|August 30, 2003, 06:40 UT|
Instrument: 10-inch Starfinder
Tonight, Mars is 0.04 arcsecond smaller in angular size than he was at opposition. I round to the nearest tenth of an arcsecond in my notes so, that almost negligible change translates to a difference of 0.1 arcsecond in my reports. Although the best part of this year's apparition has passed, Mars still looms large and bright in the midnight sky. And when the seeing cooperates, as it did tonight, the views are spectacular.
Margaritifer Sinus is centered on the disk. At 388X, its scalloped northern edge sharpens dramatically when the air steadies. To the east along the preceding limb, the fanged profile of Sinus Meridiani is rotating off the disk. The narrow appendage reaching over the horizon is Sinus Sabaeus.
Moving toward the following side, Mare Erythraeum smoothly transitions into Aurorae Sinus. Juventae Fons protrudes like a stubby toe from the northwest corner. Just to the south, Coprates' gnarled form reaches westward. This feature corresponds to the largest known canyon in the Solar System, magnificent Valles Marineris. The large oval form of Solis Lacus stands out to the southwest. Aurorae Sinus, Mare Erythraeum, Protei Regio, Bosporos Gemmatus, Aonius Sinus and Mare Sirenum meld into one dusky arch around Solis Lacus. Slender dagger-like Araxes' points toward Solis Lacus from Mare Sirenum.
During extended moments of good seeing, the large oval form of Pyrrhae Regio pops into view. The smaller oval to the southwest is Argyre I, another of the large impact craters visible on Mars. The South Polar Cap presents a distinct, irregular outline. While along the opposite limb, the North Polar Hood cloaks Mare Acidalium. Niliacus Lacus is quite subtle immediately to the south. Following this feature, the mottled jumble of Nilokeras and Idacus Fons emerges to the eye. An 80A light blue filter brings out clouds along the north and west limb of the planet.
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Revised: September 8, 2003 [WDF]