Subj : Re: Study Suggests There Are 300 Million
To   : Charles Pierson
From : Tony Langdon
Date : Sat Nov 14 2020 20:55:00

-=> On 11-13-20 06:11, Charles Pierson wrote to Tony Langdon <=-

 CP> It really is. But with the distances involved, I suppose that there
 CP> isn't another way to do it.

Actually, there's several methods for discovering exoplanets, which include:

Radial velocity - detecting the "wobble" of the star as planets orbit it.  And
they can detect multiple planets here.  This works by using Doppler shift of
the light from the star.

Direct imaging - yes, in some rare cases, it is possible!

Gravitational microlensing - seeing the effect of the planet's gravity on
distant starlight passing by.

Astrometry - Similar to radial velocity, except looking at how the position of
the host star changes as it "wobbles" with the orbiting planets, instead of
Doppler shift.

And of course, we've been discussing the transit method in this thread.

Ref:  https://exoplanets.nasa.gov/alien-worlds/ways-to-find-a-planet/#


There are other methods, but they are still fairly experimental. :)


.... But that trick never works! -Rocky
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