Albert Einstein first predicted gravitational microlensing almost one hundred years ago. He stated that if two stars in space lined up precisely with Earth, the one farthest away would appear as a ring around the second star because of the effect its gravity had on light.
If they were not perfectly aligned, the gravity would seem to move the star’s position. While a version of this effect was observed in stars aligned with our own sun, it has been witnessed, for the first time ever, in deep space as Einstein imagined.
Gravitational Microlensing Spotted Against Expectations
One of the core parts of Einstein’s Theory of Relativity is that the gravity of large astral bodies can warp spacetime and bend light. This means that the light coming from far away objects is affected by the bodies it passes. It distorts the path of the light, creating an optical illusion that appears to change the background star’s position. It is only when they are in perfect alignment that an “Einstein Ring” would appear.
Technically, this phenomenon was observed for the first time in 1919. At the time, during a solar eclipse, astronomers noted that certain background stars had distorted positions from behind the Sun.
This pleased Einstein, but he wrote in 1936, regarding the distant star scenario, that “there is no hope of observing this phenomenon directly.” His concerns came from the odds of two distant stars and an observational point on Earth coming into perfect alignment.
However, a group of astronomers has been using the Hubble Telescope to search for this perfect positioning and have at last found an “asymmetric Einstein Ring”. One where the stars are not perfect in alignment, but close enough to create a distorted Einstein Ring of light. They can now use this measurement to determine the mass of the star, due to its gravitational microlensing effect.
A study paper with the most recent information about the phenomenon and its application is available in the journal Science.
Image Source: JPL/NASA