Two galaxies create an eye-popping optical illusion for Hubble

When is a quasar not just a quasar? When it’s four (technically, five) views of the same quasar, of course.

Our latest Hubble image drop from NASA is a real treat. See that big shiny pool of light in the center? The one with the halo around it, and four pinpricks of light in the halo? That whole, beautiful mess is an optical illusion that’s a product of Earth’s specific position in the cosmos and the way light travels, and bends, through space.

Hubble’s eyes are playing tricks on you.
Credit: ESA/Hubble & NASA, T. Treu Acknowledgment: J. Schmidt

Let’s pull this apart. The bright center of that halo is, if you look closely, actually two bright spots that appear so close together they almost look like one. They’re two galaxies, and they only look like they’re bumping into each other because of our perspective from Earth.

The two galaxies, which NASA doesn’t identify, are also in the foreground of this image (aka they’re closer to Earth than the quasar). That’s the key to this illusion. Galaxies are extremely large celestial bodies that are held together by immense gravitational forces. When light passes through these areas, its path is warped by that pull. It’s a phenomenon called gravitational lensing.

Light traveling through space is how we see any of the space objects in the above image. So when the warped fabric of space distorts that light, it can produce some unusual effects.

A more zoomed in look at our trio of celestial bodies and the optical illusion they create.
Credit: ESA/HUBBLE & NASA, T. TREU ACKNOWLEDGMENT: J. SCHMIDT / cropping by mashable

In this case, gravitational lensing caused by the two foreground galaxies creates extra, illusory pinpricks of light in the final image. The four spots of light in the halo are all the same, single quasar, just magnified and bent around the gravitational exertions of the two galaxies. There’s also a fifth point, according to NASA, right in the dead center of that mass, that’s also another view of the same quasar.

(A quasar, short for “quasi-stellar radio source,” is an extremely distant and bright young galaxy. They’re more numerous at the edges of our visible universe.)

This image, like so many of Hubble’s best, is brought to use by Wide Field Camera 3, which was installed in 2009. The aging orbital telescope will soon have some younger, more technologically advanced company in orbit, when NASA launches the James Webb Space Telescope in October.