Posted on by Bob King

Venus And Moon Caught In A Crazy, Phase-y Coincidence Tonight

Curious coincidences occur in the sky just as they do on Earth. Take tonight for instance. The moon is in gibbous phase or about 3/4 full – 78% to be exact – while Venus, which also undergoes phases identical to the moon, is likewise gibbous and 78% full.

That’s just cool. If you have telescope, focus on Venus low in the western sky just after sunset and see a perfect replica in miniature of tonight’s moon.

Look for the cloudy but beautiful planet about a fist up in the west-southwest shortly after sunset. Stellarium
Look for Venus about a fist up in the west-southwest shortly after sunset. Stellarium

Be sure you’re out early as the planet is low to begin with and drops lower in the west with each passing minute. Provided the sky is haze-free, Venus isn’t difficult to spot even 5 minutes after sunset. Look about 10 degrees (one fist held at arm’s length) above the west-southwest horizon.

The moon and Venus are coincidentally in exactly the same phase tonight - 78% gibbous. Stellarium
The moon and Venus are coincidentally in exactly the same phase tonight – 78% gibbous. Stellarium

The moon shows spectacular craters and mountains, but Venus hides its equally spectacular scenery of volcanic mountains, craters and cracked plains beneath a permanent cover of sulfur-dioxide-laced clouds. Clouds are excellent reflectors of sunlight. Not only is the planet brilliant because of them but looks as white as a shiny cue ball.

Venus' changing position with relation to the Earth as it orbits around the sun causes it to exhibit phases like the moon. I've marked approximately where Venus is in mid-August. After gibbous, the planet will wane to half and then a crescent over the coming months as it catches up and passes the Earth. Illustration: Bob King
Venus’ changing position with relation to the Earth as it orbits around the sun causes it to exhibit phases like the moon. I’ve marked approximately where Venus is in mid-August. After gibbous, the planet will wane to half and then a crescent over the coming months as it catches up and passes the Earth. Illustration: Bob King

Tomorrow night the moon and Venus will go their own phase-y way, the moon fattening up toward full and Venus slowly slimming its waistline as it works its way toward the Earth. For now enjoy their temporary bond.

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