 For the first time ever, astronomers have seen a distant star work the light of another star, making it seem as though it changed its position in the sky. It's a rare phenomenon known as gravitational microlensing that even Albert Einstein thought we'd never be able to see. But now that we've proven him wrong, astronomers hope to spot even more events just like this one and use them to learn more about the stars in our universe. Gravitational microlensing was first predicted as part of Einstein's theory of general relativity. And it works exactly like it sounds. It's gravity acting like a lens to manipulate the light of objects. Basically, supermassive objects such as stars and black holes actually warp space and time around them. And this warped space-time can then act like a magnifying glass, changing the path that light takes through the universe. Microlensing occurs when a star passes behind another star along our line of sight from Earth. The warping from the foreground star then amplifies the light from the background star, making it appear brighter and distorted. In fact, Einstein predicted that when two stars align, the background star would appear as a bright ring around the star in the front. We haven't seen this perfect ring from two stars outside our solar system, but this discovery is the closest thing we've ever observed. The stars weren't perfectly aligned, so we saw this weird shift in position instead. These events can only happen when stars very far apart line up just right. So that's why Einstein once wrote that, there is no hope of observing this phenomenon directly. In fact, up until now, we've only ever seen this type of movement before with our own Sun, during an eclipse in 1919. But Einstein didn't quite know how sophisticated our telescope technology would become. So in 2014, a group of astronomers using NASA's Hubble Space Telescope spotted this rare type of microlensing, when a dense white dwarf star passed in front of another star thousands of light years away. The stars weren't exactly aligned, but close enough that the white dwarf made it seem like the background star performed a little loop in the sky. Microlensing has become popular in recent decades to search for exoplanets and dark matter, since the effect can temporarily brighten distant objects that would otherwise seem dim. But now, astronomers say they can use this technique to measure the masses of stars more accurately. For this discovery, they were able to use the relative movement of that background star to figure out the mass of the white dwarf. And measuring the masses of stars this way could be much more precise than other techniques, since it involves observing the effect one star has on another. And this isn't the last time these astronomers will make measurements like this either. Now that they've figured out how to spot this type of microlensing, they're hoping to find even more events with new ground and space-based telescopes that are coming online soon. So, Einstein got it a bit wrong. We are going to be seeing a lot more of this, but you gotta give him credit for figuring all this stuff out in the first place. And this isn't the last time these astronomers will... Damn it. Astronomals. It's animals. Animal astronomers.