Discover - USA (2020-01 & 2020-02)

72 DISCOVERMAGAZINE.COM

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Reading

Minds,

Aloud

BY JONATHON KEATS

38

i

Mars, it now seems, was once a very wet world.

A new global study of ancient riverbeds on the Red Planet shows

they’re wider than Earth rivers, on average, and once carried large

volumes of water across the planet. Scientists were surprised to find they

also flowed recently, perhaps within the past billion years.

That’s well after astronomers think Mars began losing its atmosphere to

space, causing the world to dry out. It’s not clear how a planet with minimal

sunlight and a slight atmosphere stayed warm enough to host even a little

surface water — let alone fast-flowing rivers.

The findings appeared in March in the journal Science Advances.

Lead author Edwin Kite of the University of Chicago says that if the data are

correct, something else in our comprehension of the planet must be wrong.

Maybe the rivers are older than researchers think. Or perhaps Mars dried

out much faster than current theories suggest. Or, Kite says, some unknown

process also may have kept Mars warm long enough for large rivers to flow,

even after most of its atmosphere had disappeared.

“All three options are uncomfortable,” Kite says. “All three of these solutions

would require significant revision of our current understanding.”

The Mystery of

Mars’ Raging

Rivers

BY KOREY HAYNES

37

In this false-color image of an ancient martian

riverbed, blue indicates lower elevation and

yellow indicates higher elevation.