Name: 外惑星の探し方 (How to Find an Exoplanet)
Uploaded: 2021-01-14T10:19:54.000Z
Duration: 2 min 36 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

様態の副詞

So how on earth, does one find a planet orbiting a distant star?

that its really hard to just look at one, and see a planet orbiting it.

with very large planets, very far away from them.

Think 10 times the size of jupiter, and an orbit at least as big.

have been found indirectly, by observing their effects on their parents stars.

For example, a planet passing in front of a star will make

and the amount it darkens, will tell you about the size of the planet, relative to the size of the star.

of course this only works if the planets orbit is tilted perfectly to pass between us and its star.

and on average less than 1% of earth like planets will have this convenient orbital orientation.

We have managed to find a lot of exoplanets this way,

but you could instead have a look at the effect planets have on the motion of stars.

Rather, both orbit around their combined centre of mass.

Stars are so heavy, so often the centre of mass is inside the star,

That motion manifests itself as a teeny tiny wobble,

in the velocity of the star relative to us.

which we determine by carefully measuring the red or blue doppler shift

both these indirect methods are most effective at finding big planets,

because the speeds involved, and the amount of light blocked

are greater, and also because close planets orbit more often

so we don't have to wait as long to notice their effects.

There are other more complicated and fancy methods which can find planets

which are harder to notice by a star wobbling or star light blocking

and all of these together have helped to discover

This video is brought to you in part by Audible.com,

The leading provider of audio books across all types of literature, including

you can try Audible out by downloading a free audiobook of your choice.

I would like to recommend the book 'Foundation'.

opening saga about the impending collapse of interstellar civilisation.

You can download your free audiobook at Audible.com/minutephysics

and I would like to say thanks to Audible for helping me continue to make these videos.

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外惑星の探し方 (How to Find an Exoplanet)

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