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Visualizing the Universe, Part V: Gliese 581
The faint star Gliese 581 has been getting a lot of press lately: it's the first star known to have a fairly small planet in its habitable zone, or the region of space where liquid water can exist. Although we've found a few other planets in (or close to) probable habitable zones, they've been much larger. The recent discovery appears to be only a few times more massive than the Earth, rather than hundreds or even thousands of times more massive, as many exoplanets are.
What kind of star is Gliese 581? For one thing, it's not very much like the Sun. It's much dimmer. In fact, even though it's about as far away as stars like Fomalhaut and Altair, it's much too dim to be seen with the naked eye. Here's where it is in our sky. It's in Libra, not too far from the bright stars of Scorpius:
After the break, we're going to take a trip to Gliese 581 and look around.
Let's go. Gliese 581 is about 20 light-years from Earth, which is fairly close as stars go.
You have to get more than halfway there just to see it! Gliese 581 is a red dwarf, a small, cool star that is only about 1% as bright as our Sun.
Gliese 581 is close enough that the familiar constellations from Earth are mostly intact, but distinctly different. Let's start here, near where Gliese 581 is in our sky, and then swing around and look for the Big Dipper:
and from there, let's go to the galactic center region.
Scorpius looks mostly the same, but Sagittarius is rather bent out of shape. In fact, its western stars (Gamma, Delta, Eta, and Kaus Australis, along with HR 6630) form a broad, bright arc that puts Earth's Corona Australis to shame.
Finally, let's swing around to Orion:
Almost completely unchanged, but since the Sun is in this general area, some stars that are especially close to the Sun, like Sirius, are very far from their usual places.
After a while, though, there really is no place like home.