Liquid water is a prerequisite essential for life as we know. Almost any kind of life is based to some extent in the presence of this molecule that consists of an oxygen atom and two hydrogen atoms. 50% of the mass of the human body is due to water. To keep liquid on a planet, it requires a proper air pressure and an average temperature suitable. Circling the star Gliese 581 has found a planet that may have just the right values \u200b\u200bof pressure and temperature to hold liquid water, and thus one of the modules necessary for life. The planet named planet G is in the habitable zone, which means, at a distance from the star where temperatures are neither very high nor very low. It also has a mass similar to Earth, allowing an atmosphere similar to ours. These two factors together mean that liquid water can exist on its surface.
Steven Vogt of the University of California Santa Cruz and colleagues describe here the reanalysis of their data. Over 11 years accumulated spectrum of the star Gliese 581, and comparing these with data acquired by other techniques, conclude that there are two additional planets to the four already known. The interesting thing is that for the first time there is a planet right in the middle of the habitable zone. I've written before about the search for exoplanets with the Kepler space telescope, planets that circulate to other stars and not the sun Although Kepler is becoming more exoplanets, these new results were acquired with telescopes stationed on Earth, especially with the WM Keck Observatory Hawaii. Is measured with a spectrometer emititda radiation by the star. Small changes in wavelength of this radiation indicate the presence of planets. The magnitude of the change in wavelength depends on the mass of the planet and its distance from the star.
Image: Comparison of the orbits of Mercury, Venus and Earth in the solar system Gliese 581. The Gliese 581 system is much smaller than our solar system. (Image from Steven Vogt, http://www.ucolick.org/ ~ vogt /)
Planet G has at least three times the mass of Earth. It's enough to trap gas in its surface and create an atmosphere. The moon, by comparison, has no atmosphere because of their small mass, one sixth that of Earth. A year on the planet G has only 37 days and the distance to the sun is about one sixth of the Sun to Earth. In our solar system would mean very high temperatures on its surface. But Gliese 581 is a red dwarf, dimmer and cooler than the Sun to planet temperatures may be similar G to ours. It is also curious that there is no day. As always see the same side of the Moon from Earth, the planet G always shows the same side towards Gliese 581. So on one side is always the other day while in perpetual darkness rules.
course, the results do not confirm the presence of liquid water on the planet. All you can say is that there is some likelihood of its surface. And with the water, extraterrestrial life becomes a real possibility. Steven S.
Vogt, R. Paul Butler, Eugene J. Rivera, Nader Haghighipour, Gregory W. Henry, & Michael H. Williamson (2010). The Lick-Carnegie Exoplanet Survey: A 3.1 M_Earth Planet in the Habitable Zone of the Nearby Star Gliese 581 M3V arXiv arXiv: 1009.5733v1
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