Artist's Conception Of An Extra Solar Planet

Well I have to say that I find it just amazing. When I was a kid, we never thought that it would be possible to detect planets outside of the solar system, they would have been just too far away. Oh there were plenty of science fiction movies about other planets, but they were mostly about Venus and Mars. Here we are now, on the cusp of something very big. It started out with a tiny whimper, a planet outside our solar system was detected. I should say the first verified exoplanet. I say this because rogue planets, those objects that are traveling in space and not part of a solar system have been discounted by scientists. In 1992 radio astronomy found a planet that orbited a *pulsar, it was orbiting 51 Pegasi. The discovery was soon verified and the first exoplanet had been found. The speed of these discoveries increased as better methods were devised and better equipment developed. As of this month, August, 2007, there have been about 240 exoplanets discovered. Exoplanets were suspected of existing in the 19th century by a few scientists, and I bet even before that. As the procedures and equipment got better, smaller and smaller planets were able to be detected. In the beginning, a planet had to be at least the size of Jupiter, or considerably bigger, to have a chance of being discovered. Today planets as small as Earth can be detected with some of the equipment that is currently in use..

The California and Carnegie Planet Search team, is responsible for the discovery of many exoplanet discoveries. In the beginning they developed a Doppler technique to detect planets, but it only was able to find giant planets. That has all changed, because of some new innovations in the design of the optics, data analysis and even the observing methods. It is now possible for them to detect Earth sized planets and they can do it using their Automated Planet Finder or APF. The Planet Finder uses a telescope at Lick Observatory. It is a fully automated 2.4 meter scope. Attached to the scope, is a very sensitive spectrometer. It is very stable. In conjunction with that, an iodine cell is employed that provides a precise wavelength scale for the Doppler analysis. The computer software will aim the scope and select the best targets, thus freeing the astronomers to conduct other duties, but still be available for a discovery. I have always said, hey if the robots want to do the job, let them.

Temperature Map Of Extra Solar Planet

The Vulcan South Photometer is another instrument that is robotic. This one is operated in the Antarctic. Much of the design work was done by the NASA Ames Research Center and the SETI institute. As most of you know out there, SETI is the Search For Extraterrestrial Intelligence. It is amazing to see, that an organization who had their funds completely cut off by the government years ago, is still around and involved with so much in this area, it is what I call a pleasant surprise. The method for planet detection is what most observatories are using today, planet transits. That is when a planet goes in front of its star, causing a slight fluctuation in the brightness of the star. The bigger the planet that passes in front of the star, the bigger the difference in light intensity. The photometer is built on a special mount that was originally created for Automated Astrophysical Site Testing Observatory (AASTO), a joint University of New South Wales (UNW) - Australian National University (ANU) - Center for Astrophysical Research in Antarctica (CARA) initiative. A photometer is merely a light intensity detection device. A special high capacity camera that contains a CCD is used. A CCD camera is a charge coupled device which enables analog signals to be picked up. It can be quite sensitive. In the old days, before this type of camera was invented, film was kept at very low temperatures to increase its sensitivity. When the astronomer wanted to use it, he put it in a 'cold camera' which took the photo. Cold cameras were pack with ice. The reason this area was chosen for planet discovery is the long winter nights.

Maybe even more incredible than the discovery of extra solar planets is that at least one of the projects to discover them has been able to detect the difference between day and night on one or more of these planets. Wow, it is incredible enough that we can discover them, but going to these lengths with our present equipment is really something. The Spitzer Observing Program is now developing techniques for detecting non transiting planets. Yep the technology just keeps getting better. When the Square Kilometer Array is finished in 2020 it will be several orders of magnitude more powerful than any radio array we now have and this should aid in picking up any signals, if they exist, from planets up to at least 1,000 light years away. If there are planets with intelligent life on them that is sufficiently advanced, we may be able to detect this. It always comes down to the same questions:
1. Will an advanced race use radio signals?
2. Will they hide their existence somehow?
3. Is it wise to broadcast our own signals out into space?

The Planetary Science Institute or PSI is also in the business of discovering extra solar planets. They are partially supported by NASA and the Planetary Society. They are also concentrating on transiting planets. The means they employ is high precision differential CCD photometry. This is the same type of search as some other organizations out there. The telescope used is the 50 inch telescope on Kitt Peak. It has been turned into a fully robotic observatory. The project collaborates with the Kepler project. The idea is to build a large database of extremely precise photometric information on many different types of stars, and candidates for extra solar planets.

Trying to search for transiting planets is only one way to look for planets. Radial Velocity searches are another way. To conduct this search you need a spectrograph , which breaks down the light from a star. What you see is sort of like a rainbow. On this rainbow are lines called absorption lines. Each line represents a different element or compound in the atmosphere of the star. If they change in time, it could be caused by a planet tugging on the star. If this happens, the lines shift in wavelength. Another type of search is the Astronomic search. This is when you look for a wobble on a star. The pull on a star from a planet causes this. This is perhaps the most difficult type of search to use. It is like trying to detect the very slight wobble caused by a ping pong ball on an object 3600 miles away.The best detection system so far seems to be the transit system and indeed it is the most popular.

This happens to be a very interesting field and we are at a time in our history where we find this even more interesting than we would after we have perfected space travel, if we ever do. Will we be thrown for a loop by planetary information that is of a nature that we least suspect right now? One never knows what we might find out, could it be something that we really didn't want to know? That is the price that one could pay for discovery. The Spanish discovered the Aztecs and just about destroyed them. What if it had worked out the other way and the Aztecs had destroyed the Spanish that landed in Mexico and then sent a fleet to Spain and destroyed that country? Now think of this on a cosmic level. Sure, I know, this is a worst case scenario, but I am just thinking out loud. Anyway, look forward to more extra solar planets being discovered as we develop better equipment that will be able to see further and further out into space.

*Pulsars are highly magnetized rotating neutron stars which emit a beam of detectable electromagnetic radiation in the form of radio waves.