Are We alone; habitable planets? (Introduction)

by David Turell , Monday, May 02, 2016, 18:48 (3126 days ago) @ David Turell

Just because a planet is close to its sun does not make it habitable. It must be rocky and metallic. It must have an atmosphere. It must not get too much radiation from its star. this article is overly ecstatic and full of excuses in trying to overlook the problems with this discovery:-https://www.sciencedaily.com/releases/2016/05/160502111427.htm-Astronomers have discovered three planets orbiting an ultracool dwarf star just 40 light-years from Earth. These worlds have sizes and temperatures similar to those of Venus and Earth and are the best targets found so far for the search for life outside the Solar System. They are the first planets ever discovered around such a tiny and dim star. -***-"Michaël Gillon, lead author of the paper presenting the discovery, explains the significance of the new findings: "Why are we trying to detect Earth-like planets around the smallest and coolest stars in the solar neighbourhood? The reason is simple: systems around these tiny stars are the only places where we can detect life on an Earth-sized exoplanet with our current technology. So if we want to find life elsewhere in the Universe, this is where we should start to look."-***-"Follow-up observations with larger telescopes, including the HAWK-I instrument on ESO's 8-metre Very Large Telescope in Chile, have shown that the planets orbiting TRAPPIST-1 have sizes very similar to that of Earth. Two of the planets have orbital periods of about 1.5 days and 2.4 days respectively, and the third planet has a less well determined period in the range 4.5 to 73 days.-"'With such short orbital periods, the planets are between 20 and 100 times closer to their star than the Earth to the Sun. The structure of this planetary system is much more similar in scale to the system of Jupiter's moons than to that of the Solar System," explains Michaël Gillon.-"Although they orbit very close to their host dwarf star, the inner two planets only receive four times and twice, respectively, the amount of radiation received by the Earth, because their star is much fainter than the Sun. That puts them closer to the star than the habitable zone for this system, although it is still possible that they possess habitable regions on their surfaces. The third, outer, planet's orbit is not yet well known, but it probably receives less radiation than the Earth does, but maybe still enough to lie within the habitable zone."-Comment: I guess it is good to keep looking, but it should be with reasoned thinking, not grantesmanship optimism.-Note this thoughtful comment from another source:-"From their observations, the scientists determined that all three planets are likely tidally locked, with permanent day and night sides. The two planets closest to the star may have day sides that are too hot, and night sides too cold, to host any life forms. However, there may be a "sweet spot" on the western side of both planets—a region that still receives daylight, but with relatively cool temperatures—that may be temperate enough to sustain conditions suitable for life."- Read more at: http://phys.org/news/2016-05-years-earth-planets-host-life.html#jCp