Suppose you monitor a large number (many thousands) of stars over a period of 3 years, searching for planets through the transit method. Which of the following are necessary for this program to detect an extrasolar planet around one of these stars?
1. You must be able to precisely measure variations in the planet's brightness with time.
2.You must be able to precisely measure variations in the star's brightness with time.
3. As seen from Earth, the planet's orbit must be nearly face-on (perpendicular to our line-of-sight).
4. The planet must have an orbital period of more than about 3 years.
5. As seen from Earth, the planet's orbit must be seen nearly edge–on (in the plane of our line-of-sight).
6. You must repeatedly obtain spectra of the star that the planet orbits.
7. The planet must have an orbital period of less than about 1 year.
8. You must repeatedly obtain spectra of the planet itself.