A massive volcanic “devil comet” hurtling toward the sun may have lost the distinctive horns that gave it its sinister name. Last week, after the comet’s last and most powerful outburst, its main ascensions did not look like those of previous outbursts. But astronomers noticed many new features of the comet, such as its rare green hue and mysterious “shadow.”

Comet 12P/Ponce-Brooks (12P) is a massive 10.5-mile-wide (17 kilometers) comet that will make its closest approach to Earth in more than 70 years next summer. Comet 12P is a cryovolcanic or cold volcanic comet consisting of an icy shell or core filled with ice and gas. When a comet absorbs enough solar radiation, its frozen interior, or cryomagma, becomes superheated. The pressure in the core increases until the shell breaks and the comet’s icy interior spills into space. Following the explosion, the comet’s coma (a cloudy, reflective cloud of cryomagma and dust) expands and the comet appears much brighter to astronomers as it reflects the sun’s rays.

12P has experienced three major explosions so far: on July 20, when it was observed to explode for the first time in 69 years; It flared up further on October 5; and on Halloween (Oct. 31), a less intense outbreak. Each time the comet blew its top, its hair morphed into an irregular shape with a “dark streak” that appeared to have a pair of horns growing out of it.

On November 14, 12P experienced another massive explosion, the most powerful to date. Astronomers watched the comet temporarily become 100 times brighter than normal over the following days as its coma expanded, Spaceweather.com reported. However, this time their characteristic horns were nowhere to be seen.

“This time the coir looks perfectly round,” Nick James, director of comets at the British Astronomical Association (BAA), told Spaceweather.com.

The comet’s horns are a result of the irregular shape of the 12P nucleus, BAA astronomer Richard Miles previously told LiveScience. According to him, the outflow of gas is probably partially blocked by a notch protruding from the core.

It is not yet known why the horns disappeared. However, frequent eruptions can destroy the notch that blocks the exit of cryomagma. During the third Halloween eruption, the horns were much less prominent than during the first two eruptions; This suggests that the notch may have already been damaged by the first two comet explosions.