PostHeaderIcon Exo-Earth around Gliese 581?

A new planet has been discovered around a distant star, not that this in itself would be news – it seems that new planets are discovered around other stars every few days. Usually, though, these planets are several times the size of Jupiter, or are sometimes as “small” as Uranus or Neptune. Though exciting, these planets aren’t the best fodder for science fiction enthusiasts and don’t inspire dreams about terra-forming Earth 2.0.

This planet is different. Creatively named “Gliese 581 c” this planet is only five times more massive than the Earth. More importantly, this new planet is within the “habitable zone” around its star. It orbits a lot closer (0.073 AU) to Gliese 581 than Mercury orbits around our Sun.

Habitable Zones

As you know, Mercury is one of the hottest planets in our solar system due to its proximity to the Sun; it would be a nasty place to live, and humans wouldn’t last long. The star Gliese 581 is different: it’s a red dwarf star, tiny, dim, and not very warm compared to our Sun. Assuming this planet is rocky like Earth, and has a bit of an atmosphere, this close orbit would make it perfect for liquid water.

In current astronomy, liquid water is the gold of the universe: the key ingredient needed to even hope that life exists on a planet or moon. The discoverers of this planetary system estimate that the average temperature on Gliese 581 c is between 0 and 40oC (32 and 104oF).

Earth 2.0?

So, it’s time to break out the terra-forming equipment, jump on the Enterprise, zip over and see what’s there, right? Well, perhaps we’d better invent light-speed travel first – Gliese 581 is still 20 light years away. On the other hand, perhaps we should protect the habitable planet we’ve got, and turn our terra-forming eyes back on re-terra-forming the Earth, and keeping it habitable.


Discovered by: Udry, Bonfils, Delfosse, Forveille, Mayor, Perrier, Bouchy, Lovis, Pepe, Queloz, and Bertaux from the Geneva Observatory, Switzerland.

Discovered using: the HARPS (High Accuracy Radial velocity Planet Searcher) instrument at La Silla Observatory, Chile.

Star: Gliese 581 is 20 light years away, in the constellation Libra. Though Libra is visible tonight (rising around 10:30pm), you won’t see Gliese 581 – it is too dim.

Planet: one of three planets discovered in the system so far, Gliese 581 c is 5.03 times the mass of Earth, orbits at 0.073 AU, and 1.5 times the diameter of Earth.

Alice Enevoldsen

Where’d I Get My Info? 313249A4883E6A86&chanID=sa007

The original press release by the ESO (European Organisation for Astronomical Research in the Southern Hemisphere):

The real deal – Here’s the scientific paper Udry et al submitted:

And their website:

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