SJAA Ephemeris March 2002 | SJAA Home | Contents | Previous | Next



Dave North


There just isn't any better zone than Copernicus.



What does a month with the Moon look like? How do "seasoned observers" approach - and react - to observing?

I thought it might be useful to just publish my log for January; it might give you some ideas. March, by the way, is one of the best mooning months. You should be able to do better than this.

1/18/02 Tak FS128 7mm Nagler (145x)

Set up about 5:45 to try to get the early evening seeing. Moon well past the meridian at sunset, but still pretty high.

Everything's a little disorienting with Crisium librated so strongly toward the limb - amazingly confusing, really. At one point I spotted the southern end of the Altai Scarp and couldn't figure out what it was... of course, it was extraordinarily bright, too.

Seeing fair, but not great.

Poseidonius smack on the terminator; part of it still obscured in shadow but what does show is hot - great contrast.

Nearby Rima G.Bond is obvious in the Tak. It's a long rille, and conditions are particularly good tonight. You can see pretty much the whole thing. Its southern section is called Rima Romer, but I'm convinced they are both just one long fracture.

Even at a glance, there's a slightly less pronounced "straight wall" fault in Serenitatis. I don't recall noting this before.

Akkana spotted an interesting rift or rise near Torricelli: another one of those things that shows up well in light that's "just so." My guess is it's one of the Imbrium splatters.

Still a good view of the cracks in Janssen, though it's probably over a day old. Excellent light overall.

1/19/02 Tak FS128 6mm Vixen Lanthanum (170x)

Seeing not so hot tonight. Got my first observations starting 5:45 again. Probably the next few nights will deteriorate, but c'est la vie. The best thing to do under such circumstances is appreciate the lower power view and get into the aesthetic, then watch a movie or something.

So, of course, I went rille hunting instead. More of a challenge.

I love the name Lacus Mortis, and it's easy to find: Atlas and Hercules point directly to it and Burg is a distinguished crater in its own right.

I hunt rilles, and Rima Burg is easy, so it was a natural for a feeble night. It showed surprisingly well, but by now I should not be too surprised by this effect: poor seeing can still allow fine views, in "phases." If the seeing "waves" are slow, there will be solid periods of some fraction of a second when the "wave" moves through the focal zone. Result? If you're patient, you can see pretty much everything, but it can be frustrating.

Pretty fair view of the main Rima Plinius extending from the end of Promontorium Archerusia (the names we loonies get to type...) Some hints of the secondary rilles also. This is not normal for iffy seeing.

Nice view of the region of Hypatia and the rille of the same name ... but the lighting effects on the Imbrium Globs were actually more striking than the rille.

Such nice light also allows a chance to soak in the "tonality" of the moon ... the play of lighter and darker grays, the sharp whites where sunlight reflection is practically direct, the smooth shadings on the maria.

I'm not usually as captivated by the near darkside lights as some folks, but tonight they were exceptional. (Okay, this is when peaks or crater rims that are higher than the "datum" are lit, just barely on the darkside of the terminator, while the flatter land around them is still in shadow. They seem to "hang in space" and can be quite striking. Often - as tonight - there is a tiny point off a horn that is a peak right on the limb. Exquisite).

1/20/02 Tak FS128 7mm Nagler (145x)

Late start after making the hike up Mission Peak. Perfect day, except everyone else realized the same thing and it was pretty crowded on the "Hilary Step."

Great Hyginus and Triesnecker rilles tonight. Really, nothing more need be said for the seasoned observer: the best.

Hyginus is a "broken" rille (looks like a drawing compass spread way wide with a small crater at the 'hinge'). The interior of the eastern arm has a bunch of sump 'craterlets,' a few of which were visible.

Almost all of Triesnecker (perhaps the most glorious rilles on the Moon) could be seen. They're a crosshatched pastiche of very fine lines, complex enough to get lost in.

Nights like this are what mooning is all about.

1/21/02 Clouded out.

1/22/02 Tak FS128 7mm Nagler (145x)

Started during twilight (about 5:15 p.m.) for a change. Sky was somewhat cloudy but transparent enough. Seeing sorta ho-hum, which is good considering.

