As Albert Einstein published his Theory of General Relativity, part of what it contained was an explanation of how gravity could bend the path of light. A very concrete proof of this, Einstein predicted, would be if two stars lined up perfectly with the planet Earth.
The light from the farther star would not be blocked by the nearer. Rather, it would be affected by gravitational microlensing, a warping effect that would cause the light to bend around the closer star.
Einstein himself claimed that we would probably never witness this phenomenon, but scientists watched the path of over 5,000 stars to finally glimpse the perfect moment.
The Effects of Gravitational Microlensing: “Einstein Rings”
The effect created by a perfect alignment of this phenomenon is referred to as an “Einstein Ring”. In it, the light of the hindmost star appears as a ring around the nearer because of the gravitational microlensing.
When the effect is out of alignment, it can distort the position of the rear star. This was first seen around our own sun during a total solar eclipse in 1919. The light from distant stars bent slightly as it passed around our sun, causing their positions to seemingly change. However, it has never before been detected in two deep space stars, until now.
What scientists are calling an “asymmetric Einstein Ring” appeared when two stars in deep space aligned near perfectly with the Hubble telescope. Much as Einstein predicted, the light from the more distant star bent around the closer one, forming an asymmetric ring.
A fascinating practical use of this lensing is to weigh the mass of stars. This is something never done before. The astronomers were able to measure the level at which the light bent. They managed to do so by determining the mass of the gravitational body present.
Scientists continue the search, as more observations of this effect could lead to untold secrets. A research paper describing the spotted phenomenon is available in the journal Science.
Image Source: JPL/NASA