NASA's Voyager 2 Witnesses Neptune's Intriguing 'Northern Triangle'

Neptune's northern hemisphere recently revealed a new mysterious feature in its atmosphere, which has left scientists debating on its cause and implications.

NASA's Voyager 2, which flew by Neptune in 1989, captured images of a dramatic spike in speed and size of the planet's winds, forming what scientists have dubbed the "Northern Triangle." This newly discovered feature contradicts predictions of slower, symmetric winds around the north pole and begs the question: why now?

Scientists speculate the "Northern Triangle" is a result of a massive atmospheric storm, racking up speed and momentum over thousands of miles. Unlike Jupiter's famous Great Red Spot, this atmospheric storm is symmetrical, stretching across a span of 20 degrees in latitude.

"We knew from previous observations that wind speeds would increase with latitude in Neptune's northern hemisphere, but we didn't know how dramatic the increase would be," says Dr. Andy Dedrick, a planetary scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, who led the research. "The increase in wind speed, or differential rotation, is much more pronounced than we expected. We're wondering if this is something transient, or if it's a new normal."

Dedrick presented the discovery on Monday, January 23 at the American Astronomical Society's Division for Planetary Science 48th Annual Meeting in Arlington, Virginia.

The feature was observed through images taken with Voyager 2's narrow angle camera, which gathered precious data on Neptune's atmosphere during the spacecraft's historic flyby. However, it wasn't until recent years that scientists had the chance to thoroughly analyze the images, with the help of modern imaging techniques.

To their surprise, they discovered the fastest winds on the planet, blowing up to 1,500 miles per hour (2,400 kilometers per hour), were confined to a large area spanning Neptune's northern pole, resembling a triangle. According to their findings, the feature likely formed in the 1990s and hangs around to this day.

"We don't know what caused this feature," says Glenn Orton, a planetary astronomer at NASA's Jet Propulsion Laboratory in Southern California. "But we know these speeds are unprecedented since Voyager 2's flyby of Neptune."

As the feature's existence contradicts current models of Neptune's atmosphere, scientists are compelled to running computer simulations of the planet's winds, to hopefully paint a clearer picture of the "Northern Triangle's" origins and impact on the planet. The findings could also reveal more on the underlying dynamics of Neptune's atmosphere.

"Every time we've studied Neptune using remote sensing, the results have been surprising and unexpected," Dedrick says. "And each time, the planet reminds us how little we understand about it."

While both Voyager 2 and the Hubble Space Telescope have captured valuable data on the feature, scientists agree that an orbiter is needed to continue studying the phenomenon. NASA is considering an orbiter mission to Neptune's tropical storm activity, which, if selected, could launch in the 2030s.

In the meantime, scientists will continue to analyze the data at their disposal to further understanding of the "Northern Triangle" and its implications for Neptune's mysterious northern hemisphere.

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