Our space

This infrared view of Jupiter’s icy moon Ganymede was obtained by the Jovian Infrared Auroral Mapper (JIRAM) instrument aboard NASA’s Juno spacecraft during its July 20, 2021 flyby.

If you were out after sunset last week and looked up at the southern sky you will have noticed a ridiculously bright “star”. Congratulations — you just spotted the planet Jupiter! The beautiful full Moon was right there as well, and a little further to the right the planet Saturn was also very easy to see. You can still catch them tonight — just look up towards the south and find the brightest object in the sky, and the bright dot about a fist-width to its right.

Both planets are in opposition this month. This means that they and the Earth are all on the same side of the sun, roughly lined up, so we see the full reflection of the sun’s light off their cloudy atmospheres. It’s an amazing sight for sure.

If you have access to a small telescope or even a good pair of binoculars you might be able to see Jupiter’s four largest moons, Ganymede, Callisto, Europa and Io. Galileo Galilei was the first one to spot these moons and thus they are often referred to as the Galilean moons. Jupiter has over 79 moons, not all of which have names yet, and more are discovered on a fairly regular basis.

Lucky for us we have a front row seat to Jupiter’s beauty right now! If you’ve been reading Our Space for a while you will be familiar with the Juno mission, which launched 10 years ago and arrived on July 4, 2016. Juno is the farthest spacecraft from the sun that uses solar panels, and because of this vast distance they have to be huge to collect every tiny bit of sunlight to generate the electricity needed to run the spacecraft’s instruments.

Juno is the first spacecraft ever to get a good view of Jupiter’s poles. Up until then we were only able to see the giant planet from its side. Juno showed us the amazingly marbled polar regions, full of smaller stormy vortices (smaller being a relative term, as one of them can easily be the size of Earth), and stunning colors and textures.

Jupiter’s moons make for fascinating science objects as well. Europa will soon have its own exploration mission with the Europa Clipper, and Io is one of the most volcanically active places in the solar system. Callisto has an amazing amount of craters and Ganymede is incredibly large. All those moons are worlds unto themselves worthy of individual exploration.

Juno has a big fan club among astro-photographers and photo-manipulators. Every single raw image taken by the spacecraft’s JunoCam is uploaded online and becomes available for those who want to fiddle with the images, enhance the color, overlap partial photos and generate some of the most beautiful images of the planet we’ve ever seen.

For the 10th launch anniversary the mission science team has released a new image of Jupiter’s huge moon Ganymede which was generated over the course of three flybys, using an infrared camera that wasn’t even intended for this purpose. The JIRAM camera (short for Jovian Infrared Auroral Mapper) is there to map the infrared light or heat signatures emanating from Jupiter’s interior about 40 miles beyond the dense visible cloud layer, but as it turned out it was incredibly useful to explore Ganymede’s surface as well. Ganymede is actually larger than the planet Mercury, but then again, everything about Jupiter is super-sized!

So how big is Jupiter? It’s hard to imagine. Jupiter is big enough for all the other planets to fit inside of it. You’d need over 1300 Earths to fill up its volume! But it’s still too small to collapse into itself and become a star. Fun fact: Jupiter has rings, similar to Saturn, but they are far less spectacular and only visible upon closer inspection. The Voyager 1 spacecraft discovered the rings on its flyby in 1979, and the Galileo spacecraft explored them more thoroughly in the 1990s.

Jupiter also sports one of the longest-living storms in the solar system: the infamous Great Red Spot is a hurricane that has raged for well over 350 years. Let’s just be glad that most Earth hurricanes only last weeks! And despite its enormous size Jupiter is the fastest-rotating planet in our neighborhood, completing one full rotation in less than 10 hours, so a turbulent atmosphere and big storms are pretty much inevitable.

Explore the Juno mission website at https://www.missionjuno.swri.edu/ where you can find the latest news, a mission timeline, gorgeous videos and all the photos your heart can handle.

Beate Czogalla is the Professor of Theater Design in the Department of Theatre and Dance at Georgia College & State University. She has had a lifelong interest in space exploration and has been a Solar System Ambassador for the Jet Propulsion Laboratory/ NASA for many years. She can be reached at our_space2@yahoo.com .  

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