Sky Over Swarthmore: January 24, 2020

I’ve been noticing that Venus is very bright in the western sky after sunset. For the next few weeks, you can look for it between dusk and about 8 p.m., above and to the left of the place the sun has just set. Venus always appears near the sun in the sky. This is because Venus’s orbit is smaller than Earth’s, so when we’re looking toward the sun, we see them close to each other.

Early next week, Venus will be joined by the crescent moon. The planet will be shining brightly above the moon on Monday, and below and to the right of the moon on Tuesday. 

Of course, like the moon, planets shine by reflected sunlight. Just as the moon goes through phases, Venus goes through phases too. If our eyes were sharp enough, we could see the phase it’s currently in.

Image used by permission of Daniel Herron

Here is a nice composite image by Daniel Herron showing how the phases of Venus change over time. The images were taken, with a telescope, over a couple of months in 2016 and 2017.

Take a look at Venus with binoculars one evening. If your hands are steady enough, and the air is still enough, you may be able to make out its shape. It will be most crescent-like later in the winter.

Or it may just look like a quivering blob of light.

And, while you have your binoculars out, don’t forget to look at the moon! You’ll be able to see a lot of detail, like craters and mountains.

Astronomer’s note:

Astronomers capitalize not only the names of the planets, like Venus, but the names of our Sun and Moon when we’re talking about the heavenly bodies in our home solar system. However, since the Swarthmorean is a general interest publication, we will use lowercase for sun and moon, as people do in everyday writing.

By the way, we write galaxy but Galactic (if referring to the Milky Way). And if the multiverse is real, then Universe should be capitalized, since it’s one specific one (of many). But if it’s the only universe we have, then it’s universe.

– D.H.C.

David H. Cohen is a professor of astronomy at Swarthmore College.