This intriguing observation from the Hubble Space Telescope reveals a gravitationally lensed galaxy with the long-winded identifier SGAS J143845+145407. Gravitational lensing has generated a mirror image of the galaxy at the center of this image, creating a captivating centerpiece.
Gravitational lensing occurs when a very massive celestial body — such as a galaxy cluster — causes a sufficient curvature of spacetime to bend the course of light around it, as if by a lens. Appropriately, the body causing the light to curve is called a gravitational lens, and the distorted background object is referred to as being “lensed.”
Sometimes, gravitational lensing can result in multiple images of the original object, as seen with the galaxy in this image, or in the background object appearing as a distorted arc or even a ring. Another significant effect of this lensing distortion is magnification, which allows astronomers to view objects that would otherwise be too far away or too faint to be seen.
The NASA/ESA Hubble SPace Telescope has a special flair for detecting lensed galaxies. The telescope’s sensitivity and crystal-clear vision allow it to see very faint and distant gravitational lenses that cannot be detected with ground-based telescopes because of the blurring effect of Earth’s atmosphere. In fact, Hubble was the first telescope to resolve details within lensed images of galaxies, and is capable of imaging both their shape and internal structure.
This particular lensed galaxy image is from a set of Hubble observations that take advantage of gravitational lensing to peer inside galaxies in the early Universe. The lensing reveals details of distant galaxies that would otherwise be unobtainable, and this allows astronomers to determine star formation in early galaxies. This in turn gives scientists a better insight into how the overall evolution of galaxies has unfolded.