Thread: A question

How do you work out the size of a planet on the other side of the galaxie? Is it all guess work or is there a way to work out the size of planet that a far away?

We can't even detect planets on the other side of the galaxy. The furthest planet we've detected is only 5000 ly away. The vast majority detected are in our local neighborhood of the galaxy.

We can determine the mass of a planet by measuring the wobble it causes in its parent star. We can measure size if the planet passes in front of the star as seen by us, by noting how much it dims the star's light as it passes.

Thanks for setting me right.
And thanks for the info on how you measure the size of a star.

Originally Posted by Janus

We can measure size if the planet passes in front of the star as seen by us, by noting how much it dims the star's light as it passes.

We can do that? I have read from http://www.sciencedaily.com/releases...0610141034.htm
"The most recent observations, taken during autumn 2009, revealed the object on the other side of the disc after a period of hiding either behind or in front of the star (in which case it is hidden in the glare of the star). "

Janus, did you mean 5000 parsecs? We’ve found exo’s out to 21000 light years.
http://planetquest.jpl.nasa.gov/atla...t&SortDir=DESC


(Mole, yes we can.)