[meteorite-list] Vesta ready for First Gear again
From: MexicoDoug_at_aol.com <MexicoDoug_at_meteoritecentral.com>
Date: Sun Oct 17 17:22:22 2004
When one planet catches up, passes, and then continues happlessly on its tedious journey, how can we say when this planetary "passing" starts and when it is over?
Is it the time interval rounding off numbers creates defining the instant that we are at identical angles (opposition for those bodies with orbit radii greater than 1 AU).
I was pondering this trivial question last night that I wanted to share with the list, for no other reason that hopefully someone else out there relates. My conclusion is at the end of this message. This is meteorite related, as in the words of a deposed Iraqi, Vesta is "The Mother o'fall* Meteorites", as I while pondering this philosophical, and probably usless question, I was out for an encore of the Vesta Planetoid Show, with the typical instruments, eyeglasses, consumer binoculars, my nice Nikon, and digital camera that even Chicago Steve could trump if he reads his manual:
We were in the middle of a desert, the lone roadrunner we saw earlier was probably hiding along with the little unidentified hawk-fearing, scurring marsupials and big-eared desert hares, as the whistling wind and coyotes once again were howling to beat the band - the band of desert crickets and late evening chirping birds that is - Then there was the occasional WHOOOOOW! blasted from an errant cow that ripped through the silence by surprise, and then barreled over the barrel cacti to scare the ghost of Christmas past into the tarantula hideways peppering the desert pavement.
As sliver silver moon approached its setting, behind the mountains, it assumed a bright, crisp desert rose-copper color. We watched the last fingernail disappear leaving an impressive blackness dominated by the galaxial light of the Milky Way, and the faint dispersion of city light on the horizon in the less curious part of that night's sky.
I prepared the camera to photograph Vesta, in her encore Moonless performance since last month, though her magnitude was now a fainter 6.73 (twice as dim as the 6.08 in mid September) she was now harder to see in the opera glasses, but no problem in the cheap 16X binoculars, where she had fallen behind, right into the heart of Aquarius. All was set, and I was quite amused to discover that I left the camera's battery housing home. So now there was no excuse, and no strings attached (to the camera that is, to determine elevations), but to get huddled down together on our backs on a borrowed one-girl workout mat, from where we observed twelve different meteors extinguishing themselves through the course of the graceful early night, some apparently radiating from near the constellation Cygnus the Swan.
When Vesta reached her culmination at 10:21, I became somewhat thoughtful, and stealing some Chica-go advise, I played with the knob of the camera in manual mode and realized the lens opened up as wide as f/2.5 for 15 whole seconds! The tripod was useless, as the head fitting for the camera body was a slider and the digital camera needed a screw, I just tilted and propped the camera against a tripod leg with the self timer and prayed for the best. After several exposures of Vesta, I was sure to give a little attention to Uranus as well, who also should have been nearby on the ecliptic together there in Aquarius, and a I shot one including neighboring Capricornus for good measure on the odd chance that Neptune would crash the party.
The results were interesting and couldn't be judged on the LCD screen, so we put everything away and we contemplated the question of why Vesta was somewhat closer to Uranus than it had been since Springtime. That, as the astronomy buffs know is because of the "phenomenon" of apparent retrograde motion in relative orbits of objects. It is a geometrical result - when one speeds tangently and parallel at opposition, the faster (inner) body catches up, but the rest of the time the velocity of the inner turns in or out, and the outer body's parellel velocity component beats out the inner planet. We thought about Vesta in her three-year seven and a half month orbit and after a lot of idle contemplation decided that Earth had caught up to Vesta at the end of July when retrograde motion began, and we were now about to pass Vesta when retrograde motion was ceasing. That seemed reasonable enough for a more humanized definition of the planetary races - that passing was accomplished as Vesta was seen to recede and w
as finished when she started on her way again...which we now duly note is starting later this week once again. Just to be sure, we pantomimed the planets in the desert, and considered that it was a whole lot simplier concept than philosophically it seemed, and the coincidence that Vesta was now slipping out of sight only unofficially confirmed that fact.
The morning after (today), we are very pleased with the performance of the digital camera, as Uranus is unmistakable, and Vesta visible right at the detection limit ... but happily positively present!
I've posted the image (cropped at 100% resolution) of Earth's farewell to Vesta at this link:
Most of Aquarius is at the left with Vesta is barely visible (lower left hand yellow arrow) ad Uranus is quite visible, marked by the yellow arrow in the upper center (to the right of Vesta).
Happy Hunting and Clear Skies!
(asterisk indicates *literary license*, further confirmed in that Vesta has apparently struck once again on October 5, 2004 in Berthound Colorado on that special (non-Vestan) Monze Day, that Martians and Marcianphiles would love to claim for their own.)
Received on Sun 17 Oct 2004 05:22:14 PM PDT