Stars-Distant Suns

Stars-Distant Suns - o killed 2/3 of all living species •...

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Stars: Distant Suns Craters are much larger than the meteors that make them o have a lot of kinetic energy—energy quickly dissipated Over 300 near-Earth asteroids with a diameter greater than 1 km One collision per million years, roughly 10^5 – 10^6 megatons of TNT Statistically, averaged over 100 million years, you are as likely to die from a cosmic collision as you are from an airplane crash, flood, or tornado An asteroid or comet with diameter greater than 10 km his Earth roughly every 100 million years o probably the end of human civilization 10^8-10^9 megaton explosion devastates a region of 1000 km o such a blast throws things into the atmosphere – carbonates o blocks the sunlight which stops photosynthesis and kills plants and then everything else in the food chain o Earth’s temperature is extremely hot o carbonates would rain down in the form of acid rain Apophis – asteroid that’s a near miss – will pass by Earth K-T extinction o Hypothesis: a comet impact caused the Cretacious-tertiary extinction
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Unformatted text preview: o killed 2/3 of all living species • Comet Shoemaker-Levy 9 collision with Jupiter o Comet with a diameter of 10 km o broke up into smaller bits o approached Jupiter with a speed 60 km/hr o Energies released were up to 6 million megatons of TNT o Could see the energy released in the infrared spectrum • Extra-Solar Planets o Giant planets like Jupiter have been found orbiting other stars o Doppler Effect – look for periodic wobble of a star due to the motion of a planet around it o Can calculate the mass of the planet using Kepler’s third law • Swiss team found star around 51 Pegasi o When masses are found you find the minimum mass o Most of the stars are barely visible to the naked eye distance is approximately 50 ly Technology at optical wavelengths is not yet good enough to detect Earth-sized planets very small orbits of some planets and high eccentricity o 1999 – 3 planet system found o A planet passed in...
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This note was uploaded on 04/04/2008 for the course ASTRO C 10 taught by Professor Filippenko during the Fall '08 term at Berkeley.

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