For the first time, scientists have spotted something wobbling around the black hole at the core of our galaxy. Their measurements suggest that this stuff — perhaps made of blobs of plasma — is spinning not far from the innermost orbit allowed by the laws of physics. If so, this affords astronomers their closest look yet at the funhouse-mirrored space-time that surrounds a black hole. And in time, additional observations will indicate whether those known laws of physics truly describe what’s going on at the edge of where space-time breaks down.
Astronomers already knew that the Milky Way hosts a central black hole, weighing some four million suns. From Earth, this black hole is a dense, tiny thing in the constellation Sagittarius, only as big on the sky as a strawberry seed in Los Angeles when viewed from New York. But interstellar gas glows as it swirls into the black hole, marking the dark heart of the galaxy with a single, faint point of infrared light in astronomical images. Astronomers call it Sagittarius A* (pronounced “A-star”).
For 15 years researchers have watched that point flicker — and wondered why. Occasionally, it flares up 30 times brighter in infrared light and then subsides, all within just a few minutes. Now, though, a team based at the Max Planck Institute for Extraterrestrial Physics in Garching, Germany, has measured not just this speck’s brightness but its position with staggering precision. When it flares, it also moves clockwise on the sky, tracing out a tiny circle, they find.
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