Hubble Catches a Galaxy Cluster Making a Smiley Face
The Hubble Space Telescope just captured an amazing picture of the Universe smiling down at Earth. The image depicts a galaxy cluster called SDSS J1038+4849, and the optical effect is caused by a phenomenon called gravitational lensing, which is predicted by general relativity.
Here's the full Hubble image:
As a result of galaxies' massive gravitational force, the spacetime around a galaxy is curved, creating a gravitational field. The gravitational field then bends the light emitting from stars and galaxies, almost like an enormous lens.
In this photo, two bright, elliptical galaxies represent the eyes, while the nose is a smaller galaxy. The smile and the outline of the face are the result of gravitational lensing, as the light from more distant galaxies is being bent into an arc, one of the most common optical effects of the phenomenon.