The James Webb Space Telescope has turned its gaze away from the deep
universe towards our home Solar System, capturing an image of a luminous
Neptune and its delicate, dusty rings in detail not seen in decades,
NASA said
Wednesday.
اضافة اعلان
The last time astronomers had such a clear view of the farthest planet from
the Sun was when NASA's Voyager 2 became the first and only space probe to fly
past the ice giant for just a few hours in 1989.
Now Webb's unprecedented infrared imaging capabilities has provided a new
glimpse into Neptune's atmosphere, said Mark McCaughrean, a senior advisor for
science and exploration at the European Space Agency.
The telescope "takes all that glare and background away" so that
"we can start to tease out the atmospheric composition" of the
planet, McCaughrean, who has worked on the Webb project for more than 20 years,
told AFP.
Neptune appears as deep blue in previous images taken by the Hubble Space
Telescope due to methane in its atmosphere.
However the near-infrared wavelengths captured by Webb's primary imager
NIRCam shows the planet as a greyish white, with icy clouds streaking the
surface.
"The rings are more reflective in the infrared," McCaughrean said,
"so they're much easier to see".
The image also shows an "intriguing brightness" near the top of
Neptune, 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 had a good look
at its north pole.
Webb also spotted seven of Neptune's 14 known moons.
- Strange moon
-
Looming over Neptune in a zoomed-out image is what appears to be a very
bright spiky star, but is in fact Triton, Neptune's strange, huge moon haloed
with Webb's famed diffraction spikes.
Triton, which is larger than dwarf planet Pluto, appears brighter than
Neptune because it is covered in ice, which reflects light. Neptune meanwhile
"absorbs most of the light falling on it", McCaughrean said.
Because Triton orbits the wrong way around Neptune, it is believed to have
once been an object from the nearby Kuiper belt which was captured in the
planet's orbit.
"So it's a pretty cool to go and have a look at," said
McCaughrean.
As astronomers sweep the universe searching for other planets like our own,
they have found that ice giants such as Neptune and Uranus are the most common
in the Milky Way.
"By being able to look at these ones in great detail, we can key into
our observations of other" ice giants," McCaughrean said.
Operational since July, Webb is the most powerful space telescope ever
built, and has already unleashed a raft of unprecedented data. Scientists are
hopeful it will herald a new era of discovery.
Research based on Webb's observations of both Neptune and Triton is expected
in the next year.
"The kind of astronomy we're seeing now was unimaginable five years
ago," McCaughrean said.
"Of course, we knew that it would do this, we built it to do this, it
is exactly the machine we designed.
"But to suddenly start seeing things in these longer wavelengths, which
were impossible before... it's just absolutely remarkable."
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