Hubble Image of the Week – A Smiling Lens

The galaxy cluster SDSS J1038+4849 appears to be smiling, with two bright galaxies resembling orange eyes and a white button nose. However, this “happy face” is an illusion caused by strong gravitational lensing, where the arcs create the misleading smile lines. Credit: NASA & ESA; Acknowledgement: Judy Schmidt

This newly released Hubble image shows galaxy cluster SDSS J1038+4849.

In the center of this image, taken with the NASA/ESA Hubble Space Telescope, is the galaxy cluster SDSS J1038+4849 — and it seems to be smiling.

You can make out its two orange eyes and white button nose. In the case of this “happy face”, the two eyes are very bright galaxies and the misleading smile lines are actually arcs caused by an effect known as strong gravitational lensing.

Galaxy clusters are the most massive structures in the Universe and exert such a powerful gravitational pull that they warp the spacetime around them and act as cosmic lenses which can magnify, distort, and bend the light behind them. This phenomenon, crucial to many of Hubble’s discoveries, can be explained by Einstein’s theory of general relativity.

In this special case of gravitational lensing, a ring — known as an Einstein Ring — is produced from this bending of light, a consequence of the exact and symmetrical alignment of the source, lens, and observer resulting in the ring-like structure we see here.

Hubble has provided astronomers with the tools to probe these massive galaxies and model their lensing effects, allowing us to peer further into the early Universe than ever before. This object was studied by Hubble’s Wide Field and Planetary Camera 2 (WFPC2) and Wide Field Camera 3 (WFC3) as part of a survey of strong lenses.

A version of this image was entered into the Hubble’s Hidden Treasures image processing competition by contestant Judy Schmidt.