Orion is one of the most well-known constellations across the universe — but the mythical warrior may be missing his right shoulder before long.

The giant red star known as Betelgeuse, situated almost perpendicular to Orion’s belt, has rapidly dimmed since October. By mid-December, the once shining star, usually among the top 10 brightest stars in the sky, had plummeted out of the top 20, reported Villanova University’s Edward Guinan in an Astronomer’s Telegram.

“Now the outline of Orion is noticeably different with Betelgeuse so faint,” said Guinan.

Astronomers have pointed out that the light of Betelgeuse, what astronomers call a “semi-regular variable star,” is known for fluctuating brightness. Yet, the rapid dimming as of late is unusual, they say, prompting them to wonder if the star’s spectacular demise is approaching. The explosive death of a star, also called a supernova, would cause Betelgeuse to suddenly burn even brighter before vanishing forever.

“The biggest question now is when it will explode in a supernova,” said Sarafina Nance, a UC Berkeley astrophysics researcher, on Twitter. The 8.5 million-year-old star probably “isn’t exploding any time soon,” she added in the tweet thread, “but will be a gorgeous spectacle” when it does.

The massive Betelgeuse is 20 times the mass of our sun, and would engross Mercury, Venus, Earth, Mars, the asteroid belt and possibly even Jupiter if we were to supplant that star into our own solar system. It’s also one of the Milky Way’s closest neighbors at just 600 light-years away. But the explosion associated with the star’s demise won’t have any effect over life on Earth — aside from a good show — before fading into eternity.

Betelgeuse’s supernova “would be so incredibly cool!” Nance told National Geographic. “By far and away the most incredible thing to happen in my life.”

Unfortunately, we have no idea when the main event will go down. If the star continues to fade for another couple of weeks, “then all bets are off,” Guinan also told NatGeo. Recent studies have predicted that it will happen within the next million years, and as soon as 100,000 years from now. And there’s the possibility that it already exploded, possibly hundreds of years ago. We just haven’t waited long enough to see its impacts on the night sky.

“It’s actually quite rare to study a star this well pre-explosion, whenever that happens,” said Nance. “This will inevitably yield cool and interesting ideas for what happens to stars right before they explode.”