"They're so rare, and they're incredibly useful scientifically," said Conor O'Riordan of the Max Planck Institute for Astrophysics.

The Dragon Arc is a smear of light across the sky that resembles a Chinese dragon, with separate images of the same distant spiral galaxy making up its head and tail. The illusion is caused by the ...

Europe’s Euclid space telescope has detected a rare halo of bright light around a nearby galaxy. The halo, known as an ...

The halo, known as an Einstein ring, encircles a galaxy 590 million light-years away, considered close by cosmic standards. A light-year is 5.8 trillion miles. Astronomers have known about this ...