By Seth Borenstein
The newly pictured supermassive black hole is a beast with no name, at least not an official one. And what happens next could be cosmically confusing.
The team of astronomers who created the image of the black hole called it M87(asterisk). (The asterisk is silent.) A language professor has given it a name from a Hawaiian chant - Powehi - meaning "the adorned fathomless dark creation." And the international group in charge of handing out astronomical names? It has never named a black hole.
The black hole in question is about 53 million light years away in the centre of a galaxy called Messier 87, or M87 for short. On Wednesday, scientists revealed a picture they took of it using eight radio telescopes, the first time humans had actually seen one of the dense celestial objects that suck up everything around them, even light.
The International Astronomical Union usually takes care of names, but only for stuff inside our solar system and stars outside it. It doesn't have a committee set up to handle other objects, like black holes, galaxies or nebulas.
The last time there was a similar situation, poor Pluto somehow got demoted to a dwarf planet, leading to public outcry, said Williams College astronomer Jay Pasachoff, a star-naming committee member.
Technically, our own galaxy - the Milky Way - has never been officially named by the IAU, said Rick Fienberg, an astronomer and press officer for the American Astronomical Society. He said, "that's just a term that came down through history."
"Virtually every object in the sky has more than one designation," Mr Fienberg said. "The constellations have their official IAU sanctioned names but in other cultures, they have other names."
The gift of a name
When it comes to the black hole we saw this week , University of Hawaii-Hilo Hawaiian professor Larry Kimura stepped up even before the photo was unveiled.
Powehi (pronounced poh-veh-hee) is the black hole's Hawaiian name, not its official name, explained Jessica Dempsey, who helped capture the black hole image as deputy director of the James Clerk Maxwell Telescope on Mauna Kea, Hawaii's tallest mountain. Hawaii Governor David Ige proclaimed 10 April as Powehi day, she said.
"This isn't astronomers naming this," she said. "This is coming from a cultural expert and language expert. This is him coming to the table and giving us a gift of this name. It's a gift from Hawaiian culture and history, not the other way around."
When asked about Mr Kimura's idea, IAU naming committee member Mr Pasachoff said: "That's the first I heard of it."
Eric Mamajek, chairman of the IAU working group on star names, called it a "wonderful, thoughtful name."
The pluto situation
But Mr Mamajek said his committee may not be the right one to grant the black hole a name. It only does stars.
"This is exactly the Pluto situation," Mr Pasachoff said.
In 2006, astronomers at the IAU were discussing naming a large object in our solar system that eventually got called Eris. It wasn't considered a planet, so it wasn't the job of the planet committee. But some experts pointed out that it was bigger than Pluto, which added some confusion.
The conference decided to reclassify planets, kicked Pluto out of the club of regular planets and made it join the newly established dwarf planets category with Eris, Mr Pasachoff said.
More names coming
The same day the photograph of the black hole was unveiled, the IAU asked the public to choose between three names for an object astronomers call 2007 OR10. It's an icy planetesimal that circles the sun but gets 100 times further from our star than Earth does.
The three proposed names are Gonggong, a Chinese water god with red hair and a serpent tail; Holle, a European winter goddess of fertility; and Vili, a Nordic deity and brother of Odin.
The IAU is trying to bring in more languages and cultures into the naming game, Mr Pasachoff and Mr Fienberg said. And soon the IAU will ask the public to help name 100 planets outside our solar system.
As astronomers gaze further into the cosmos, Mr Pasachoff said, "we will need more names."