posted on Jun, 4 2013 @ 08:53 AM
Originally posted by MadMax7
There are 890 already identified planets in the Milky Way.
Whats the significance with this one ball of gas?
edit on 4-6-2013 by MadMax7 because: (no reason given)
890 may have been detected, but only a handful of those have ever been "seen" (about 5% of known exoplanets)
The first few extrasolar planets discovered back in the 1990s were discovered via the "wobble method" ("Radial Velocity method"). This method of
planet finding relied on finding stars that wobbled slightly. This wobble indicated that there are planets orbiting them. Certain physical
characteristics of the planet (size and orbit) could be determined by the amount of wobble, period and frequency of wobble, and variations in the
A later method used to find planets (and the method currently being used to find the vast majority of known planets) is the "transit method". The
Kepler Planet Finding telescope, which is in space, uses this method. The transit method relies on a planet passing directly between the line of
sight of its star and the Earth/Kepler Telescope (which is known as the planet "transiting its star"). When a planet transits its star as seen from
telescopes on Earth or from the Kepler Telescope, there is a very
slight dimming of the star as seen from the telescopes. The amount of this
dimming and frequency of dimming can give some information on the planet. The European Space agency's "CoRoT" space telescope also employs the
transit method of planet finding.
One drawback of this transit method is that the planets need to be in line with the earth in such a way that it does in fact transit its star. Even
with this limitation greatly reducing the number of planets Kepler could find using this method, Kepler has confirmed 114 planets and has a list of
almost 3,000 more candidates that are potentially planets. One reason for the 3,000 "potential" planets not being confirmed is that Kepler would
like to confirm a planet by watching it transit its star more than once.
The bottom line is that it is very, very difficult to see a planet directly, due to the relative brightness of its star compared to that of the planet
(i.e., the brightness of the star obscures the planets). Therefore, 95% of all exoplanets ever detected have never actually been seen.