On 28 May 2009, at 07:28, JayLEads wrote:

Patrick et. al.,

Besides measuring the primary eclipse where the planet moves in front of the star, being new I am just wondering if it is possible to also do what Sptizer has done and measure the light emitted by a star alone during a secondary eclipse when the planet passes behind the star? By measuring the difference in light from when the planet moves in front of the star to when it is moving behind the star couldn't one estimate the amount of light that is coming from the planet, thus extending the graph a little more?

If I understand the linked graph it shows the light reduction from the planet coming in front of the star. So by extending it and perhaps repeating for verification of data one could determine how much light the planet is putting out and I'm sure someone could then probably make a correlation between the amount of light being put out and mass (the greater the mass the more light it would put out and/or the closer to the star in its orbit)? Perhaps I'm just loopy still from having been so sick for the last week. Back to bed and the meds.

Your approach is used when studying eclipsing binary star systems. However, as planets don't produce light but merely reflect light from their star, there would be no dimming of light from the system as the planet went behind it's parent star. Your comment does bring to mind a paper given by Jim Edwards at the recent SAS/AAVSO meeting in Big Bear. He proposed a possible optical SETI concept wherein we would be the receiver and other alien civilizations would be the transmitter. Specifically Jim suggested that were an alien civilization to send a high power laser operating at H-alpha in the direction of it's largest planets shadow as it swept the universe that if we were looking we would see an increase in brightness during the transit. And more importantly that blip in brightness at mid-transit would be recognized as an H-alpha emission and were the laser to be modulated it would be obvious that it was not a natural occurrence. He assumed that the alien intelligence and technical advancement were at the same level as our own. Further he showed that such a search for alien civilizations could be carried out by amateurs with amateur equipment. Jerry Foote ScopeCraft, Inc. 4175 E. Red Cliffs Dr. Kanab, UT 84741 435-899-1255 jfoote@scopecraft.com