Pretty planetary grouping
Published on Dec 1, 2008 at 3:31 pm.
1 Comment.
Filed under skywatching.
Tonight there will be a rather uncommon grouping of two planets and the Moon. Look in the southwestern sky and you’ll see the crescent Moon and two bright “stars” very near it. The brighter of the two stars is actually the planet Venus. The next one is the planet Jupiter. Click on the image above to see a bigger view of the scene. This is what it would look like from Texas at about 6:40 pm (except that around here the light pollution would wipe out most of the stars and the Milky Way).
These sort of groupings are not all that uncommon. Every few years there is a really nice grouping of planets, the Moon, or combinations of the Moon and planets. Jupiter and Venus, themselves, pair up every now and then. This time, the Moon is in the mix, and that makes this a bit rarer than most. The planets themselves were closest to one another some hours ago (last night, actually), and earlier today the Moon was actually in front of Venus, but the Sun was up here in Texas at that time, so we didn’t get a spectacular view of the occultation. Worse, the two were only just rising when the occultation was going on! For most of us, though, we miss the occultation (which is when one body passes in front of the other) and all we see is a conjunction (when they pass near one another).
However, that does not detract from the fact that this will be very pretty tonight. Venus and Jupiter will only be about two degrees apart tonight, and the Moon will only be about three degrees from Venus and four degrees from Jupiter, making nearly a right triangle for a while. All of this is going on with the stars of Sagittarius in the background.
This is not the first time that Venus has been part of a planetary grouping this year. Just three months ago, I wrote about a three planet grouping of Venus, Mercury, and Mars. So, Venus gets around. Now it is involved in a different trio of celestial bodies, but this time with the Moon and Jupiter.
As with the earlier grouping, we have an inferior planet (one closer to the Sun than Earth) appearing in the sky near a superior planet (one farther from the Sun than Earth). So, how is that possible? Well, quite simply, it is because Jupiter is on the far side of the Solar System from the Earth and Venus. If you were to go to Jupiter and look back and a little to one side of the Sun, you’d see something like the following image (once again, click on it to make it bigger and easier to see).
Here, we see that Venus and Earth appear near one another in the sky, as seen from Jupiter. In this case, though, they are less than half a degree apart in the sky, close to the diameter of the Moon as seen from Earth. The pairing of Venus and Earth in the sky would appear to be taking place against a backdrop of the stars of Gemini, as seen from Jupiter. However, all of this would be very close to the Sun in the sky, so it is unlikely that anyone at Jupiter would really be able to observe the close conjunction at all with the Sun’s glare in the way.
So, if you get a clear night, be sure to go out and look for the grouping.
-Astroprof
Images created using Starry Night Enthusiast
Chanwer on December 3, 2008 at 4:54 pm: 1
coolio