August Skies

Jon Spargo, New Mexico Tech Astronomy Club

August brings us the annual Perseid meteor shower. This year’s shower promises to be one of the best in recent years. The fun begins on the evening of August 11^th, and continues on the following evening of the 12^th. The really good news is that the crescent Moon will set just after sunset giving us a moonless night sky to view the Perseids. For those of you who can find really dark skies, there are predictions of up to 100 meteors per hour. For most of us, rates of 60 to 80 meteors per hour are more realistic. The peak of the shower should occur at about 2 a.m. on the 12^th.

Look to the northeast in the direction of the “W” of the constellation Cassiopeia. That is the radiant from which the shower will appear to originate. Over time, returning comet Swift-Tuttle has deposited numerous trails of cometary debris in the plane of the Earth’s orbit. Each year in early August the Earth plows through the debris trails, gravitationally capturing small chunks of cometary debris which become the Perseid meteors. These debris trails can be quite wide and so it is not uncommon to see a few Perseid meteors for a couple of weeks before and after the peak of the shower.

Brilliant Venus at magnitude -3.9 still dominates the early evening sky about 8 degrees above the western horizon, just after sunset. Mercury is lost to our view this month. Mars will also be very hard to find as it appears to hover only a couple of degrees above the western horizon at sunset.

The bulk of the planetary action this month falls to Jupiter and Saturn. The two gas giants are roughly 20 degrees apart and both reach opposition from the Sun this month. Saturn reaches opposition on the 2^nd and Jupiter on the 19^th. Both are well positioned roughly overhead at midnight or just after for naked eye, binocular, or small telescope viewing. Saturn’s magnificent rings are open to 18 degrees from horizontal. This should allow small telescopes to easily discern the major gaps in the rings.

The Moon will be new on the 8^th, first quarter on the 15^th, full on the 22^nd, and last quarter on the 30^th. Looking to the west on the 10^th, about 30 minutes after sunset, the slim crescent Moon can be found to the right of Venus. Looking to the southeast on the 20^th, about 45 minutes after Sunset, the nearly full Moon will be just below the ringed planet Saturn. On the following night, at about the same time and place, the Moon will be just below and to the right of Jupiter.

Due to Covid-19 restrictions, there will not be a first Saturday star party at the Etscorn Campus Observatory.

Clear Skies!

Jon Spargo. New Mexico Tech Astronomy Club

August 2021