APOD: 2011 December 21 - A Horseshoe Einstein Ring from Hubble
2011 December 21. A Horseshoe Einstein Ring from Hubble. Image Credit: ESA / Hubble & NASA. Explanation: What's large and blue and can wrap itself around an entire galaxy? A gravitational lens mirage. Pictured above, the gravity of a luminous red galaxy ( LRG) has gravitationally distorted the light from a much more distant blue galaxy. More ...