How do you detect planets around other stars?

Answer 1

The main way is the Doppler shift of light from the star. Earth does not really orbit the Sun, the Sun and Earth orbit EACH OTHER, around their common center of mass. Since the Sun is MUCH larger than Earth, that center is very near the center of the Sun, deep inside but not at the exact center. But if there were two equal size Suns, they would orbit each other around a point half way between them. So a large planet can make the star it orbits move quite a bit around a point pretty far from it's center, and this motion can be measured by the Doppler shift in the spectrum of light from the star. But the effect is small, even for planets bigger than Jupiter, so you need a big telescope and high resolution spectrograph to detect it. It is really hard to do. And the bigger the planets is, the easier it is to detect. That is why most of the extrasolar planets discovered are giant planets.

Another way is if the planet's orbital plane is exactly parallel to our line of sight to the star, the planet can pass in front of the star as seen fron Earth. That blocks some of the starlight, kind of like an annular eclipse, and if we can measure the brightness of the star very accurately and continuously, we can detect that transit, or eclipse.

Answer 2

The method of detecting planets around other stars is fairly simple, once someone showed the rest of us how to do it.
You use a telescope with a camera attached, and over several months and even years they take photos of the star, and if the star has any planets orbiting it the gravity of the planet tuges on the star and when you look at the photos at a fast speed you can see the wobble of the star caused by the panets.
If you want to test this method to see how it works, get a piece of rope about five to eight foot long, tie a weight lets say a brick to the end of the rope, tale the other end in your hands and start spining it around over your head, you will fill your self being uolled by the brick making you wobble just like a planet makes a star wobble.

Answer 3

As you probably know the planets are too small and too close to the imense lilight thrown off by thier star to be observed directly. Observers use a trick that has to do with the planets gravitational influence on the star they are orbiting. From the observed "wobble" they can detrmine its orbit and mass.

Answer 4

scientists measure the amount a star "wobbles" in its rotation, the greater the wobble is the more gravity that is pulling on it and this indicates there is a planet orbiting it.
from this wobble they can estimate the size, nature of the planet and how far from the star it is.

Answer 5

There are a few ways of doing so. One is by noticing the star "wobbling". This indicates that it is being pulled gravitationally by some object that is orbiting it.