A new study by the US space agency NASA has revealed how moons orbiting the solar system’s outermost planet avoid colliding, even though their orbital paths overlap.

NASA’s Jet Propulsion Laboratory (JPL) recently completed a study of two of Neptune’s moons, Thalassa and Naiad, which perform what the scientists called a “dance of avoidance” as they orbit the ice giant. The two small moons orbit Neptune very close to one another, but always avoid hitting each other because they keep their distance, following a perfect pattern on a slight tilt from each other.

The paper was published in Icarus, but is also available online at arXiv.

The two Tic Tac-shaped moons are only about 60 miles across, with orbital paths only about 1,150 miles apart and with Thalassa taking about half an hour longer to complete an orbit than Naiad. However, because of their resonance pattern, every time Naiad passes through Thalassa’s orbital plane, the two moons are about 2,200 miles apart.

The study also revealed the moons are likely mostly made of ice and not rock, similarly to the dim rings around Neptune and other gas giants like Saturn.

«We are always excited to find these co-dependencies between moons,» Mark Showalter, a planetary astronomer at the SETI Institute in Mountain View, California, and a co-author of the paper, said in the press release. «Naiad and Thalassa have probably been locked together in this configuration for a very long time, because it makes their orbits more stable. They maintain the peace by never getting too close.»

A 2015 video produced by the JPL showed the Neptunian system under the watchful eye of the Kepler telescope, a space probe typically used to identify extrasolar planets.

Back in August, NASA commemorated the 30th anniversary of the Voyager 2 probe’s close pass by Neptune in 1989. Voyager 2 was the only human-made object to pass through the outer solar system, and captured the first and only up-close photographs of the deep blue ice giant and of Triton. It took the spacecraft 12 years to reach Neptune.

Sourse: sputniknews.com

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