A Series of Conjunctions in the December Sky
Step out at sunset the next clear evening. Now and for the next couple of weeks, a gorgeous row of bright planets, like a string of pearls, graces the low southwestern sky from 5 to 6 PM each night. And this week, the Moon joins the show, pairing up with a planet each night!
December 6, 7, 8, 9, 10
Jupiter, Saturn, and Venus are getting together with the crescent Moon for a beautiful series of conjunctions. The show goes on all week as the Moon visits a different planet each night—from Venus on December 6, to Saturn on the 7th, and then Jupiter on the 8th. On the 9th and 10th, the Moon and planets will fully align across the southwestern sky.
- The brightest, lowest, and right-most object is Venus. It’s gorgeous. It’s been an evening star nearly all year long, but is now at its most dazzling.
- Look far to its upper right to the second brightest “star” and that’s Jupiter.
- Halfway between them is much dimmer Saturn.
If you have a telescope, Saturn will show off its amazing rings, while Jupiter will display one or more dark bands near its equator, as well as its four bright Galilean Moons. And Venus shows a thinning but ever-larger crescent shape, which is the best Venus ever offers.
December 10 and 11
On Friday evening, December 10, and Saturday the 11th, the Moon will hover on that same line, to the left of the planets. This line shows you the plane of the solar system, the flat, DVD-like shape upon which all the planets’ orbits, along with the Moon’s, are located.
This is worth a few minutes of your attention. You see, we normally use the horizon as our reference point. And while the horizon is always horizontal by definition, it’s in a different place depending on where you live. But that string of planets and the Moon? Well, that’s inviolable. Never-changing. The solar system’s flatness never alters its orientation in space.
One changes, the other doesn’t. Result? Well, if you visit the tropics the next few weeks, you’ll see that string of planets forming a vertical line upward from your horizon. But if you were in polar regions, the planet line would appear almost horizontal, barely angled above your horizon. So your earthly horizon changes, but that distant solar system plane—also called the ecliptic or the zodiac—holds its position. The angle it makes with OUR horizon tells us we are neither near the equator nor near the poles, but about halfway between the two.
Adopting that line, that plane as a reference point bestows an odd, epic sense of distance and grandeur. It’s a good thing. And it’s right there the next clear evening.