We're honing 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.