Albert Einstein predicted that starlight could bend and brighten when a faraway star crossed paths with a closer space body, but he never lived to see the day where it could actually happen.
That day has come for international researchers led by Kailash C. Sahu, who believes his team is the first to prove Einstein’s theory correct with the help of the Hubble Space Telescope. Einstein himself didn’t think there was any hope of proving the theory because stars are so far apart.
He was almost right, because it’s rare that the Earth, a light source and a massive object (like a galaxy) are all aligned. Early evidence stemmed from a 1919 solar eclipse when starlight was shown to have curved in what’s known as an “Einstein ring.”
The phenomenon is known as gravitational microlensing, and it could be a new tool for astronomers to find out the mass of celestial bodies, which can’t be measured very easily. The team already put it to use and calculated the mass of a white dwarf star.
It works like this: A faraway star is shining its light, but when something massive is in its way, its light bends around it to reach Earth. If the lensing is strong, light can take different paths, so on Earth we might see what look like two stars, but really it’s the same star with light coming from different paths. If the lensing is very small, it’s considered microlensing, and on Earth the only difference we might see is a brighter star.
According to the Goddard Space Flight Center, the white dwarf’s gravity bent a distant star’s light, offsetting it by about 2 milliarcseconds from its actual position. “This deviation is so small that it is equivalent to observing an ant crawl across the surface of a quarter from 1,500 miles away,” it says.
Terry Oswalt, an astronomer and chair of the Department of Physical Sciences at Embry-Riddle Aeronautical University said in a statement that white dwarf stars are fossils of past generations of stars in the Milky Way, and solving the mystery of their mass and composition opens up many doors for astronomers.
“At least 97 percent of all the stars that have ever formed in the galaxy, including the Sun, will become or already are white dwarfs — they tell us about our future, as well as our history,” Oswalt said.
Oswalt also said that teams are already on the hunt for more alignments that show gravitational lensing.
“There are a host of new surveys underway that over the next five to 10 years will be monitoring the entire sky 24/7 with high definition,” he said. “We’re bound to find a few more chance alignment of objects.”
