Jupiter Shines Extra Bright

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 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. Click above for a larger image.

S&T: Sean Walker

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. See SkyandTelescope.com/jupiteralmanac to find out when these events will happen. Or use one of our Interactive Observing Tools.
Uranus Too
Coincidentally, Jupiter is also passing almost in front of the planet Uranus just now. Uranus is 5 times farther away and almost 3,000 times dimmer, so it’s invisible to the unaided eye and contributes no light to speak of. But binoculars or a telescope will show Uranus less than 1° from Jupiter now through September 24th. At magnitude 5.7, Uranus is the brightest "star" that's that distance roughly north of Jupiter, and you may be able to recognize it by its bluish color (The authors of this article differ on the hue — Alan MacRobert considers it to be very subtle, while Tony Flanders finds it distinctive and unmistakable.).A telescope at 150× should show Uranus's tiny disk.
See SkyandTelescope.com/uranus for more information on observing Uranus, complete with a detailed finder chart.

Sky & Telescope illustration

On the other end of the brightness scale, the full Moon joins this celestial scene around the same dates too — shining above Jupiter on the evening of September 22nd and left of it on the 23rd, as shown in the illustration at right. More coincidences are also happening here. Jupiter and Uranus find themselves close to the point on the sky known as the vernal equinox, where the Sun crosses the celestial equator on the first day of spring. (“Spring” here means spring in the Northern Hemisphere.)
And, all of this takes place around the date when fall begins in the Northern Hemisphere: on September 22nd. (Fall begins at 11:09 p.m. Eastern Daylight Time on that date.)
What do all these coincidences mean? Nothing at all. Lots of things are going on in the sky all the time. Any particular arrangement might not happen again for centuries, but as the saying goes, there’s always something. Enjoy the show!

Post courtesy of www.skyandtelescope.com