SETI Astronomers Accidentally Discover Tiny New Moon Orbiting Neptune

Thursday, 21 February 2019 - 11:21AM
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Thursday, 21 February 2019 - 11:21AM
SETI Astronomers Accidentally Discover Tiny New Moon Orbiting Neptune
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Screenshot: YouTube/ESA
Astronomers at the SETI Institute have discovered a previously unnoticed, city-sized moon orbiting Neptune, thanks to the Hubble telescope. According to the New York Times, the discovery was made by SETI Institute researcher Dr. Mark Showalter, who was analyzing images of Neptune's rings using a new technique when he came across a white dot that further examination proved to be what is now the 7th moon observed in interior orbit around Neptune.


Dr. Showalter and his colleagues suspect that the new moon, named Hippocamp, is likely a fragment of Proteus, the largest of Neptune's interior moons. This theory is based on images taken in 1989 by Voyager 2 that showed a massive crater on Proteus. "In 1989, we thought the crater was the end of the story," Showalter told SETI. "With Hubble, now we know that a little piece of Proteus got left behind and we see it today as Hippocamp."


Showalter and his team reported their findings in Nature, noting that Hippocamp is the tiniest of Neptune's inner moons with a mean radius of just 17 kilometers (10.56 miles). "We're basically seeing a chip off of Proteus itself," Dr. Showalter said in an interview with the Times



Hippocamp and its siblings are known as the interior moons because their orbit exists inside the orbit of Neptune's largest moon, Triton. As Showalter and his colleagues report, "along with a set of nearby rings, these moons are probably younger than Neptune itself; they formed shortly after the capture of Triton and most of them have probably been fragmented multiple times by cometary impacts."



Neptune has a total of 14 moons.
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