Okay, skeptical hats on. Ready? Let's go.
A paper has put forward a rather unusual theory about the suspected interstellar object Oumuamua. It suggests it may not be a comet or an asteroid as thought, but instead a clump of dark matter. Mmhmm.
Oumuamua, originally known as A1/2017 U1, tore through our Solar System last month, swinging past our Sun. It had astronomers the world over giddy with excitement as evidence mounted that it was an interstellar object, perhaps originating from a star cluster 200 or so light-years away, never to return again.
There has been some debate over whether it was an asteroid or a comet. The five co-authors of this paper (available on arXiv), however, suggest that some of the unusual properties of the object point to it being composed of “macro dark matter”.
The reason they think it may be composed of dark matter is due to some of its unusual properties. For example, it had a featureless red spectrum and was described as appearing “completely stellar”. These characteristics are also consistent with it being an asteroid, of course. Occam's Razor, anyone?
“Contrary to widely held misconceptions, dark matter need not be in the form of weakly interacting elementary particles, but might instead be found in much larger pieces with masses best measured in grams or kilograms,” the team writes.
If so, they note its mass may be a whopping 10^25 grams. That’s just slightly more than the mass of Earth, despite Oumuamua measuring a paltry 0.16 kilometers (0.1 miles) across compared to Earth’s diameter of 12,727 kilometers (7,908 miles).
"We would expect that if you had one [a chunk of macro dark matter] in front of you, it would look like an extremely dense, probably very spherical, dark and maybe shiny object," Glenn Starkman from Case Western Reserve University in Ohio, one of the paper's co-authors, told IFLScience.
It might sound a bit far-fetched, but the researchers say their theory is falsifiable. That is, they can prove if it is true or not.