Venus and the Pleiades shine in the west over the next week. Image credit: Phil Plait

Apr 7, 2015 Venus and the Seven Sisters

Sen—There’s a lovely dance going on in the western sky after sunset, and now is the best time to be watching it.

First, a related story: On Saturday, April 4, I happened to notice there would be a nice pass of the International Space Station over my home town of Boulder, Colorado. As a bonus, it would pass very close to the bright star Sirius, then a minute later glide across the sky near Jupiter. It was at about 8:30 pm local time, just as the sky was getting dark, so I knew I could get some pictures of it.

Despite clouds in the south I was able to see the pass and get a couple of decent shots. I don’t have terribly fancy equipment, just a digital SLR camera and a shaky plastic tripod. Still, even with the light pollution in my sky, I think I did OK. As you can see it did get pretty close to Sirius, and you might recognize the big guy on the right.


The International Space Station passes Sirius. Image credit: Phil Plait

After the pass, I turned to the west and saw Venus glowing like a beacon above the horizon. I also happened to see the Pleiades, a small cluster of stars nicknamed the Seven Sisters, just above it. Well, not one to waste an opportunity I took the picture you see at the top of this article. Given it was pretty much a point-and-shoot, I’m happy with it. Venus is obvious enough, and the Pleiades just above it. In the upper left you can see the “V” shape of the Hyades, a cluster of stars marking the head of Taurus, the bull, and on the right a few stars in Perseus and Aries as well.

And that brings me back to the point. Venus is coming around the Sun right now in its orbit, catching up to Earth. As it does so it slowly creeps eastward, away from the Sun, reaching its maximum distance from the Sun in the sky on June 6. In the meantime the Earth is going around the Sun as well, changing the positions of the stars in the sky; every day at sunset the Pleiades are a bit lower in the west.

Putting the two together, Venus will close in on the Pleiades, passing them at a remarkably close distance of just a couple of degrees, just the width of two fingers held at arm’s length. That will happen on Saturday, April 11.

But all this week they’re close, and getting closer. Many astronomical events can take months to unfold, and others mere hours. I prefer ones like this! The anticipation, the slow encroachment of Venus is delicious, and there’s the added benefit that if it’s cloudy one night you don’t miss the whole thing.

And there’s something truly wonderful about watching the clockwork sky tick away. It can be hard for people to visualize all the different motions and cycles in the sky, but in this case you can see it for yourself, and you don’t have to wait weeks or months for it to become obvious. If you go out two nights in a row this week you’ll see the difference, with Venus noticeably closer to the cluster.

Taking pictures is easy enough; both Venus and the Pleiades are bright, so short exposures will pick them up. If you have binoculars, all the better! That’s where the cluster really looks best; telescopes tend to let you only see one part at a time, while binoculars let you grasp the whole group.

You can also check your eyesight and how dark your sky is; how many stars in the Pleiades can you see with just your naked eyes? Check using binoculars. You can also try your hand at sketching the stars as you see them; I’ve found that actually helps me find fainter, more difficult stars. It adds to the delight of observing. It doesn’t matter if you can draw well or not; just the attempt will help train your eyes to see better.

The best part? You can easily share this with others! Tell your family, your friends, your neighbours. Watch the skies!

And who knows, there may be a decent pass of the space station or other satellites you can watch as well. I use Heavens Above to check; enter your location and then see if there may a nice surprise to add to your observing.

Go outside! Look up! There’s a whole sky up there.