Copernicus night. This is variation two, where half the Copernicus area (with the secondaries) shows up one night, and the other half (with the domes) the next. I wonder if I'll see the other half.

Variations One and Two alternate each month.

There just isn't any better zone than Copernicus. Rilles, secondaries, mountains, well-defined crater, domes, rays, basaltic flows: everything.

Just to be nasty, the Hesiodus sunrise ray made an appearance, right next to the magnificent Rima Hesiodus.

Plato comes into view this night.

Tons of radial rilles around Mare Imbrium in the Archimedes area (Hadley/Bradley/Conon et al).

This is the richest observation night of the lunation, period. Describing everything available is simply impossible. And it's high in the sky this time of year.

'Nuff said.

1/23/02 Tak FS128 7mm Nagler (145x)

Great night! The classic showoff Sinus Iridum hanging off the edge into the dark side ... seeing it you get a feel for how right Floyd was with their music.

The seeing was extremely good for winter, so the major rilles were very showy: rimae Ramsden (rilleville) and Hippalus especially. (Hippalus is extremely cool in that it looks like some huge raptor ripped its claws across the opening of Mare Humorum. If you haven't seen this, it's every bit as dramatic and surprising as it sounds).

Platolets (small craters in Plato) showing even at that mag (this is often seen as a test of seeing).

It was also a particularly good night for the Riphaeus Mountains, a favorite of mine. They're a construction of several interlocking craters that were drowned by a later basaltic flow. There are several examples of such, but none quite so rich.

1/24/02 4.5-inch Newt 7mm Nagler (130x)

Iffy seeing and a bit of haze and cloudiness, but not bad. Good enough to pick out the rilles around Mare Humorum and see the fractured floor of Gassendi (great!) pretty well.

Light angles were such that the area around Prinz (a sunken crater near Aristarchus) was very distinct. The striking thing was how rounded were the Montes Harbinger (montes = mountains). Rukl shows them as "peaked" or "sharp" in his drawings, but at a glance they could easily be mistaken for domes in the same class as the nearby Gruithuisen twins (two similar peaks near Mairan that have elusive peak craters - they're something like shield volcanos apparently).

Domes, by the way, are more or less volcanos.

The terminatorward edge of Aristarchus was just barely lit, which is a spectacle unto itself: an amazingly bright thin crescent. Aristarchus is (I think) the brightest significant spot on the Moon - certainly one of the brightest. One speculates the crust underlying the skin where it formed is particularly light in color, and was exposed by the impact.

It's a weird crater in a number of ways. It sits on a plateau completely surrounded by basaltic flows from Oceanus Procellarum, the largest contiguous zone of mare material. It also has an incredible sinuous rille, Schroter's Valley, running downhill from it. This was almost certainly the Mother Of All Lava Tubes, collapsed and exposed.

I don't know if there's anything of that scale on earth, but the little ones I've seen have been magnificent.

1/25/02 Binos 8x

Mostly clouded out, but mildly interesting through the binos. Starting to take on that "full" characteristic.

1/26/02 Nothing

Rainy, cloudy, had a party to attend. Zip, except lights through the clouds

1/27/02 4.5-inch Newt 7mm Nagler (130x)

Got a good look at Mare Orientale while it was librated about 4.5 degrees toward us, with an increasingly ideal terminator position - except for one thing: it clouded out before the Moon got really high or the best presentation happened.

Very argh. But that's life.

1/28/02 Nothing

Clouded out after a rainy morning. Some hope for tomorrow, but we're after full now... well, not completely a loss. At one point, behind thin clouds, it had a diffraction halo that was stunning. Like a mini-rainbow all around it!

1/29/02 Cold

It was just too cold later, and I couldn't bring myself to set up. A cursory binocular glance showed very little terminator.

1/30/02 12.5-inch Newt 7mm Nagler (220x)

Seeing seemed okay so I set up primarily to be able to pump up on Saturn, which paid off nicely. It's newt-friendly (high contrast in the rings). Nice all-round view of the EnKeeler Gap. Plotted the moons against Ak's SatMoon program for PalmOS, and it did pretty well.

1/31/02 Binos (8x)

Nice terminator position, but it was low over the roof, really boiling. And that was pretty much it for this month.

Fairly typical for winter.

See how easy it is?


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