A deep crater (4.85 kilometers) and youthful by lunar standards (roughly 100 million years old), Tycho (Figure 10.12) is another spectacular feature that dominates its surroundings. However, this 85-kilometer crater is sited in the rugged southern uplands where it can almost be lost at very low Sun angles when shadows of mountains and craters confuse the scene. In fact, Tycho is one of the few craters that dominate at full Moon. Under these conditions, with no shadows, the Moon is a rather bland and dazzling feature. However, Tycho's spectacular ray system dominates much of the southern hemisphere at full Moon and the crater itself becomes a glowing white ring, with a dark halo and a bright center. Of course, Tycho's rays
are this prominent because it is such a relatively new impact crater and other smaller impacts, from asteroids, meteoroids, and micrometeoroids, have not eroded the rays. Many astro novices, when they see the full Moon through a telescope, assume that Tycho marks the lunar south pole as, subconsciously, that ray center looks like it must have a geographical significance. In fact, Tycho is only at 43 degrees south; that is a full 47 degrees north of the lunar south pole.
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