Gravity is the strange, mysterious glue that holds the Universe together. But that's only one of its many charms. You can also use gravity's ability to warp space-time to see distant objects, which would otherwise be much more difficult.
This effect is known as gravitational lensing and was predicted by Einstein. It's beautifully illustrated in the Hubble Space Telescope's new release.
The image's center shows a shiny, almost-perfect ring. It has what appears to be four bright spots running along its edges, and looping around two other points with a golden glow.
(ESA/Hubble & NASA; T. Treu; Acknowledgment by J. Schmidt
This is what Einstein rings are called. The bright dots in the middle are the galaxies of three. One quasar lies behind them. As the light passes through the gravitational fields of the foreground galaxies, it becomes distorted and magnified.
The mass of the galaxies in the foreground is so large that it causes a gravitational curve of space-time around them. Any light that travels through this space time is distorted and magnified by our telescopes.
Illustration of gravitational lensesing. (NASA, ESA & L. Calada)
This is an extremely useful tool to probe both the near and far reaches of the Universe. Any object with enough mass can be used as a gravitational lens. This could be one or two galaxies as seen here or huge clusters of galaxies that produce amazing smears from light from many objects behind them.
These smears can be reconstructed by astronomers who are able to peer into deep space. They can also create replicated images that allow them to view the distant galaxies in greater detail. However, this is not all that gravitational lensing has the ability to do. The curvature and mass of the gravitational field determine the strength of a lens.
Gravitational lenses are able to allow us to weigh galaxies or clusters of galaxies. This can help us map dark matter, the mysterious source of extra gravity that cannot be explained by what we know about the Universe.
You can also use gravitational lensing (or microlensing) to locate objects in the Milky Way that are too dark to see, such as star-mass black hole.
It gets smaller. It gets smaller. Astronomers have been able to spot rogue exoplanets that are not attached from a host star. They wander the galaxy cold and alone due to the magnification caused by such exoplanets passing between us and distant stars. They've used gravitational microlensing in order to find exoplanets within other galaxies.
It is amazing to see what the Universe has up its sleeve in terms of gravitational power.
Download a wallpaper-sized version from ESA's site.
