Stars-Distant Suns

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

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
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
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

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 Keplers 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...
View Full Document

Ask a homework question - tutors are online