Conjunction: From One End To The Other

If there were ever a night for a romantic sunset, this is it. Don’t go in when the sun goes down, though! That can wait an hour or so. Treat yourself and your sweetie to an alignment of the crescent moon, Venus, and Jupiter in the western sky of Earth.

I hope your skies are more cooperative than mine; we had our first significant snowfall of the season here in central Iowa. Looks like about two inches of frozen water on the ground and a few thousand feet of vaporous water in the air. I don’t think Ames will be a conjunction junction tonight. Unless it were to be tv, blanket, couch, and spouse.

The moon and planets aren’t actually passing close to each other in space. The moon orbits us. Venus orbits the sun inside the Earth’s orbit and is almost 200 times farther away than the moon. Jupiter is at least ten times farther away than the inner planet. This conjunction of celestial objects is one of those occasional accidents of celestial mechanics when two or more objects pony up in our line of sight.

Tammy Plotner at Universe Today gives some background on what’s happening inside the human head to get you all excited about celestial sights like this.

For every conjunction we see on Earth, there is a similar experience on the other end. In a few centuries, perhaps, when human explorers have spread through the solar system, they will experience their own set of conjunctions. And if we were viewing one of their planets on the far end of a celestial alignment, they would see us on the tail end of such a sight in their skies or scopes.

Astronauts near Jupiter today would experience a similar conjunction of the Earth, Luna, and Venus. That formation would appear close to the sun–about ten degrees away, double the approximate width of your fist at arm’s length.

Just for fun, I ran some simulations from a few of Jupiter’s moons, looking back at Earth. And look at the view I found for 0345UTC today from the moon Europa, just about at the time I was blogging this entry:


I know the text is mushed together, but this 20 degree field gives you the sun, too. Surprise: another Jovian moon, Callisto, appears on top with a very small crescent, the plus marks the moon and Earth really close together and the yellow point marks Venus. Here’s a view from binoculars:


This field of view is about the size of the Big Dipper’s “bowl.” A nice reversal, isn’t it? As Earthlings look into the west and marvel at a moon and two planets, Europans (if there were any) look back at us and see two planets and two moons.

And if, by chance, your skies are cloudy, rainy, or snowy, you may miss your chance at the moon hustling into conjunction junction. But keep a close watch on the two planets in the days ahead as they move relative to each other and to the background of other stars or your local horizon. A good home project for your astro-minded kids would be to track the planets over several days. Be sure to catch the sight at the same time each day and add local landmarks like trees, housetops, and the like.

Lots to think about, but if you’re actually enjoying celestial sights with the one you love, don’t let your brain work too much on this stuff. Just sit back and enjoy.


About catholicsensibility

Todd lives in the Pacific Northwest, serving a Catholic parish as a lay minister.
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One Response to Conjunction: From One End To The Other

  1. crystal says:

    I saw the three of them last night. Maybe I’ll try to take a photo tonight :)

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