Question

1. how did astronomers first discover a planet revolving around another star?

Explanation:

Astronomers first discovered a planet revolving around another star by observing the gravitational effect of the planet on its host star. When a planet orbits a star, it causes the star to wobble slightly. By measuring these small wobbles using Doppler spectroscopy, astronomers can detect the presence of an orbiting planet.

Answer:

Astronomers first discovered a planet revolving around another star by observing the gravitational effect of the planet on its host star. When a planet orbits a star, it causes the star to wobble slightly. By measuring these small wobbles using Doppler spectroscopy, astronomers can detect the presence of an orbiting planet.