From the April 2015 issue

We often read of discovering exoplanets. How far away from Earth would we be “discovered” by another civilization with our current detection technology?

Tom Connelly, Chicago
By | Published: April 27, 2015 | Last updated on May 18, 2023

Currently, the most common ways to detect exoplanets are the photometric transit technique, which seeks dips in light due to planets passing in front of their host stars, and spectroscopic ob­­servations, which detect radial velocity variations when a planet pulls on its star. Measuring radi­­al velocity shifts for Earth-sized planets with one-year orbits around Sun-like stars is not possible with current technology.

Astronomy magazine subscribers can read the full answer for free. Just make sure you’re registered with the website.