Yousuf Khan wrote:
On 17/10/2012 2:20 PM, wrote:
I'd like to know why they have just found a planet at Alpha Centauri,
our nearest star, when they have been searching the skies for years
and have found 600 or so planets (iirc). it must've been the first
place they looked, mustn't it? Strikes me as odd.

Most of the 1000's of exoplanets found so far have been discovered by
Kepler. Kepler only looks for planets by the Transit Method, which
when you get right down to it, is the easiest method of detecting
planets. Before Kepler, we used the Wobble Method. The Wobble Method
uses Doppler shifts to determine if a planet is tugging on a star. It
works really well when the planets are really massive and/or very
close in to their stars. Smaller planets are harder to detect using
this method. We couldn't use the Transit Method like with Kepler
because this star system doesn't seem to be aligned to our line of
sight. Also Kepler probably doesn't even point in the direction of
this star system.

True, Kepler is scanning only a small portion of the sky in the northern
Milky Way, in (IIRC) Cygnus.


So our only hope was to find a planet with the Wobble method, which
as I said before, is better at detecting Big planets. But they've
refined the Wobble Method, and it can detect far smaller planets now.
It's much harder to detect planets with the Wobble method, but it can
detect planets that aren't perfectly aligned with our line of sight.

Yousuf Khan

--
Mike Dworetsky

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