ASTA01H3 Chapter : Mercury/Moon
Document Summary
I ntro to astronomy and astrology part i. never strays far from the sun: only visible just before dawn or just after sunset. by measuring the spread of frequencies from either side of the original wave length we can determine the planet"s rotational speed. mercury"s rotational period is 59 days: exactly two-thirds of the planet"s orbital period. unlike the earth-moon relationship the moon being tidally locked with the. Tidal forces always act so as to synchronize the rotation rate with the instantaneous orbital speed, but such a synchronization cannot be maintained over mercury"s entire (eccentric) orbit. without the reoccurring phenomena of erosion and tectonic shifting, reshaping earth"s surface, the moon"s surface features date back almost to its formation. The primary agent of change on the lunar surface is from the impacts of interplanetary debris, in the form of meteoroids.