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Unformatted text preview: Finding Exoplanets Astronomers cannot yet determine the diameters of most of the giant exoplanets so their densities, and, therefore, their composition is still unknown. Eighty-one of the giant planets has been observed to move in front of their stars and cause an eclipse or dimming of the starlight. This is called a transit so this means of detecting planets is called the transit technique. A transit means that the planet's orbit is aligned with our line of sight (and the inclination angle is nearly 90 degrees). From the planet transit, astronomers have been able to accurately measure the diameter of the planet. Using the planet mass from the star wobble methods you can then determine the density. Careful observations of the spectrum of the star while the planet is transiting across will enable astronomers to determine the chemical composition of the planet's atmosphere using spectroscopy. In other cases, the planet's spectrum is found from taking the spectrum of the star plus planet, then taking the spectrum of just the star when the planet is...
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- Fall '10
- Astronomy, Planet