Mars OR, 8/14/2005

by Marek Cichanski

Saturday was a Lick Observatory visitor program, and I was one of the 'outdoor' volunteers. After the public had looked through our scopes and through Lick's big glass, it was the wee hours of Sunday morning, and Mars was getting reasonably high in the sky. Jeff Crilly, Rich Neuschaefer, and I had some nice views of the Red Planet. Rich was using his 7" (f/9?) AP refractor, and I was using my 18" f/4.5 Obsession. On my scope, I used a TeleVue ParaCorr, a cheap Meade 2x shorty barlow, and a 7mm type 6 Nagler, for a magnification of 673x.

Until Saturday night / Sunday morning, every view of Mars that I've had this year has been pretty watery. I've been able to see the polar cap, and have been able to tell that there are some dark markings, but that's it. The other night at Lick, however, the seeing got quite good. We had a nice view of the south polar cap, and we had a reasonably clear view of the dark markings. The polar cap was fairly small, but bright and well-defined. It seemed as though there was some whitish color around the north pole. We wondered if perhaps there was some cloud and/or frost in the north polar region.

The dark markings on the planet's disc seemed to me to be in the form of an 'equatorial band'. North and south of this band, the planet showed its 'baseline' color of light orangish salmon pink. (Yes, that's how it looks to me.) The southern edge of the 'band' looked to me like a fairly well-defined line that ran along a parallel of latitude. The northern edge of the band was more complex. It seemed to me that it had two dark northward projections that stood out more prominently than the rest of the north edge. This didn't look to me like the distinctive 'pipe-shaped' dark region that is Sinus Sabaeus and Sinus Meridiani. Rather, it reminded me of the big, north-projecting 'block' of Mare Erythraeum.

Mars had two limbs - the normal limb of the planet as seen against the background of space (this was the eastern limb, celestial convention), and the 'terminator' limb. Mars is showing a gibbous phase right now as it slowly approaches opposition. The 'gibbous' limb is the sunset terminator. I thought that the area south of the 'dark equatorial band' looked a little brighter near the 'normal limb'. I wondered if this was one of the big impact basins, such as Hellas or Argyre. Hellas didn't make a lot of sense, because it's south of Syrtis Major, and we didn't seem to be seeing Syrtis.

So, I downloaded Mars Previewer II from the S&T website, and checked out what Mars 'really' looked like. The result was weird. Turns out that Sinus Sabaeus / Meridiani really WAS visible, although I sure didn't see it. I didn't see any of Decaulionis Regio, the light area south of the 'pipe'. Strange. I think that I did see the light area between Sinus Meridiani and Mare Erythraeum, and my 'Hellas Basin' may have been Argyre. Other than that, though, I didn't see much of what was 'supposed' to be there.

Just goes to show how tricky Mars is. Ain't nothing easy about it. I'd kill to see some sign of Olympus Mons, even just in the form of a cloud, but I'm sure not gonna hold my breath.

Now that we're able to see stuff on Mars again, at least on nights of good seeing, I'll give another plug for William Sheehan's book on the history of observing Mars, which is available to read for free online. I'm sure I've posted links to it before, but I thought I'd give it a shout-out again. Makes a nice read during a bright moon cycle:

http://www.uapress.arizona.edu/onlinebks/mars/contents.htm

Posted on sf-bay-tac Aug 15, 2005 13:04:54 PT
Converted by report.pm 1.2 Mar 07, 2006 20:05:23 PT