SJAA Ephemeris March 2012 | SJAA Home | Contents | Previous | Next

The Shallow Sky

Serpent Storm

Akkana Peck


March brings us a wealth of interesting planets to look at.

Mercury hangs low in the dusk sky, while above it, Jupiter passes Venus on its dive toward the sun. Our two brightest planets pass closest around the middle of the month, within a few degrees. Uranus is there too, but it’s below Mercury, so it’ll be a tough target in the twilight glow.

Once the twilight opening act has ended, it’s time for the real stars– ahem, planets – of March evenings: Mars and Saturn.

Saturn first. It’s a late-evening object: it doesn’t rise until 9:30 at the beginning of March, an hour earlier by month’s end, so it really isn’t very high until midnight.

But it’s worth taking a look, especially on a night of good seeing. There’s a huge storm raging in Saturn’s northern hemisphere. It shows up as an extended white area of turbulence – like the area following Jupiter’s great red spot, but showing white against Saturn’s usual creamy yellow-brown color. It’s so long that some are calling it “The Serpent Storm”.

The storm has been around for months, but it gets a lot more convenient to observe this month as it moves into the evening sky. Some images show lots of swirling, turbulent shapes; others show just a white band. Either way, it’s more detail than we usually see on Saturn’s surface, and it won’t be there forever, so take a look and see if you can find it and watch it change.

Mars hits opposition on March 3, so it’s now officially Mars Observing Season. Its closest approach to Earth happens two days later, on the 5th.

(These don’t happen at the same time due to the eccentricity of both planets’ orbits.)

Sadly, this will be the most distant opposition since 1996, with Mars showing a small disk not quite 14 arcseconds across. But the compensation is that it’s high in the sky, so in those nights of steady air, you’ll still be able to see a surprising amount.

Mars’ northern hemisphere is tilted toward us, though only by about 20 degrees. That hemisphere is just entering summer, with the solstice on March 30.

Around opposition, Sinus Sabaeus and Sinus Meridiani will be showing on the south-central part of the disk around 10pm to midnight, with the Tharsis plateau more centrally placed, and Mare Acidalium rotating in to the east.

By the weekend of the 10th, Syrtis Major will dominate the south. That means the south limb of the disk will be taken up by Hellas, an impact crater that usually shows up so bright that it’s easy to mistake for a polar cap. If you think you see a polar cap, bump your scope a little towards north or south and watch which way the view moves. If the “polar cap” you see is on the south side, it’s Hellas. The real polar cap is in the north, and it’s much smaller than Hellas and probably not very bright since it’s nearly summer there.

On the following weekend, the 17th, not many features are visible, but you can still look for that elusive north polar cap, ringed by Mare Boreum. In the south, Mare Cimmerium comes in from the east. Around the center of the disk, try for a faint feature that sports one of my favorite Martian feature names: Trivium Charontis.

The weekend of the 24th presents an even blander view. Centered on the disk is Olympus Mons – a fabulous volcano, but alas not easy to see from Earth. Sometimes you can see evidence of it as lighter, almost bluish patches: clouds formed by winds blowing up the mountain’s slopes. You can see a bit of Mare Sirenum in the southwest, and a bit of Mare Boreum in the northeast.

Happily, by the end of the month, features are rotating back in – Acidalium and Chryse in the north, Solis Lacus in the south.

In all this talk about Saturn and Mars I didn’t mention Neptune and Pluto. They’re both morning objects in March: catchable if you’re really dedicated, but the rest of us will probably want to wait a few more months. But considering how much there is to see this month, that shouldn’t be a problem! Just don’t forget about Daylight Savings Time, which begins on March 11.


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