The James-Webb Space Telescope has delivered unprecedented images of the planet Neptune and its rings, which provide valuable insights into its atmosphere, NASA announcedWednesday, September 21.
Astronomers have not had such clear views of the most distant planet in the Solar System since the brief and only passage of a probe, Voyager-2, near this icy giant, in 1989. The infrared vision of the telescope offers a new way to analyze its atmosphere, explained Mark McCaughrean, adviser for science and exploration at the European Space Agency.
The telescope eliminates all glare due to the Sun's reflection off Neptune's surface and light pollution from its surroundings, so "to begin to guess the atmospheric composition" of the planet, told Agence France-Presse this astronomer who worked for more than twenty years on the James-Webb telescope project.
Seven of Neptune's fourteen moons captured
Neptune had a bluish appearance in images taken in the visible waveband by the Hubble telescope, due to the presence of methane in its atmosphere. With the James-Webb's NIRCam instrument, which works in the near infrared, the planet takes on a colorized hue in a grayish white. The picture also shows "strange light" at one of Neptune's poles, NASA said in a statement.
The telescope also captured images of seven of the planet's fourteen known moons. In particular of Triton, which resembles by its brilliance a small star. Larger than the dwarf planet Pluto, it also appears brighter than Neptune because of the reflection of sunlight off its icy surface.
Astronomers looking for planets outside the Solar System have found that those like Neptune or Uranus are the most common. “The ability to observe these closely will make it easier for others to observe them. [géantes de glace] orbiting other stars than the Sun, McCaughrean explained.
In service since July, the James-Webb Telescope is the most powerful space telescope ever deployed. It will allow a kind of astronomy "which was unthinkable even five years ago"Mr. McCaughrean said.