SJAA Ephemeris July 2006 | SJAA Home | Contents | Previous | Next

The Shallow Sky

See Spot. See Spot Merge?

Akkana Peck

Oval BA (Red Spot Jr.) is just above and to the right of the Great Red Spot. Photo courtesy of Christopher Go.


Remember Red Jr? Officially known as Oval BA, this smaller reddish cousin to Jupiter’s Great Red Spot (GRS) is still going strong in the South Temperate Band of the giant planet. It’s currently following the GRS by about an hour, but it’s catching up fast, and around July 7th (or possibly earlier) the two enormous storms will pass very close to each other.

Enormous? Well, Red Jr may seem like a small storm compared to the GRS, but think of a hurricane about the size of the whole Earth and you have Red Jr.

Red Jr is hard to see visually. I haven’t been able to see it with a 5” refractor, but I’ve heard reports of people spotting it with larger telescopes. To hunt for it, first train your telescope at Jupiter when the GRS is near or a bit past the meridian. You can find GRS predictors in most planetarium programs, in the tables in astronomy magazines, or on the web at or my own Java applet at

Once you’ve found the GRS, you know which direction is south (since the GRS is in the South Equatorial Band). The South Temperate Band is the next major band toward the pole. Use high power, as much as the sky permits: Red Jr. is fairly small and very subtle, so you want to magnify those small details as much as you can to have a chance of seeing it at all.

A photo may help to see exactly where it is in relation to the GRS. Red Jr has its own web site now: check with for recent photos and other information.

Around July 7th, the two spots will be very close together for a few days. It’s even possible that they could merge into one larger storm; but the experts say it isn’t going to happen. More likely, the larger storm might distort Red Jr as it passes by, as happened a few years ago back before it amazed everyone by changing color. (Might the color change have been caused by the interaction with the GRS? The color of these storms still isn’t well understood, so who knows?)

It’s a good thing Jupiter is so interesting this month, because there aren’t many other planets to observe! Mars and Saturn both disappear into the sun’s evening glow by mid-month, Venus is very low in the morning sky, and Mercury is too close to the sun to observe at all.

The outer planets are all accessible, though. Pluto transits just before midnight, so this month is perfect for a budding Plutocrat.Get yourself a good chart or planetarium program, a reasonably large telescope (start with 12” or bigger, at least if it’s your first time) and start comparing stars. When you think you’ve found Pluto, make a sketch (showing the stars you see in YOUR telescope, as opposed to the stars shown on the chart), then try again in a few hours, or the following night, to see if it’s moved.

Uranus and Neptune rise an hour or two before midnight and should be easy targets for late night owls. Uranus, in northern Ophiuchus, is fairly easy in a small scope as a small greenish disk; the small blue disk of Neptune, in Capricornus, is harder, but still within the reach of most amateur scopes.

The Earth reaches aphelion, its farthest point from the sun, on July 3. Aphelion is a great time for observing the third planet, especially its mountains and beaches. You probably won’t need a telescope for this, and you can do most of your observing in the daytime. But if you continue your observations into the early evening of the day after aphelion, you may see some interesting atmospheric phenomena that you won’t see on any of the other planets!


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