Thursday, 23 February 2017

Seven Sisters offer best chance to find alien life

Three of the seven planets have suitable conditions for life. Credit: NASA

NASA's Spitzer Space Telescope has found a system of seven Earth-size planets around a single cool dwarf star.

As many as three of these planets are firmly located in the habitable zone, the area around the parent star where a rocky planet is most likely to have liquid water. In fact, all seven might have water - they key to potential alien life.

NASA says this is the largest number of habitable-zone planets found around a single star outside the one we all know and love - Sol.

The ultra-cool dwarf star is called Trappist-1 and in contrast to our sun, it classified as an ultra-cool dwarf – is so cool that liquid water could survive on planets orbiting very close to it, closer than is possible on planets in our solar system. All seven of the planetary orbits are closer to their host star than Mercury is to our sun.

The planets also are very close to each other. If a person was standing on one of the planet’s surface, they could gaze up and potentially see geological features or clouds of neighboring worlds, which would sometimes appear larger than the moon in Earth's sky.

The planets may also be tidally locked to their star, which means the same side of the planet is always facing the star, therefore each side is either perpetual day or night. This could mean they have weather patterns totally unlike those on Earth, such as strong winds blowing from the day side to the night side, and extreme temperature changes.

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