Sky Watch by J. Alex Knoll

A Midsummer Night’s Treat

The moon bows out in time for this year’s Perseid meteor shower

The waxing moon reaches first-quarter Friday the 8th. As the sun sets, around 8:10, the moon is already more than halfway through the sky, shining in the southwest. By Sunday the moon appears due south at sunset and is accompanied by the brilliant red star Antares, the heart of Scorpius. Evening begins with Antares just three degrees ahead of the moon, and the two stay nearly as close as they trek westward until setting a little after midnight.

Tuesday and Wednesday evening, the gibbous moon hovers to either side of Jupiter, the dominant planet in our night skies. On the 12th, the moon is less than 10 degrees to the west of Jupiter, close enough that your fist held at arm’s length will obscure both. The following night, the two have switched positions, with the growing moon now little more than five degrees to the east of Jupiter.

As the moon waxes through the south, the constellation Perseus — focal point of the Perseid meteor shower — ascends the northeast horizon. This time each year, Earth passes through the debris-ridden tail of Comet Swift-Tuttle, causing these tiny bits of ice and dust to ignite as they cascade against the atmosphere. The tail of this comet is so long, wide and relatively fresh that you’re likely to see errant meteors for several nights before and after the peak during the wee hours of Tuesday the 12th.

One of the most consistent of the annual meteor showers, the Perseids can deliver upward of 75 meteors an hour between 2am, when the moon sets, and dawn. While these streaks of light appear to emanate from Perseus, the higher the constellation climbs, the more the meteors seem to come from every which way.

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