This depiction of an Earth-like exoplanet showcases a rocky world with a thin atmosphere in its parent star’s habitable zone. It has oceans and continents and clouds, and could possess macroscopic life forms on its surface. At a distance of multiple light-years away, it would take a gargantuan telescope to image them. (Credit: NASA Ames/JPL-Caltech/T. Pyle)

Ask Ethan: Could a big enough telescope see aliens directly?

If there are human-sized creatures walking around on other planets, would we be able to view them directly?

There are, at present, three main avenues (and one fringe avenue) by which scientists are searching for life beyond Earth. The first is within our Solar System: by sending orbiters, landers, rovers, and fly-by spacecraft to other worlds that could harbor life. The second is by examining the exoplanets we’ve discovered from afar, hoping to find biosignatures or at least bio-hints. And the third is by searching for technosignatures: unnatural signals that offer evidence that they were created by an intelligent being. On the fringes, some even search for evidence that aliens are already here on Earth, although its scientific merits are largely disputed.

But what if we had strong suspicions that there actually were not only aliens, but human-sized aliens walking around on the surfaces of other worlds? Would it be possible to image them directly? That’s what Shawn Harvey wants to know, asking:

“If we built a telescope large enough could we see if there are people walking around on other planets?”

There are, no doubt, some barriers and strong caveats to this question, but the short answer is…