Stars Crowd Around the Moon This Weekend

Of the ten first magnitude stars in the heavens, eight of them will surround the Moon.  So let’s have some fun with this. 

• Look all around the Moon at those bright stars. First look for color. It’ll take just a few seconds to see that they’re not all white. They’re pastels. So happens, there are no green stars in the universe. But there are light blue and orange stars galore, and this weekend a bunch of those surround the Moon.
• The colors tell tales. The bluish ones are the hottest and youngest. The orange ones are the coolest in the temperature sense.
• You’ll notice that the star directly below the Moon, meaning the lowest down of all the stars, is also the very brightest. This blue gem is the famous Dog Star—Sirius. It also happens to be the very closest star we can ever see from the US, Europe, or Canada without a telescope.
• The orange star to the right of the moon on Saturday is Aldebaran in Taurus the Bull.
• The orange star to the lower right of the moon Sunday night is Betelgeuse in Orion.

But why are they all concentrated in this one area? Look around the rest of the sky and there is no other place that has such a bunch of bright stars gathered together like this.

he reason is that right behind the Moon this weekend is the nearest spiral arm of our galaxy, the Orion arm. It’s a place where there is enough free hydrogen gas that new star formation is active. The center of all this starbirth is Orion, below the Moon.

So it’s all very majestic. And lovely. And it sure takes our minds away from events in Washington. Whoops, sorry I said that.

For the next sky event, see my column on the January 31 Full Perigee Moon Eclipse—what’s being called a “Super Blue Blood Moon Eclipse.”