies between us and the Sun - this is called an inferior conjunction.
But the orbits of Earth and Venus are at angles to each other. So most of the time when Venus is between us and the Sun it's above or below the plane of our orbit, and seems to pass above or below the Sun. This means we don't see a transit.
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