Moon-Venus-Encke-Mars-Uranus congress

A gathering in the evening sky.

In this picture, the Moon is exaggerated 4 times in size, Venus 150 times, so as to show its changing crescent shape.  The arrows through the moving bodies show their changes of position, relative to the stars, from 2 days before to 2 days after the date.

In the foreground the Moon hurries “leftward” (eastward); farther off, Venus and Comet 2P Encke fall in the opposite, sunward direction.  In the background, Mars and Uranus are progressing eastward around their orbits, though too slowly to keep ahead of the apparent movement of the Sun.

All these travels are approximately in the plane of the ecliptic, and they bring the shining bodies into a temporary, extended, evolving cluster – first a western Moon-Encke-Venus cluster, then an eastern Moon-Uranus-Mars cluster.  For the details of when the pairwise conjunctions happen, see the table in “Astronomical Calendar 2017” above.

Orbits of the planets and Comet Encke, and their paths in February and March, with sightlines from Earth at March 1.  The Sun is exaggerated 5 times in size, the planets 300 times.  The dashed line and ram’s head symbol represent the vernal equinox direction.


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