planet hunting?

Question

ive just realized something about our current ways of looking for exoplanets. usually large observatories look at stars for long periods of time and wait for the planet to pass by the sun so we cant see it, and if that happens we know there is a planet there.

but think about how many flaws that has. it could be a cloudy night and you could compeltely miss it.

also, the planets have to be fairly large in comparison to their star in order for it to completely cover up the light coming from it. that means our search for an earth like planet is never going to work because all we can find are gas giants and rarely some massive solid planets.

and the biggest one. it only works if the earth, the star, and the orbit of the planet are in one plane. if their not all exactly in a line then the planet will never cross infront of the star and well never see it.

theres got to be a better way...are there any other techniques out there?

Answer 1

The primary method for locating exoplanets is to look for small periodic changes in a star's radial velocity. You do this by looking for small redshifts / blueshifts in a star's spectrum over the course of time.

Answer 2

The method you describe is only one used, and for the reasons you cite - it's not very reliable. The primary method is by watching their primary stars - if they wobble, it's probably due to gravitational influence of at least one planet. They're developing a new method of locating even smaller planets - on the order of the size of Earth - by looking at dusty/rocky planetary disks. If a shadow is cast on that disk, it *could* be from an Earth-sized planet.
Another method is to look for discoloration in a disk - which means that the star's light is being filtered through an atmosphere.
Still in the works: comparing infrared aberration and interference. A planet being heated by a star will radiate heat as it rotates, and some of the star's light will be scattered or interferred by the planet's thermal emissions - again, locating a small world.
And, the two methods we already talked about - stellar wobble and planetary transition - will be used for years as the best method of finding very large planets orbiting distant stars.

Answer 3

cbrich.........
your talking about Photometry
yes there are better ways such as
pulsar timing
radial velocity
gravitational lensing
AND looking at the planet directly
http://www.kqed.org/quest/blog/2007/03/16/planets-by-the-hundreds/

this was actually a brown dwarf, (almost a planet) but it shows that we are very close to meeting the goal.

still, the bigger the better of course

heres gliese 299b and one of its planets (still 5 times larger than earth, but it might have water)
http://www.superwasp.org/images/1995-48-a-web_print.jpg

and we have 1 more that has an UNKNOWN object, but is more than likely an exoplanet
http://archiwum.wiz.pl/images/duze/1999/05/99054202.JPG

give technology 10 more years and we should have high enough resolution to start directly viewing these types of planets regularly

Answer 4

Another technique is called Gravitational Lensing. Because gravity can "bend" the direction light travels, scientists can use this effect to locate things, like planets, that can't be seen by standard telescopes. Ways are even in use that utilize this lensing effect to focus on objects that would otherwise be unseeable.