Planets and Stars under the Magnifving Glass

摘要

Looking out to the vastness of the night sky, stargazers often ponder questions about the universe, many wondering if planets like ours can be found somewhere out there. But teasing out the details in astronomical data that point to a possible Earth-like planet is exceedingly difficult. To find an extrasolar planet—a planet that circles a star other than the Sun— astrophysicists have in the past searched for Doppler shifts, changes in the wavelength emitted by an object because of its motion. When an astronomical object moves toward an observer on Earth, the light it emits becomes higher in frequency and shifts to the blue end of the spectrum. When the object moves away from the observer, its light become's lower in frequency and shifts to the red end. By measuring these changes in wavelength, astrophysicists can precisely calculate how quickly objects are moving toward or away from Earth.