The James Webb Space Telescope has turned its gaze from the deep Universe to our native solar system, capturing an image of a glowing Neptune and its faint, dusty rings not seen in decades, NASA said Wednesday.
The last time astronomers had such a clear view of the furthest planet from the Sun was when NASA’s Voyager 2 spacecraft became the first and only spacecraft to fly by the ice giant for just a few hours in 1989.
Now, Webb’s unprecedented infrared imaging skills have provided a new insight into Neptune’s atmosphere, said Mark McCaughrean, a senior adviser on science and exploration at the European Space Agency.
The telescope “takes away all that glare and background” so that “we can start teasing out the planet’s atmospheric composition,” McCaughrean, who has worked on the Webb project for more than 20 years, told AFP.
Neptune appears deep blue in earlier images taken by the Hubble Space Telescope due to methane in its atmosphere.
However, near-infrared wavelengths captured by Webb’s primary imager, NIRCam, show the planet a greyish white, with icy clouds criss-crossing the surface.
“The rings are more reflective in the infrared,” McCaughrean said, “so they’re much easier to see.”
The image also shows “intriguing brightness” near Neptune’s apex, NASA said in a statement. Because the planet is tilted away from Earth and takes 164 years to orbit the sun, astronomers have not yet looked closely at its north pole.
Webb also discovered seven of Neptune’s 14 known moons.
– Strange Moon –
A very bright, spiky star looms over Neptune in a reduced image, but it is actually Triton, Neptune’s strange, huge moon surrounded by Webb’s famous diffractive peaks.
Triton, which is larger than the dwarf planet Pluto, appears brighter than Neptune because it’s covered in ice that reflects the light. Neptune, on the other hand, “absorbs most of the light that falls on it,” McCaughrean said.
Because Triton wrongly orbits Neptune, it is believed that it was once an object from the nearby Kuiper Belt that was captured in the planet’s orbit.
“So it’s pretty cool to watch,” McCaughrean said.
As astronomers scour the universe in search of other planets like ours, they’ve found that ice giants like Neptune and Uranus are the most common in the Milky Way.
“By being able to look at these in great detail, we can incorporate our observations of other ‘ice giants,'” McCaughrean said.
In operation since July, Webb is the most powerful space telescope ever built and has already uncovered a series of unprecedented data. Scientists hope it will usher in a new era of discovery.
Research based on Webb’s observations of Neptune and Triton is expected over the next year.
“The kind of astronomy we’re seeing now was unimaginable five years ago,” McCaughrean said.
“Of course we knew it would do that, we built it to do that, it’s the very machine we designed.
“But suddenly being able to see things at these longer wavelengths that were previously impossible… it’s just absolutely remarkable.”