Before sunrise on August 14, 15 and 16, 2020, watch for the waning crescent moon to pair up with the dazzling planet Venus in the predawn sky. Even as dawn breaks, it’ll be hard to miss these two brilliant and beautiful celestial bodies. If you’re watching in early morning darkness – especially if you’re in a rural location – you might also see a sprinkling of Perseid meteors, although the Perseid shower is past its peak now and the meteors numbers are falling off rapidly.
The sky chart above shows the moon and Venus as they appear at mid-northern latitudes in North America. For a specific view from your particular location on the globe on these mornings, try Stellarium.
Keep in mind that the moon appears larger in our chart than it will in your actual sky. But, no matter where you live, the moon will be in the vicinity of Venus on all three dates: August 14, 15 and 16. And no matter where you live, the moon travels in front of the constellations of the zodiac at the rate of about 1/2 degree (the moon’s own angular diameter) eastward per hour, or about 13 degrees eastward per day.
Find out which constellation of the zodiac is presently behind the moon via Heavens-Above.
With the moon there to assist you, this is a great time to look for Venus in a daytime sky. Sharped-eyed people can pick out Venus in a daytime sky with the unaided eye. Want to try your luck? First look for the moon, then seek out Venus. Or aim binoculars at the moon to view Venus nearby. A typical binocular field spans about 5 degrees of sky. From a whole-Earth perspective, the moon will pass 4 degrees north of Venus on August 15 at about 13:00 UTC. This is a great month for viewing Venus in daylight, because Venus reached its greatest elongation from the sun (45.8 degrees west) on August 13.
Although the moon and Venus appear close together on the sky’s dome, they are not truly close together in space. At the time that the moon swings by Venus, the moon will be very close to its average distance from Earth (238,855 miles or 384,400 km). Venus, at a distance of about 0.73 astronomical units (one astronomical unit = sun/Earth distance), is over 280 times the moon’s distance from Earth.
Find out the moon’s present distance from Earth via The Moon Tonight.
Find out Venus’ present distance from Earth and the sun via Heavens-Above.
Because Venus is an inferior planet – a planet that orbits the sun inside Earth’s orbit – Venus goes through phases, like our moon. However, you need to use a telescope to see Venus’ phases.
You might think that the moon and Venus should display a similar phase in the morning sky, given that these two luminaries are nearly on the same line of sight. But no, that is not the case. As the moon sweeps by Venus, the waning crescent moon will be about 15% illuminated by sunshine, whereas Venus will be just a touch past (51% illuminated) its half-illuminated first quarter phase.
Whenever you see the moon and Venus together in the morning sky, the moon is always waning while Venus is always waxing. The converse is also true: whenever you see the moon with Venus in the evening sky, the moon is always waxing while Venus is always waning. That’s because the moon orbits Earth whereas Venus orbits the sun.
When the moon is at first or last quarter phase, the sun-Earth-moon makes a 90-degree right angle in space, with Earth at the vertex of this right angle. (See illustration above.) On the other hand, when Venus is at first or last quarter phase, the sun-Venus-Earth also forms a 90-degree right angle in space, except that it’s Venus that’s at the vertex of the right angle. (See below.)
Bottom line: Enjoy the moon and Venus as they beautify the morning sky in mid-August 2020!