MAUNA KEA, HAWAII (HawaiiNewsNow) - Dark matter is one of the building blocks in the universe.
It's invisible by definition, but thanks to physics, astronomers can tell when it's there — or when it's not.
So scientists using telescopes atop Mauna Kea were shocked when they peered far out into the universe and found a galaxy (NGX1052-DF2) devoid of the stuff.
"Finding a galaxy without dark matter is unexpected because this invisible, mysterious substance is the most dominant aspect of any galaxy," said Pieter van Dokkum of Yale University, lead author of a new study of the discovery that appeared in the journal Nature.
"For decades, we thought that galaxies start their lives as blobs of dark matter. After that everything else happens: gas falls into the dark matter halos, the gas turns into stars, they slowly build up, then you end up with galaxies like the Milky Way."
But this mysterious galaxy challenges "the standard ideas of how we think galaxies form."
For the research, astronomers gathered data using the Gemini North and WM Keck Observatory atop Mauna Kea along with other telescopes around the world.
The team's calculations show that all of the mass in the galaxy they observed could be attributed to stars, which means there is almost no dark matter in it.
Why no dark matter?
Researchers have a few ideas, all unproven.
One theory: A cataclysmic event within the oddball galaxy, such as the birth of myriad massive stars, swept out all the gas and dark matter and halted star formation.