If you look up on any clear September night, a big bright “star” will greet you. It’s low in the east after twilight, and higher in the southeast as the evening grows late. This is the planet Jupiter, and it's far brighter than any true star in the night sky.
Jupiter is always bright, but if you think it looks a little brighter than usual this month, you’re right. Jupiter is making its closest pass by Earth for the year. And this year’s pass is a little closer than any other between 1963 and 2022.
Jupiter is nearest to Earth on the night of Monday, September 20th: 368 million miles away. But it remains nearly this close and bright (magnitude -2.9) throughout the second half of September.
At the closest point of its previous swing-by, in August 2009, Jupiter was about 2% farther from both Earth and Sun than this time. That made it 8% dimmer. At its next pass, in October 2011, it will be 0.4% more distant than now.
Jupiter on Sepetember 2, 2010
Jupiter on September 2nd, shown with south up, as it appears in a reflecting telescope. The Great Red Spot is prominent at upper left, and the South Equatorial Belt is almost invisible.
Also, according to legendary planetary observer Richard Schmude, Jupiter is an additional 4% or so brighter than usual because one of its brown cloud belts has gone missing. For nearly a year the giant planet's South Equatorial Belt, usually plain to see in a small telescope, has been hidden under a layer of bright white ammonia clouds.
Because Jupiter is so close to Earth, this is a great opportunity to view it through a telescope. Jupiter is most interesting when the Gred Red Spot is visible and/or when one of the moons is casting a shadow on Jupiter's disk.
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