#einstein cross

Microlensing of the Einstein Cross - December 15th, 1996.

TRAPPIST-1 - This is a whole star system but I'm counting them all. Absolutely magical place with seven planets around a star just barely larger than Jupiter. The entire system fits within the distance from Sol to Mercury. 3(!) of the planets are in the habitable zone, and all are roughly earth-like. They are so close to each other that you could see the other planets in their skies. It is older than our own solar system. It's just so much.

Phoenix A - The central black hole of the Phoenix Cluster. The sheer size of this thing makes me cry.

Quasi-stars (Black Hole Stars) - Does this count? They're theoretical, but whatever. Potentially the largest stars to have ever existed. Their cores would have been black holes, but maintained equilibrium between gravity and the black hole's outward radiation pressure. It's wild.

Einstein Cross - A gravitationally-lensed quasar forming a cross shape - you see the same image of it in 4 different positions due to light bending around a foreground galaxy!

The Pillars of Creation - It's a classic, but this is still one of my favourite things I've ever seen. There's something so emotional about images of this.

From SpaceTelescope.Org Picture of the Week; January 23, 2012:

Seeing Quadruple

This NASA/ESA Hubble Space Telescope picture may trick you into thinking that the galaxy in it — known as UZC J224030.2+032131 — has not one but five different nuclei. In fact, the core of the galaxy is only the faint and diffuse object seen at the center of the cross-like structure formed by the other four dots, which are images of a distant quasar located in the background of the galaxy.

The picture shows a famous cosmic mirage known as the Einstein Cross, and is a direct visual confirmation of the theory of general relativity. It is one of the best examples of the phenomenon of gravitational lensing — the bending of light by gravity as predicted by Einstein in the early 20th century. In this case, the galaxy’s powerful gravity acts as a lens that bends and amplifies the light from the quasar behind it, producing four images of the distant object.

The quasar is seen as it was around 11 billion light-years ago, in the direction of the constellation of Pegasus, while the galaxy that works as a lens is some ten times closer. The alignment between the two objects is remarkable (within 0.05 arcseconds), which is in part why such a special type of gravitational lensing is observed.

This image is likely the sharpest image of the Einstein Cross ever made, and was produced by Hubble’s Wide Field and Planetary Camera 2, and has a field of view of 26 by 26 arcseconds.

Microlensing of the Einstein Cross - July 11th, 1995.