Gold Barz said:
Maybe if we come up with a technique other than the wobble method which mainly focuses on Hot Jupiters wobbling their stars up we will find solar systems with their Jupiters much farther away?
Good, you're thinking like a scientist.
In fact, we are exploring (or rather, have explored) other techniques for planet detection. The first planet actually wasn't discovered by the usual radial velocity technique, but rather by timing the arrival of pulses from a pulsar (a rapidly rotating neutron star). The method is similar to the radial velocity method in that it uses the motion of the star due to the planets, but in this case we're measuring light arrival times rather than spectral shifts. This is an extremely effective technique for planet detection because we can measure the time arrival of pulses
very precisely, so much so that we were able to detect a planet of 0.015 M
earth around PSR 1257+12. That's even smaller than Mercury!
Unfortunately, pulsars are rare and these systems bear no resemblance to our own (trust me, you would not want the sun replaced by a pulsar). Another method of planet detection around normal stars is to look for eclipses (or "transits") by the planet. That is, when the planet passes in front of the star, it blocks some of the light, making the star a little bit dimmer. We can detect this dimming with our telescopes and measure how it changes with time to estimate the orbital parameters of the planet. The primary problem with this method is that it requires the planetary system to be inclined directly perpendicular to our line of sight, something that happens in only a small fraction of systems. Until recently, the only really convincing detection was a roughly Jupiter mass object around HD 209458, but the OGLE experiment has been stepping up the detection rate of late.
Also worth noting briefly is that the wobble of the host star exists in both the radial direction (as determined by spectra) and tangential directions (as determined by finding its position on the sky). The latter type of measurement requires extremely high precision "astrometry", something which we hope to achieve with SIM. This should extend the range of massive planets (gas giants, mostly) that we can detect.
What we would really like to do eventually is image the planets directly. This would allow us to compile more information, most importantly its spectrum. The primary difficulty with doing this is that the planets are usually completely obscured by the light of their host star. In the optical, typical planet-star brightness ratios are on the order of one part in a billion. There are missions being planned (most notably TPF) in which they hope to make these images by one of the two following methods:
1) Extremely high resolution imaging in the infrared. This is somewhat easier than the optical because the planet-star brightness ratio is much lower, but it's still a challenging problem that involves deploying a space interferometer.
2) Fancy optics that distort the image of the star to reveal the tiny contribution of light from the planet. This is a bit hard to explain in layman's terms, but the basic idea is that you funnel the light arriving from the central star into a different part of the detector than the light arriving from its outskirts. This may allow us to pick out the dim planet without having to resolve it separately from the star (that is, their images would be partially superimposed).
Unfortunately, such a mission is still a long ways off, so don't expect any ground-breaking detections of earth-like planets in the near future. However, the range of larger planets we can detect is ever-expanding and we should soon be able to give a better idea of how evenly distributed planets are from their host star. In addition to higher-precision instruments to detect less massive planets, we're also compiling a longer time baseline, allowing detection of planets with longer orbital periods. A planet at the size and distance of Jupiter has only just recently become detectable by even the radial velocity method.
