FYI.

This story is over 5 years old.

Tech

Newly Discovered Valley on Mercury Is Larger than the Grand Canyon

Why Mercury may have lost nine miles off its waistline over the last four billion years.
Mercury’s newly discovered valley imaged in dark blue based on observations made by NASA’s MESSENGER spacecraft. Image: NASA/JHUAPL/Carnegie Institution of Washington/DLR/Smithsonian Institution

Scientists have discovered an enormous valley on Mercury, according to new research published in Geophysical Research Letters.

Stretching for 621 miles (1,000 kilometers) across the Rembrandt impact basin in the planet's southern hemisphere, the unnamed chasm is bigger than the Grand Canyon. But unlike that natural wonder, Mercury's newly identified valley was not forged by slow riverine erosion. Rather, researchers think that the valley may be a result of the small planet literally buckling as it contracts into an ever-smaller ball.

Advertisement

"Mercury's great valley is […] the result of the global contraction of a shrinking one-plate planet," Tom Watters, senior scientist at the Smithsonian National Air and Space Museum and lead author of the new research, commented in a statement.

READ MORE: The First Spacecraft To Orbit Mercury Will Die Today, Alone

Scientists have long suspected that Mercury is "an incredible shrinking planet," to quote NASA. Decades of research and exploration have revealed that this tiny world, which is only about 1.4 times larger than the Moon, is dominated by a dense core that takes up about 85 percent of the planet's radius (in comparison, Earth's core layers only extend to about 50 percent of the radius).

Video animation of Mercury's new valley. Video: NASA/JHUAPL/Carnegie Institution of Washington/DLR/YouTube

Since its fiery inception in the infant solar system, Mercury's core has been steadily cooling off and thus contracting, which has caused the entire planet to shrink. Because Mercury's innards are sealed within a single plate of lithosphere, this shrivelling effect has caused its surface to warp along fault lines. According to Watters and his team, this is the most likely explanation for the creation of the giant valley and the massive scarps that flank it.

Indeed, observations from NASA's MESSENGER orbiter suggest that Mercury is nearly nine miles shorter in diameter than it was four billion years ago. No wonder it has ended up with such gnarly surface features. Like a pumpkin left out too long after Halloween, our solar system's innermost planet is falling in on itself as its core gradually collapses, leaving its warped remains for all to see.

Get six of our favorite Motherboard stories every day by signing up for our newsletter.