Question

Which of the following pieces of information CAN be obtained from an observation of an exoplanet using the transit method but CANNOT be obtained using the radial velocity method?

a) An absorption spectrum from the planet's atmosphere
b) The planet's orbital period
c) An estimate of the planet's mass
d) The length of the planet's orbital semimajor axis
e) Whether or not the planet is in the habitable zone of its parent star

Answer 1

The transit method can obtain an absorption spectrum from a planet's atmosphere, which is not possible with the radial velocity method.

Step-by-step explanation:

The piece of information that can be obtained from an observation of an exoplanet using the transit method but cannot be obtained using the radial velocity method is: a) An absorption spectrum from the planet's atmosphere. The transit method involves the observation of a planet as it passes in front of its host star, resulting in a slight dimming of the star's brightness. During this transit, some of the starlight passes through the planet's atmosphere, and by analyzing the resulting absorption spectrum, scientists can glean information about the atmospheric composition of the exoplanet. This is not possible with the radial velocity method, which focuses on detecting variations in the star's radial velocity to estimate a planet's mass and orbital period from the gravitational pull it exerts on the star.