This is Scientific Americans 60 Second Science.

I'm Clara Moskowitz.

Got a minute?

Astronomers have discovered a trove of galaxies that are virtually invisible because they're made almost entirely of dark matter.

The Subaru Telescope in Hawaii spotted 854 of these oddballs, which are referred to as ultra-defuse galaxies, by detecting what little light

they do produce. They were all found in what's called the coma cluster of galaxies. The

report is in the astrophysical journal Letters.

Of course, scientists still do not know just what dark matter is,

but they can detect its presence through its gravitational effects on the normal matter that we can see.

That's how we know that dark matter that we can see.

That's how we know that dark matter seems to be ubiquitous in the universe,

especially in these newly found barely visible galaxies.

Many of these galaxies are about the size of our Milky Way, but contain just a thousandth as many stars.

Researchers estimate that dark matter accounts for 99% of these galaxies mass.

How such objects could form is a mystery. They

probably started out with a healthy complement of star forming gas, just like

normal galaxies, but somehow lost it. The gas might have blown away as the galaxies moved

through the coma cluster or maybe other galaxies gravity dragged it off. Further

study of these ultra-defuse galaxies should clarify the situation, and may even shine some light on the fundamental

nature of dark matter.

Thanks for the minute.

For Scientific American 60 Second Science, I'm Clara Moskowitz.

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