Astronomers have identified what's likely to be the largest black hole ever discovered.

Just how massive is it? The superlative-defying behemoth has roughly 17 billion times the mass of our own sun and consumes 59 percent of the centermost bulge of stars in its host galaxy NGC 1277. Typical black holes take up 0.1 percent of their containing galaxies, and the next biggest black hole only takes up 11 percent of its host galaxy's central bulge.

The hole in NGC 1277, located 250 million light-years from Earth in the constellation Perseus, is considered such an outlier that the scientists who discovered it took an extra year to double-check their research before submitting the results for publication.

"The first time I calculated it, I thought I must have done something wrong," lead author Remco van den Bosch tells Space.com. "We tried it again with the same instrument, then a different instrument. Then I thought, 'Maybe something else is happening.'"

And its unprecedented scale is merely the beginning. Astronomers were perplexed when they realized that the stars surrounding the black hole appear to have been "relatively undisturbed for eons," says Irene Klotz at Discovery News, meaning it wasn't gobbling up nearby stars and planets as black holes tend to do.

In other words, we may have to rethink what we know about the already mysterious relationship between black holes and their host galaxies.