James Webb Telescope Captures Clear Photo of Neptune’s Rings and Moons

Neptune

NASA’s James Webb Space Telescope has captured a photo of Neptune that displays the clearest view of the planet’s rings in more than 30 years.

The space agency says that the new image crisply shows the faint rings of the distant planet, some of which have not been detected since NASA’s Voyager 2 flew by in 1989. In addition to several bright, narrow rings, the Webb image clearly shows Neptune’s fainter dust bands.

“It has been three decades since we last saw these faint, dusty rings, and this is the first time we’ve seen them in the infrared,” Heidi Hammel, a Neptune system expert and interdisciplinary scientist for Webb, says. This is because Webb’s very stable and exact image quality allows these extremely faint rings to been detected so close to Neptune,” NASA explained.

Neptune
Webb captured seven of Neptune’s 14 known moons: Galatea, Naiad, Thalassa, Despina, Proteus, Larissa, and Triton. Neptune’s large and unusual moon, Triton, dominates this Webb portrait of Neptune as a very bright point of light sporting the signature diffraction spikes seen in many of Webb’s images.

The photo was captured using the JWST’s NIRCam, or Near Infrared Camera, which captures objects from 0. 5 to 6 microns, the near-infrared range. Neptune is therefore not visible in the near-infrared range.

“In fact, the methane gas so strongly absorbs red and infrared light that the planet is quite dark at these near-infrared wavelengths, except where high-altitude clouds are present,” NASA explains. These methane-ice clouds can be seen as streaks or spots that reflect the sunlight. Images from other observatories, including the Hubble Space Telescope and the W.M. Keck Observatory, have recorded these rapidly evolving cloud features over the years.”

Neptune has a 164 year orbit around the Sun which means that the northern pole of the planet is just out of view for astronomers right now. Although the photo shows a “vortex” near the south pole, Webb’s amazing camera system has allowed astronomers to observe a band of high-latitude cloud that surrounds it.

Neptune

The photo also reveals seven of Neptune’s 14 known moons, one of which is so bright that the JWST’s iconic multi-pointed diffraction spikes make it appear as though it is a star. Triton is the correct name for it. It appears brighter than Neptune’s moons because of its frozen condensed nitrogen sheet. Because of this, the moon reflects an average of 70% of the sunlight that hits it, far outshining Neptune whose atmosphere is darkened by methane absorption at the near-infrared wavelengths.

NASA says that additional studies of Neptune and Triton with Webb are planned in the coming year despite some current mechanical issues that are affecting one of the telescope’s MIRI camera modes.


Image credits: NASA, ESA, CSA, STScI

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