NASA has detected a massive thermonuclear explosion in space. The culprit appears to be a distant pulsar, according to the space agency - the remains of a star that exploded into a supernova but was too small to form a black hole.

“This burst was outstanding. We see a two-step change in brightness, which we think is caused by the ejection of separate layers from the pulsar surface, and other features that will help us decode the physics of these powerful events,” lead researcher Peter Bult, an astrophysicist at NASA’s Goddard Space Flight Center in Maryland said in a statement, Twist Article reported.

Astronomers believe the thermonuclear explosion is caused by helium, which sinks beneath the surface of the pulsar and merges into a ball of carbon. "Then the helium erupts explosively and unleashes a thermonuclear fireball across the entire pulsar surface," NICER project manager Zaven Arzoumanian explained.