We're homing in on the blobs from outer space.
In the past three decades astronomers have seen dips in the radio signals from quasars and pulsars, seemingly caused by a dark object passing by. These events don't all look the same, so it isn't clear if they share a cause. Sometimes different radio frequencies are delayed by different amounts, while other times the radio signal twinkles.
Now new observations are giving us a clearer picture. Bill Coles of the University of California, San Diego, and his colleagues used the Parkes Pulsar Timing Array, which carefully measures pulsar signals in an attempt to detect gravitational waves. The team used it to look for radio waves held up by a passing blob.
Violently turbulent clouds
They saw both time delays and twinkles from pulsars at the same time. That suggests the different phenomena may be coming from the same thing – violently turbulent clouds.
"This is an interstellar cloud way out in the middle of nowhere," Coles says. "It makes a person wonder – what the hell is that out there?"
