Sunday, March 22, 2015

A month later

Venus, Moon, Mars (faint dot at lower right of the Moon), Mar 21, 2015 evening

Moon, Mars (middle), Venus, on Feb 20, 2015 in the evening sky.

The top image shows Venus, Moon, and Mars yesterday evening. For comparison, the same three as they appeared exactly four weeks ago, shown above. The Moon has completed one orbit around the Earth, The Earth has moved about thirty degrees along its once-a-year orbit around the Sun. Venus, whose orbit is inside the Earths orbit and moves around the Sun more quickly, is starting to catch up to Earth. Mars, with its orbit outside the Earths orbit, moves more slowly than Earth. Mars, on the far side of its orbit (as seen from Earth) at this time, will disappear behind the Sun in a few weeks, and will then re-appear in the morning sky. This comparison is a good demonstration of the dynamic behaviour of the solar system.
Click on the images for a larger view, or use Zoom option.