Astro4 Exam 1 Guide

Astro4 Exam 1 Guide - Questions from "The Search for...

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Questions from "The Search for Alien Worlds" episode of Mysteries of Deep Space How are astronomers searching for planets around other stars? Why is it so hard to do? The current searches for "exoplanets" concentrate on finding effects of planets on their stars, rather than trying to image the planets themselves. It is a hard thing to do because current technology is just not up to the task of discerning a small, faint thing (a planet) next to a very brilliant thing (the star it orbits around) at interstellar distances. The effect of planets on their stars that this video depicts astronomers measuring is their gravitational effect. How are astronomers searching for evidence of extraterrestrial intelligence? They are doing so by searching for artificially-generated radio radiation from space. What evidence is there that life might exist elsewhere in our solar system? Not much. The program showed several phenomena that can be interpreted to indicate that life might exist (or have existed) elsewhere, but they aren't at all conclusive. Those phenomena include dry river beds on Mars (where liquid water cannot exist now) and the possibility of liquid water under the icy surface of Europa, a moon of Jupiter. Liquid water, thought to be essential for life, is a rare substance on or near the surfaces of solid bodies in the solar system. What's “odd” about some of the planets around other stars that have been discovered so far? Based on the general characteristics of our own solar system (in which giant, "Jovian" planets are found only far from the Sun) and on our understanding of how large, hydrogen and helium planets like Jupiter form, we didn't expect any very large planets to be found close to their stars. Surprise, surprise! Many of the planets listed on ( Marcy's site , cited above) are very large planets very close to their stars. It should be noted, though, that the search techniques used will produce the strongest, quickest results for just that kind of planet. Smaller planets farther from their stars will produce much weaker results that will take much longer to detect. Who are Geoff Marcy and Paul Butler? They are leaders in the search for planets around other stars. When this program was produced (1997), they were at San Francisco State University. Currently (early 2007), Marcy is with the University of California at Berkeley, and Butler is with the Carnegie Institution of Washington, working primarily at the Anglo-Australian Observatory. Observing the Sky What is the celestial sphere? It is an imaginary sphere around the Earth to which the stars appear to be attached. It seems to rotate around us from East to West with a period of 24 hours, thus causing things like the Sun and Moon to "rise" and "set" What is a constellation? It is an area of the celestial sphere denoting a direction in space away from the Solar System.
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Astro4 Exam 1 Guide - Questions from "The Search for...

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