Originally taken by Hubble in 2004, today’s Astronomy Picture of the Day shows a fascinating phenomenon known as Gravitational Lensing.
Gravitational Lensing occurs when a celestial body with enough Mass bends light around its gravitational centre, this can show objects that are hidden behind others, or as in the case of the image above, can show multiple images of the same object.
Looking at the large cluster of galaxies in the centre of the image, you will notice at least 8 flattened and distorted blue images circling the outer edge, these are all one and the same galaxy and you can even make out a feint blue blob in the middle which may also be the same galaxy.
In all, recent analysis of the above image has suggested that at least 33 images of 11 separate background galaxies are discernible!
Gravitational lensing has been very useful in the past, not only giving us views of galaxies that would normally be hidden, but also in helping us locate and track Black Holes as the immense gravitation bends distant light around the centre, giving us clues over multiple timestamped images that the Black Hole is there.
You can’t see the hole, but you can clearly see what it does to the light passing nearby!