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Fraser
2004-Jul-23, 03:11 PM
SUMMARY: Using data gathered by NASA's SORCE satellite, scientists noticed that the light from the Sun reaching the Earth decreased by 0.1% during the Venus transit earlier this year. This is similar to what happens when large sunspots obscure the face of the Sun. In October 2003, three large sunspot groups moving across the Sun dimmed it by 0.3%. These large sunspots are surrounded by bright areas called "faculae", which actually compensate for the dimmer spots, and provide a net increase in sunlight when measured over a period of a few weeks.

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chi
2004-Jul-25, 12:55 PM
So what if other stars may have have sunspots? or maybe some bigger than what we've seen on our star? doesn't that make the search for extrasolar planets a bit faulty?

antoniseb
2004-Jul-25, 01:22 PM
Originally posted by chi@Jul 25 2004, 12:55 PM
doesn't that make the search for extrasolar planets a bit faulty?
Sunspots take 13 days to cross the face of the sun, and planets take a few hours. Also sunspots tend to be somewhat variable during the course of their transits. We can measure the rotation rate of which excludes confusion with sunspots.

Further, this could only confuse the searches for planets using the transit method. Mot planets detected so far were found using the spectroscopic effect of the planet moving the star a little bit during its orbit. This also doesn't get confused by sunspots.

Most planets detected so far are roughly the size of Jupiter. It is possible for other stars to have sunspots that large, but the sun never does.

StarLab
2004-Jul-31, 05:10 AM
Let's challenge that hypothetical scenario for a bit: suppose, or imagine, that there was a Jupiter-sized planet out there about as far away from its sun as the orbit of Uranus or Neptune, and that the star was shining brightly enough for the planet to be considered in that system's "life zone." Let's assume this was a possible candidate for a life-supporting celestial body/planet. Let's assume also that at this distance, it would orbit its parent star at about the same rate as one of the farther out gassy giant planets of our own solar system...what if it took this planet 13 days to cross the surface of its sun relative to our viewpoint? How would you construct your argument if that were the case, for our purposes sake?
Let's also assume that your second paragraph were invalid for the purposes of the observation of our proposed experimental system. What effect would that have on our calculations?