Ask Ethan: What Will Our First Direct Image Of An Earth-Like Exoplanet Look Like?
“[W]hat kind of resolution can we expect? [A] few pixels only or some features visible?”
I’ve got good news and bad news. With the next generation of space-based and ground-based telescopes on the way, we’ll finally be able to image Earth-sized and super-Earth-sized planets around the nearest stars to us directly. Unfortunately, even the largest of these telescopes won’t be able to resolve these planets beyond being a single pixel (with light leaking into the adjacent pixels) in angular size. But even with that limitation, we should be able to recover signatures of continents, oceans, icecaps, clouds, atmospheric contents, water, and potentially even life.
Come find out what we will (and won’t) be able to do with our first direct images of Earth-sized exoplanets, coming to you in just a few years!
World’s Largest Telescope To Finally See Stars Without Artificial Spikes
“Compared to what we can presently see with the world’s greatest observatories, the next generation of ground-based telescopes will open up a slew of new frontiers that will peel back the veil of mystery that enshrouds the unseen Universe. In addition to planets, stars, gas, plasma, black holes, galaxies, and nebulae, we’ll be looking for objects and phenomena that we’ve never seen before. Until we look, we have no way of knowing exactly what wonders the Universe has waiting for us. Owing to the clever and innovative design of the Giant Magellan Telescope, however, the objects we’ve missed due to diffraction spikes of bright, nearby stars will suddenly be revealed. There’s a whole new Universe to be observed, and this one, unique telescope will reveal what no one else can see.”
When we take images of the Universe, we are so used to seeing the sight of spikes around the stars in our own galaxy, it frequently doesn’t even occur to us that stars are near-perfect spheres, without any spikes to them at all. These are simply image artifacts created by reflecting telescopes, since they require a secondary mirror to collect and focus the light that the primary mirror reflects. These secondary mirrors are held in place by “spider arms,” which cross the plane of the mirror and block some of the light, creating these diffraction spikes. Up until now, these spikes were unavoidable, and the best we could do was using imaging techniques to try and subtract them out. But due to a brilliant design feature, the upcoming Giant Magellan Telescope, due to be the world’s largest (for a time) at 25 meters, will be the first giant reflector to image the stars exactly as they are: without these spikes at all.
It’s an observational feat that could not only revolutionize astronomy and telescope design, but will allow us to observe faint objects near bright stars, unfettered, for the very first time.