Skywatch: Jupiter has joined the evening sky

Have you seen this super bright star appearing in the low southeastern sky at dusk? That’s not a star, it’s the big guy in our solar system, the planet Jupiter. The 88,000-mile-wide planet, named after the king of gods in Roman mythology, is visible all night right now and is nearly closest to Earth for 2022. This week Jupiter is just over 372 million miles from Earth. The overall picture is that Earth and Jupiter are much closer than average in their respective orbits around the Sun.

In late September, Jupiter reached what astronomers call opposition when it was only about 367 million miles away. In fact, since 1951 it has been as close to Earth as it gets! It’s called opposition because Jupiter and the Sun are at opposite ends of the sky, just like a full moon. Earth is between the Sun and Jupiter as you can see in the diagram. Because they are at opposite ends of our skydome, Jupiter rises at sunset and sets at sunrise. The Jupiter giant roams the sky all night!

Earth and Jupiter come into opposition every 399 days, or about every 13 months. That’s because it takes Earth just over 365 days to complete one orbit of the Sun, while Jupiter takes 12 years to make its much larger solar orbit. In the one year that Earth orbits the Sun, Jupiter has traveled only a twelfth of the way around our home star. It takes Earth another month to “catch up” with Jupiter and realign with it and the Sun.

If you have super eagle eyes, Jupiter sometimes looks like it has tiny appendages on either side. These are moons of Jupiter. There’s no way to resolve them visually with the naked eye, but small binoculars or a telescope will show up to four of Jupiter’s brightest moons. They look like little stars on either side of the big planet. I’ll have much more on Jupiter’s moons and how to keep up with them in an upcoming Skywatch column.

Even with a small telescope you can easily see Jupiter’s moons, and you can also clearly resolve the planet’s disk and some of its cloud bands and zones brushing the Solar System’s big guy. Jupiter is mostly a large sphere of hydrogen and helium gas, but methane, ammonia, sulfur, and other gases create the multicolored bands of clouds in its outer atmosphere. The two darker cloud bands on either side of Jupiter’s equator are the easiest to spot.

Storms circulate in Jupiter’s upper atmosphere, with the largest storm being the Great Red Spot. It is three times the diameter of our earth. This huge, hurricane-force storm has raged on Jupiter for hundreds of years. Despite its nickname, the Great Red Spot isn’t quite as red, more like a pale pink. Unless you have a medium to large telescope and a super clear, transparent sky, it’s hard to spot. What also makes it difficult to see is that it is not always visible due to Jupiter’s rapid rotation. Jupiter spins around its own axis in less than ten hours. Half the time the Red Spot is pointing away from our direction.

A really handy app to see if the Red Spot is pointing our way is simply called Jupiter’s Moons.

When viewing Jupiter through a telescope, the key word is patience. Above all, wait until Jupiter is high enough above the horizon that you don’t have to see through as much of Earth’s fuzzy atmosphere to see it. Jupiter should be high enough for a decent telescope view around 9:00 p.m. Also, it is good practice to make long and continuous observations through the eyepiece whenever you have your telescope on one of the planets. Not only does this give your eyes a chance to adjust to the intensity of light in the eyepiece, but you also have a better chance of catching calm, less turbulent patches of clearer air drifting by in Earth’s atmosphere.

Get used to seeing the king of the planets in our night sky, as it will be visible in the evenings well into next year.

Heavenly event this week: Shortly after 9 p.m. on Friday evening, October 14, the waning crescent moon will be in the upper left of Mars.

Even to the naked eye, Mars will have a reddish cast. By Friday night, Mars will be 65 million miles away but getting closer and closer to Earth.

UPCOMING STARWATCH PROGRAMS

• Wednesday, October 12, 7-9 p.m., Metro State University, St. Paul campus. For more information, call 651-793-1300 or visit www.metrostate.edu.
• Thursday, October 13, 7-9pm, at Dakota Parks Whitetail Woods Regional Park, Farmington. For more information and reservations, call 651-437-3191 or visit www.co.dakota.mn.us/parks/Pages/default.aspx.
• Friday, October 14, 7-9 p.m., at Fort Folle Park By Siren, Wis., Community Ed. For location and other information, call 715-349-7070 or visit cueclass.com.
• Saturday 15 October, 7-9pm, New Brighton, Highview School. For more information and reservations, call 651-621-0020 or visit www.moundsviewschools.org/communityeducation.

Mike Lynch is a retired amateur astronomer and broadcast meteorologist for WCCO Radio in Minneapolis/St. Paul. He is the author of Stars: a Month by Month Tour of the Constellations, published by Adventure Publications and available in bookstores and at adventurepublications.net. Mike is available for private star parties. You can contact him at [email protected].