August 20, 2019

Astro-Event of the Week: 05.04.09: The Eta Aquarid Meteor Shower.

This week, the second meteor shower of the season amps up; I give you the Eta Aquarids. This shower has a broad peak over the first half of May, and diligent observers may see up to 10-30 swift moving meteors per hour in the early AM hours. The further south you are, the better.  The radiant is very near the “Y” asterism in the constellation Aquarius, near the star Sadalmelik (Alpha Aquarii) and below the Great Square of Pegasus.

The Moon will be 86% illuminated at a waxing gibbous phase, and set at 4 about AM local time, giving about a one hour window before twilight begins to interfere. The actual peak is expected around Tuesday morning, May 5th, but of course, it’s always worth looking on either side of that date, as well. The parent comet of the Eta Aquarids is none other than the famous comet Halley.  This comet is also the source of the October Orionids. A burning mystery courtesy of Astroguyz; why are there virtually no large meteor shower radiants in the southern hemisphere?

This week’s astro-word of the week is antihelion. In addition to meteor shower outbursts throughout the summer such as the Eta Aquarids, there is a constant stream of sporadics that can be seen at a rate of four to five an hour. One source of these is the antihelion, or point opposite to the Sun. Thus, this point rises in the east at about the time the Sun sets, and rides highest at about just past midnight. The exact point lags a bit from true opposition because of the motion of the Earth around the Sun. These meteors are hitting us in a perpendicular direction and are neither exceptionally fast nor slow. See a meteor that doesn’t trace back to the Aquarius radiant? It may well be an antihelion sporadic!

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