Question

which of the following describes the transit method for detecting an exoplanet?
a using powerful telescopes to directly photograph light from the planet orbiting another star
b detecting the drop in a stars brightness as a planet passes in front of it
c analyzing changes in a stars spectrum caused by the doppler shift
d observing the wobble of a star caused by the gravitational pull of an orbiting planet

Explanation:

The transit method for detecting exoplanets relies on observing the periodic dimming of a star's light as an exoplanet passes (transits) in front of it. This is a photometric method where the decrease in brightness (transit depth) can give information about the planet's size relative to the star.

• Option A describes direct imaging, which is a different exoplanet detection method.
• Option C refers to the radial - velocity (Doppler) method.
• Option D is related to the astrometric method (detecting stellar wobble).

Answer:

B. Detecting the drop in a star's brightness as a planet passes in front of it