![\"\"](\"http:\/\/www.starshipnivan.com\/blog\/wp-content\/uploads\/2010\/09\/Gliese-hab-zone.jpg\" "\\"Gliese")
<\/a><\/p>\nThe Gliese 581 system has a persistent will-o-the-wisp quality.\u00a0 Almost each of its planets (c, d, e and now g) has been pronounced in turn to pass the Goldilocks test, only to have expectations shrink when the data get analyzed further.\u00a0 The first frisson of excitement arose when 581c was determined to be Earth-type, which quickened the usual speculations: atmosphere? water? life?\u00a0 We don’t know yet and our current instruments cannot detect biosignatures at that distance (short of an unencrypted request for more Chuck Berry).\u00a0 But there are some things we do know.<\/p>\n
Gliese 581 is a red dwarf, a BY Draconis variable.\u00a0 This makes it long-lived; on the minus side, it may produce flares and is known to emit X-rays.\u00a0 Planets in its habitable zone are so close to it that they are tidally locked, always presenting the same face to their star.\u00a0 The temperature differentials resulting from the lock imply hurricane-force winds and tsunami-like tides.\u00a0 Gliese 581g, like 581c, is large enough to retain an atmosphere; the hope is that, unlike 581c or Venus, its specific circumstances have not resulted in a runaway greenhouse effect.<\/p>\n
The real paradigm shift is the discovery that this solar system has many earth-size rocky planets, in contrast to the hot-Jupiter\/hot-Neptune preponderance in most others.\u00a0 The second enticing attribute of Gliese 581 is its relative closeness — a distance of merely 20 light years.\u00a0 It is still millennia away by our present propulsion systems.\u00a0 But I nurse the dream that if we see anything remotely resembling a biosignature, we will strive to reach it.\u00a0 In the meantime, I suggest we give it a name that fires the imagination.\u00a0 Perhaps Yemanj\u00e1, the Yoruba great orisha of the waters, in the hope that the sympathetic magic of the name will work.\u00a0 Perhaps Kokopelli, the trickster piper of the American Southwest cultures, who may entice us thither.\u00a0 I will conclude with the final words of my first article on Gliese 581<\/a>:<\/p>\n “Whether Gliese 581c [g] is so hospitable that we could live there or so hostile that we could only visit it vicariously through robotic orbiters and rovers, if it harbors life \u2014 even bacterial life, often mistakenly labeled \u201csimple\u201d \u2014 the impact of such a discovery will exceed that of most other discoveries combined. Unless supremely advanced Kardashev III level aliens seeded the galaxy like the Hainish in Ursula Le Guin\u2019s Ekumen, this life will be an independent genesis, enabling biologists to define which requirements for life are universal and which are parochial.<\/p>\n Images: Top, comparison of the Sun and Gliese 581 habitable zones (the diagram is by Franck Selsis, Univ. of Bordeaux; the image of 581g was originally created for 581c by Ginny Keller<\/a>); bottom, Kokopelli playing his flute.<\/p>\n<\/a>At this point, we cannot determine if Gliese 581c [g] has an atmosphere, let alone life signatures. If it has non-technological life, without a doubt it will be so different that we may not recognize it. Nor is it a given, despite our fond dreaming in science fiction, that we will be able to communicate with it if it is sentient. In practical terms, a second life sample may exist much closer to home \u2014 on Mars, Europa, Titan or Enceladus. But those who are enthusiastic about this discovery articulate something beyond its potential seismic impact on biology and culture: the desire of humanity for companions among the sea of stars, a potent myth and an equally potent engine for exploration.”<\/p>\n