One of the funner facts about the night sky is that the constellation Taurus — the head of the bull — is made up of stars that are actually physically close to each other in space, and actually comprise a star cluster called the Hyades. This is unusual; in most constellations the stars appear close together in the sky, but are actually at wildly different distances from us, so they are actually widely separated in space, and only appear close together due to perspective.

The Hyades cluster (named after a sisterhood of nymphs) is about 150 light-years from Earth, and has about 100 stars in it spread out over several dozen light-years. Mind you, this is close enough to Earth to be bright enough to see many of the stars by eye, and big enough to be spread out fairly well on the sky. That’s why it makes up the bulk of what we see as Taurus.

Folks at the Space Telescope Science Institute in Baltimore (home of Hubble and JWST) put together a very cool animation showing what it would be like to travel in an immense circle around the Hyades, using real data for the star positions and colors. It starts off with the stars marked and connected by lines making the familiar V shape in the sky, but then things get distorted rapidly as we fly around them. Watch (make it full screen, too):

WHOA. There’s a lot to see here.

First, by coincidence, the bright star Aldebaran is located on the same line of sight to the cluster, even though it’s not actually a member of it! It’s much closer to us, about 65 light-years away. So it whips out of the view pretty rapidly.

Around 50 seconds in, Betelgeuse makes an appearance from the left, moving to the right, then swings back in from the right again. You can see it settling in at its familiar place to the upper left of Orion near the end of the video. Another red star blows past around 1:15, but I’m not sure what it is. Best guess is Mirach in Andromeda or Hamal in Aries.

Another funny coincidence here is that the iconic Pleiades cluster is close to the Hyades in the sky. Shaped a bit like the Little Dipper, the Pleiades is easily visible to the unaided eye even from mildly light polluted sites. It’s actually much farther away than the Hyades, about 450 light-years from us. It starts off to the upper right of the Hyades in the video. Keep your eye on it; as we move and parallax shows us the star’s physical layout in space. If you pay attention, you’ll see they appear to be quite elongated, with the long axis of the cluster pointed right at Earth! I am not sure if this is the real shape of the cluster or a problem with our distance calculation to the brightest stars in it; I wrote about this in detail on The Old Blog™ (and another astronomer, Guillermo Abramson, has also investigated this mystery). The distances are based on observations by the Gaia mission, and it struggled with the measurements for brighter stars. I don’t know if this has been solved in the years since I wrote about it. I’ll have to look into that.

Anyway, this animation tracks a staggering 11 million stars down to magnitude 13.5 (roughly 1/1000^th as bright as the faintest star you can see by eye in the sky) using Gaia data, as well as other catalogs to show dust clouds and the shape of the Milky Way in the background. Very cool! I love it when we can use data like this to get a better handle on the sky, especially when it’s surprising.

And don’t forget: the night sky is filled with stars at all different distances from us. We have no real sense of that relative distance, so our eyes file all of them under “infinitely far away”. But with our modern instruments we know that not only is that not true, but those distances can tell us a lot about the stars themselves.

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