NASA has released beautiful photos taken by the NASA/ESA/CSA James Webb Space Telescope of the ice giant Neptune, its dusty rings, and seven moons.
Located 30 times farther from the Sun than Earth, Neptune orbits in the remote, dark region of the outer Solar System.
At that extreme distance, the Sun is so small and faint that high noon on this giant planet is similar to a dim twilight on Earth.
Neptune is the only planet in the Solar System not visible to the naked eye and the first predicted by mathematics before its discovery.
In 2011, the massive planet completed its first 165-year orbit since its discovery in 1846.
Neptune is characterized as an ice giant due to the chemical make-up of its interior.
Compared to gas giants Jupiter and Saturn, it is much richer in elements heavier than hydrogen and helium.
This is readily apparent in Neptune’s signature blue appearance in visible-light images from the NASA/ESA Hubble Space Telescope, caused by small amounts of gaseous methane.
NASA’s Voyager 2 is the only spacecraft to have visited Neptune up close. It flew past in 1989 on its way out of the Solar System.
“It has been three decades since we last saw Neptune’s faint, dusty rings, and this is the first time we’ve seen them in the infrared,” said Dr. Heidi Hammel, a Neptune system expert and interdisciplinary scientist for Webb.
“Webb’s extremely stable and precise image quality permits these very faint rings to be detected so close to Neptune.”
Webb’s Near-Infrared Camera (NIRCam) observes in the near-infrared range from 0.6 to 5 microns, so Neptune does not appear blue to Webb.
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.
Such methane-ice clouds are prominent as bright streaks and spots, which reflect sunlight before it is absorbed by methane gas.
More subtly, a thin line of brightness circling the planet’s equator could be a visual signature of global atmospheric circulation that powers Neptune’s winds and storms.
The atmosphere descends and warms at the equator, and thus glows at infrared wavelengths more than the surrounding, cooler gases.
Neptune’s 164-year orbit means its northern pole, at the top of this image, is just out of view for astronomers, but the Webb images hint at an intriguing brightness in that area.
A previously-known vortex at the southern pole is evident in Webb’s view, but for the first time the space telescope has revealed a continuous band of high-latitude clouds surrounding it.
Webb also captured seven of Neptune’s 14 known moons, including its large and unusual moon Triton.
Covered in a frozen sheen of condensed nitrogen, Triton reflects an average of 70% of the sunlight that hits it.
It far outshines Neptune because the planet’s atmosphere is darkened by methane absorption at these near-infrared wavelengths.
Source link: https://www.sci.news/astronomy/webb-neptune-11218.html