Sky ArchiveTonight

Moon and Venus closest July 20

Before sunrise on July 20, 2017, look for the waning crescent moon and planet Venus in the eastern morning twilight. Or if you’re up before dawn, say an hour or two before sunrise, then let the predawn darkness show you the star Aldebaran and the Pleiades star cluster as well.

Although Aldebaran ranks as a 1st-magnitude star – and the Pleiades is highly recognizable for its dipper-like shape – both pale next dazzling Venus. Thus the light of the coming dawn can drown them from view.

If you’re up early enough, the predawn sky will show you the star Aldebaran and the Pleiades star cluster around now. The green line represents the ecliptic – the sun’s annual pathway in front of the constellations of the zodiac.

Venus – the most brilliant planet – ranks as the third-brightest celestial body to light up the heavens, after the sun and moon. Venus shines nearly 100 times more brilliantly than Aldebaran, the brightest star in the constellation Taurus the Bull.

Our sky charts are designed for mid-northern North American latitudes. But don’t let that stop you from looking! No matter where you are on Earth, simply look for the moon in the eastern sky before sunrise, and the two starlike objects close by on July 20 will be Venus and Aldebaran.

Need more precision? Residents of the world’s Eastern Hemisphere – Europe, Africa, Asia, Indonesia, Australia and New Zealand – will see the moon offset to the west (farther away from the sunrise point) relative to Venus and Aldebaran. We in North America see the moon to the east of Aldebaran on July 20. People in far-eastern Asia, Indonesia, Australia and New Zealand will see the moon to the west of Aldebaran on this same date.

But if you live in India, Pakistan or Afghanistan, it’s possible that you won’t see Aldebaran to the west of the moon – or to the east of moon in tomorrow’s July 20 predawn/dawn sky. That’s because the moon will actually occult (cover over) Aldebaran in this part of the world, with Aldebaran slipping behind the moon’s illuminated side and then reappearing from behind the moon’s nighttime side.

The area between the solid white lines shows where the lunar occultation of Aldebaran will happen in the predawn sky and in between the blue lines at dawn. Worldwide map via the International Occultation Timing Association (IOTA).

For instance in Calcutta (Kolkata), India, the moon will occult Aldebaran on July 20, 2017, from 3:37 to 4:39 a.m. local time (UTC + 5:30). Click here for more information, remembering that you must convert UTC to your local time.

Bottom line: Around the world on July 20, 2017, the moon and Venus will be close in the east before dawn. The bright star nearby is Aldebaran in Taurus the Bull. If you catch them long enough before sunrise, you might also see the dipper-shaped Pleiades star cluster above Venus, the moon and Aldebaran.

July 19, 2017
Sky Archive

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Bruce McClure

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