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Jupiter at Opposition
StarDate:
April 7, 2017One of the brightest objects in the night sky is especially bright right now. That’s because Jupiter is at opposition — it’s lining up opposite the Sun. It’s closest to us now, and more of its light is reflected back in our direction, so it shines at its absolute best.
Jupiter is the largest planet in the solar system — about 11 times the diameter of Earth. And the clouds that top its atmosphere reflect a lot of sunlight. But even at its closest, it’s about 400 million miles away. That combination makes Jupiter the third-brightest object in the night sky — behind the Moon and the planet Venus.
It takes Jupiter more than 12 years to make one orbit around the Sun, which means it also takes it that long to complete one circuit against the background of stars. As a result, it spends an average of about a year in each constellation it crosses.
As Jupiter orbits the Sun, Earth is doing the same thing. Our orbit is much smaller, though, so it takes us much less time to make one turn around the Sun. It’s as if we’re on the inside lane of a race track, with Jupiter on the outside lane. It takes about 13 months for Earth to catch up to Jupiter and move past it, so that’s the gap between oppositions. In other words, the next opposition will be about 13 months from now — next May.
For now, look for Jupiter quite low in the east as night falls, and climbing across the south later on. It looks like a brilliant star.
