Planets over the Potomac: Summer nights heat up planetary performance

SumTriangleDC

As the heavens get dark, look to the east. The Summer Triangle’s Vega will already be high in the sky, with Deneb and Altair following. The image depicts the view looking east around 9:30 p.m. (Blaine Friedlander/Dan Stillman)

It’s got to be a summer of love: Find Venus – named for the Roman goddess of love – puttering around at dusk, Saturn brings some rings and you get caught up in a triangle.

The cosmic action starts at sunset: Find Venus at dusk now loitering each evening in the west-northwest.  It’s a stunning -3.9 magnitude, very bright and you should be able to see it easily from urban and suburban locations.

On Wednesday a very young, skinny and shy moon will be low in the western sky.  With a clear view of the horizon, see the new waxing moon and Venus in the same region. It’s not a conjunction, but from our earthly perspective the moon is about 7 degrees from Venus. Find the crescent moon to the lower left of the bright planet.

Venus is quite prominent.  If you’ve never made a point to know this planet, this may be a great summertime opportunity.  Astronomers often describe Venus as looking like an airliner on approach with its landing lights on.

By Thursday night, the moon will have moved away from Venus.  Our lunar buddy gets a shade brighter and bit thicker, hanging out near the constellation Leo, heading toward the constellation Virgo. The moon and our effervescent neighbor Venus will be about 12 degrees apart. Catch this planet while you can, since Venus now sets after 10 p.m.

Turn your head south to spy Saturn.  Our large, gaseous ringed-planet crosses south at sunset. Find the zero-magnitude planet – bright enough to see through the muggy Washington heavens – in the constellation Virgo.

Throughout this upcoming weekend, the fattening moon begins an approach toward Saturn. The new moon develops into the first quarter moon on Monday, July 15. The pleasantly more-plump moon sneaks underneath Saturn on Tuesday, July 16, and from our perspective the two objects are about 4 degrees apart. Saturn now sets around 1:40 a.m.

You can’t discuss the summer sky without mentioning the Summer Triangle, which features three of brightest stars in the heavens.  This prominent isosceles triangle features Vega, in the constellation Lyra and the fifth brightest (-0.03 magnitude) star; Altair, in Aquilla, the Eagle, ranked 12th in brightness (0.76 magnitude); and Deneb, in Cygnus, the Swan, ranked 20th in brightness (1.25 magnitude), according to the Royal Astronomical Society of Canada.

As the heavens get dark, look to the east.  The triangle’s Vega will already be high in the sky, with Deneb and Altair following.  In a very dark sky, where you can see the stream of the Milky Way, the stars Deneb and Altair sit in the middle of the Milky Way flow, while Vega sits on the banks of the cosmic canal.

From dusk to dawn, the Summer Triangle joins us all night. It ascends the east, climbs overhead in the dome of our sky, and then sets in the west as dawn approaches. Which star is which: In the east, Vega is the highest.  Deneb will be to Vega’s lower left, while Altair will be to Vega’s lower right. When the asterism prepares to set in the west, the bright Vega goes first. Altair is to Vega’s upper left, while Deneb is above Vega.

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