Astronomy

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DATA

In 1964

astronomers Arno A. Penzias and Robert

W. Wilson found themselves cleaning

pigeon poop out of the Holmdel Horn Antenna, a radio telescope

in New Jersey. The data from the instrument had weird, persis-

tent noise that they couldn’t get rid of. They tried looking for

places where errant radiation signals could sneak in, and even

redesigned a part of the telescope, but the noise endured. When

nothing else seemed to work, they trapped two pigeons that had

taken up roost in the telescope and scrubbed out their droppings,

yet the noise remained. Unbeknownst to them, they were trying

to remove a fundamental signature of our universe — the cosmic

microwave background.

Just over a decade later, Wilson and Penzias won the Nobel

Prize in Physics for their serendipitous discovery of cosmic micro-

wave background (CMB) radiation. Although the pair initially had

been searching for a halo around the Milky Way, they instead

found the first light of the universe, left over from right after the

Big Bang, when photons of light were just bursting forth.

Wilson and Penzias aren’t alone in making fortuitous break-

throughs. Indeed, unexpected discoveries are almost a hallmark of

astronomy. William Herschel discovered Uranus in 1781 while

looking for binary stars, originally identifying the planet as a

In an era of large-scale surveys,

citizen science projects, and new

machine-learning techniques,

unexpected discoveries should

be expected. by Mara Johnson-Groh

Seeking the

unknown in

COSMIC