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Is There Another Planet? CNN Clip New Planet 2011 What are two similarities that you heard in these two videos? But if the goal is to find planets with evidence of life, the ones discovered so far are not good candidates. Most of new discoveries are gas giants like Jupiter or Saturn and in the wrong location. The right location in our solar system. 17 Many of the new planets get too hot or too cold to support life. Too hot! Just right! Too cold! Most of them have highly elliptical orbits, or are too close to their parent stars. Requirements For Life Needs to be… In a solar system with a single massive star that can serve as stable source of energy A terrestrial planet (non-gaseous) The right distance from the sun If it’s too close, the water is burnt off, if it’s too far, the water is permanently frozen Finding another Earth won’t be easy because: 1) Earth-like planets are small, and 2) Planets are relatively close in to bright stars. The planets discovered so far are closer in mass to Jupiter. This is what we’ve found This is what we are looking for Jupiter’s diameter is eleven times greater than the Earth’s, and it has over 300 times the mass. Stars are a billion times brighter… …than the planet …hidden in the glare. Like this firefly. Requirements For Life Needs to have… A moon of sufficient mass to stabilize the tilt of the planet’s rotation Plate tectonics An oxygen-rich atmosphere A sweeper planet to deflect space debris (comets) Planetary neighbors that have non-eccentric orbits And how will we know a planet supports life? Look for evidence of oxygen Analyze the reflected light from the planet to see if the planet has an atmosphere Look for liquid water Look for signs of biological activity (methane) and rule out other explanations. 17 Two Key Terms Habitable Zone - the zone around a star where a planet could experience temperatures like those on Earth and life as we know it could exist Goldilocks planet - is a term for a planet that falls within a star's habitable zone, specifically used for planets close to the size of Earth