August 29, 2003, 07:20 UT
Instrument: 10-inch Starfinder

Apparent diameter: 25".1
Phase: 100%
CM: 68°

Seeing is everything when it comes to planetary observing. No, I'm not using that term in the conventional sense: to observe or watch. I'm talking about the steadiness of the atmosphere. To borrow from Dick Suiter, it's useful to envision the view at the eyepiece of a telescope as perfect likeness which has passed through a stack of filters on its way to your eye. The light from a planet, such as Mars, must run a gauntlet of filters, each of which introduces aberrations into the final image formed in the eyepiece. The aperture of your telescope; the figure of the optics; secondary obstruction; tube currents...all of these conspire to degrade the final image. And where planetary observing is concerned the most harmful of these, is seeing.

When the atmosphere behaves like a puddle of water into which a toddler has just stomped his foot, not even the theoretically perfect telescope will produce decent images. But when the air calms, even mediocre optics can produce stunning views. This night, the seeing isn't perfect but it does calm for extended periods. And the calming is enough that I'm enjoying the best views of the red planet, this opposition.

At 388X with a 23A light red filter, Mars is presenting a wealth of delicate detail. Solis Lacus is just west of the central meridian. Its short, fat, lenticular form is unmistakable. Nectar's lengthy narrow form connects Solis Lacus with the large expanse of Mare Erythraeum to the east. Aurorae Sinus emerges north from Mare Erythraeum, terminating in a broad, ragged edge. Coprates (nea Agathodaemon) reaches west, a craggy finger pointing toward the CM. This albedo feature is actually the Solar System's largest canyon, Valles Marineris. Immediately to the north, Juventae Fons sticks out like a thumb at the northwest corner of Aonius Sinus.

The white South Polar Cap has abandoned its smooth oval outline and taken up a jagged uneven appearance. The following (west) side displays a large cleft and the preceding edge has been blunted by the irregular sublimation of the frozen carbon dioxide surface. The North Polar Hood glows faintly white along the opposite limb. More clouds edge the limb of the northwest quadrant. Aonius Sinus and Mare Sirenum reach toward and over the following limb. Araxes is visible, a slender prong directed to the northeast. And, finally, the dark forms of Niliacus Lacus and Nilokeras defiantly emerge through the Martian atmosphere. These northern features will not be well-placed for observing from Earth for two to four years.

August 30, 2003 August 25, 2003

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Revised: August 30, 2003 [WDF]