Comment Re:Brightness (Score 2) 67
They calculated that there are 5 planets orbiting the star by the way the intensity of the star dips very, very slightly in a pattern. Are we sure there are no other mechanisms that can cause the star's intensity to vary in a pattern? We only know about our own star's sunspots, and the longer term cycle (11 years) in which the sunspots change the intensity at which it emits. How do we know that a smaller, much older star doesn't have a sunspot type cycle that is shorter or more complex, and that is what is causing this star's intensity to change?
Please refer to the Kepler FAQ
Planetary transits have durations of a few hours to less than a day. The measured solar variability on this time scale is 1 part 100,000 (10 ppm) as compared to an Earth-size transit of 1 part in 12,000 (80 ppm). Even then, most of the variability is in the UV, which is excluded from the measurements by the Kepler Mission.
Also concerning stellar variablity...
Even for the Sun - a star of low rotation rate and relatively evenly distributed active regions (in longitude) - variability is concentrated at time scales comparable to the rotational period. Fortunately, the time scales of interest to planet detection are considerably shorter.
One would hope that we can have enough faith in our friends at Nasa that they would do their homework (rather than just surf a few sites on the internet before launching a 1/2 billion dollar mission)...