Hubble Photo of the week

Let’s not forget the Hubble Space Telescope, now overshadowed by the Webb. Yet the Hubble site, run by NASA and the ESA (European Space Agency) still issues a weekly photo. Here’s this week’s, called “Lens Flair“.  Look at that mirror image galaxy!

Part of the description:

This intriguing observation from the NASA/ESA Hubble Space Telescope shows a gravitationally lensed galaxy with the long-winded identification SGAS J143845+145407. Gravitational lensing has resulted in a mirror image of the galaxy at the centre of this image, creating a captivating centrepiece.

Gravitational lensing occurs when a massive celestial body — such as a galaxy cluster — causes a sufficient curvature of spacetime for the path of light around it to be visibly bent, 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”. Gravitational lensing can result in multiple images of the original galaxy, as seen in this image, or in the background object appearing as a distorted arc or even a ring. Another important consequence of this lensing distortion is magnification, allowing astronomers to observe objects that would otherwise be too far away or too faint to be seen. . .

. . . This particular lensed galaxy 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.

Gravitational lensing, caused by the curvature of spacetime by gravity, causes light to bend. This was predicted by Einstein’s theory of relativity, and that theory is visually confirmed by images like this. (It also constituted the first test of general relativity by Eddington and his collaborators in 1919.