Mayank Chhaya-
Some 176 years after it was discovered in 1846, Neptune, the farthest planet in the solar system, has become visible in striking details because of the James Webb Space Telescope (JWST).
Orbiting at nearly 4.5 billion kilometers (2.78 billion miles) from the Sun, Neptune is in a deeply frozen corner of the solar system from where it takes light nearly four and a half hours to reach Earth. As NASA explains it is so far from the Sun that high noon on it is like “a dim twilight on Earth.” “The warm light we see here on our home planet is roughly 900 times as bright as sunlight on Neptune,” the agency says.
The JWST images of Neptune offer the clearest view of its rings as well as seven of Neptune’s 14 known moons: Galatea, Naiad, Thalassa, Despina, Proteus, Larissa, and Triton. “Dominating this Webb portrait of Neptune is a very bright point of light sporting the signature diffraction spikes seen in many of Webb’s images, but this is not a star. Rather, this is Neptune’s large and unusual moon, Triton.
Covered in a frozen sheen of condensed nitrogen, Triton reflects an average of 70 percent of the sunlight that hits it. It far outshines Neptune in this image because the planet’s atmosphere is darkened by methane absorption at these near-infrared wavelengths. Triton orbits Neptune in an unusual backward (retrograde) orbit, leading astronomers to speculate that this moon was originally a Kuiper belt object that was gravitationally captured by Neptune,” NASA explains.
It takes Neptune 164 Earth years to complete one orbit of the Sun. “This planet is characterized as an ice giant due to the chemical make-up of its interior. Compared to the gas giants, Jupiter and Saturn, Neptune is much richer in elements heavier than hydrogen and helium. This is readily apparent in Neptune’s signature blue appearance in Hubble Space Telescope images at visible wavelengths, caused by small amounts of gaseous methane,” NASA says.
Since the first time Neptune was seen in 1846 it has completed barely more than one orbit of the Sun. It means if a person were born on Neptune, that person would be a little over one-year-old even as 164 years would have elapsed on Earth.
At 49,500 kilometers in diameter, the ice giant is about four times (3.9 to be precise) bigger than Earth. Despite its size, it is the only planet in the solar system not visible to the naked eye.
[Above photo caption: Webb’s Near-Infrared Camera (NIRCam) images objects 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. Credits: NASA, ESA, CSA, STScI]
