55 people. What can you do when there is high haze, a bright Moon and too much sky shine? What else, look at bright objects. Mars and the Moon took center stage all night long. The haze has a curious effect, it often produces extremely stable astronomical images. Tonight was such a case. I have only rarely seen the limb of the Moon as fre of turbulent waves as this evening. I have to admit that I hadn't done my homework before showing up and I initially misidentified dark areas on Mars (I thought it was Syrtis Major) and a mountain chain on the Moon (I though it was the Apenines).

Here is a sketch of what my impressions were of Mars Friday evening:

In fact the mountain chain which ringed a the lunar sea was the Haemus Mountains which form the central border of Mare Serenitas. Each mountain stood out clearly. At the end of the curved line of mountains the crater Plinius was clearly deliniated. The walls were crisp and the central ejecta mass was prominent. Ejecta masses form when an asteroid or a comet strikes rock. Momentarily the rock is heated to magma. The depressed area when the object hit the surface is submerged in the molten stone for a few moments before it squirts out under huge pressure forming a rugged hill or minor mountain.

The area I mistook for Syrtis Major was the slightly darker region including Mare Erythium and Lacus Solis. The Tharis region (a large plain) appeared to the left and slightly above the dark region. Many people expect a sharply deliniated set of features ala the Moon's craters, but Mars has a weather of sorts with great sand storms which abrade and coat the crater walls and mountains on Mars. Instead of a sharp dark shadow, areas tend to have shades of orangy-brown from peach to brick. No single color has high contrast except the polar regions at the northern or southern rims.

-Les Coleman

Author:

Leslie Coleman

Entry Date:

Jun 29, 2001

Published Under:

Leslie Coleman's Log