The Great Red Spot Spotted!!

by Kevin Mooney

After the little kiddies go home on a public night, there’s always one object you would like to go back to view again later in the evening. That moment came on Friday June 9th when Team 2 spotted the “Great Red Spot” on Jupiter, which was perfectly-positioned front and center on the planet’s surface. That is to say it was front and center from our vantage point. In the telescope that evening, you’d have to look below the two most prominent gas bands to see the unmistakable, oval bulge that is the Red Spot, which is located slightly south of the planet’s equator. While there wasn’t any actual red, or any color for that matter that I could discern, the longer you stare, the more details you can flush out.

We had a lot of Boy Scouts that night and other interested members of the public. There was also a lot of competition for the Red Spot among astronomical objects within view on what turned out to maybe the best Friday night of the year so far. Some of the other objects we saw that night were globular clusters – M5 and M13. Since Ursa Major sits in an ideal part of the sky, we also took time to view M81 and M82 (Is M82 slightly brighter?). There was also some of my favorite doubles: Cor Caroli, Albireo, Mizar, and the Double-Double. By time we turned the telescope back to Jupiter it was after 10:30 p.m. and the Red Spot was gone! That’s partly my fault because I was complaining about how the Phillies lose every time I go to a game. But it was pointed out to me that they also lose when I don’t go to the games. So, I should have just got on with it.

So how fast does the Red Spot actually move across the surface and what are we actually looking at? Apparently, it takes almost a week (Earth week) for the Red Spot to completely rotate around the planet. Most of the club members I have spoken with say they typically get an “edge-on” view of the Red Spot. So we were fortunate to get the whole storm.

In a nutshell, The Red Shot is a gigantic storm that has been swirling across Jupiter for hundreds of years. We really don’t know how long it has been in motion. While it was first recorded in 1831, according to, it was probably first observed much sooner.

Think of it as a giant cyclone with wind forces of more than 400 mph stretching at about 12,400 miles (or 20,000 kilometers) long and about 7,500 miles (or 12,000 kilometers) wide. So doing the math, the Red Spot could swallow up three Earths. Or, at least, it used to be that size. The storm has been shrinking somewhat in recent years. Now it’s more like the size two Earths.

If you really want a good look at the true size and scope of the Great Red Spot as it appears today, take a look at the photos NASA’s June spacecraft snapped just a few weeks ago. Juno dropped in less than 6,000 miles from the Red Spot’s cloud tops, which is closer than any spacecraft has ever gotten. Astronomers who have closely examined the Red Spot over the years have gathered evidence that suggests it has been continuously feed by other storms, which would explain in part why it has persisted for so long. But how much longer will it go?

We could be witnessing the beginning of the end. Hubble Space Telescope images show the Red Spot has been shrinking at an accelerated pace in recent years. So, get a good look now! We did.

This entry was posted in Mid-summer 2017, Sidereal Times and tagged , , . Bookmark the permalink.

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