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andrew beech

on 21 March 2013

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Transcript of Exoplanets

Andrew Beech & Gregor Horne Exoplanets What are Exoplanets? The Kepler Mission Detecting Exoplanets Advantages of the Doppler Technique How the Doppler Technique can be used to find Exoplanets Disadvantages of the Doppler Technique Sources In 2009 Nasa launched the observatory probe, Kepler which was specifically designed to survey a portion of the Milky Way galaxy to discover dozens of Exoplanets in or near the habitable zone and determine how many of the billions of stars in our galaxy have such planets.

Since 2009 the Kepler mission has discovered over 2,854 exoplanets - including such curiosities as planets orbiting two suns! Exoplanets cannot be seen with the naked eye or even a telescope as, like all planets they orbit a star and the glare from the sun they orbit overwhelms them.
This means that they must be detected by other, indirect methods. The most common of which is the use of the Doppler Effect, indeed this is the technique used by Nasa’s Kepler mission. The doppler technique uses the doppler effect to analyse both the properties and motion of planets and stars.
Although it appears as though planets both simply orbit a star in fact both planets and starts orbit a common center of mass. (Often, due to the sheer size of the star the center of mass is actually within it.) 1 - The Doppler Technique is simple to use.
All you have to do is point a spectrometer at a star and observe how the spectrum changes.

2 - Planets can be found in almost any configuration.
Some techniques only work well if we can see the solar system edge on. Unless the plane the planet orbits in is perfectly perpendicular to our line of sight, we can "see" the planet. So that allows us to find planets in systems that we wouldn't be able to detect with other methods. Exoplanets or Extrasolar planets are planetary bodies which are located out with our solar system.

Astronomers have hypothesized about their existence for centuries but it was only as recently as 1992 that their existence was finally confirmed by astronomers Micheal Mayor and Didier Queloz.

Since then the number of exoplanets discovered has ballooned to 3,649! Exoplanets often orbit stars not dissimilar to our sun which has led astronomers to ponder as to whether there are some other habitable planets in the Milky Way, indeed astronomers from the Harvard-Smithsonian centre for astronomics suppose that there are 17 billion earth sized exoplanets in the our galaxy. bbc.co.uk
researched by gregor nasa.gov
researched by andrew wisegeek.com
researched by gregor lasp.colorado.edu
researched by gregor
When the star moves toward us, the light emitted has a shorter wavelength, so we say its spectrum is blue shifted. When it is moving away from us, the light has a longer wavelength, so we say its spectrum is red shifted.
Astrophysicists these redshift and blueshift values to determine both the planet's mass and distance from the star. We search for this spectral shift as it enables us to determine as to whether there are any planets orbiting the star. lasp.colorado.edu
researched by andrew The main disadvantage is that when we see the star wobble, that wobble is the combined effect of all the planets. That means if we do see a wobble, it can be very hard to determine if it is a big planet up close or lots of smaller planets dispersed around the star.

This has lead to the discovery of mostly gigantic Jupiter sized planets which are very close to their primary star.
For a while this left many astrophysicists pondering as to whether Earth sized planets were rare because few werebeing found. However it turned out that our first few methods were only good at finding specific types of planets. novacelestia.com
researched by gregor

planet-science.com researched by andrew
novacelestia.com If anything is orbiting the star, due to the affects of gravity it will begin to 'wobble'. The larger the mass of the object orbiting the star the larger the wobble. This wobble back and forth and alters the spectrum of the star
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