NASA's James Webb Space Telescope has revealed a new
look at colorful auroras, but not here on Earth.
Recent observations of Neptune, the most distant planet from the Sun,
have shown a sky full of vivid cyan stretching across the planet's
upper atmosphere.
These light blue splotches, seen all around the planet, are packed
with information about how the gas giant’s atmosphere behaves.
Auroras happen when energetic particles, often originating from the sun,
become trapped in a planet's magnetic field and strike the upper atmosphere.
The energy released during these collisions creates their signature glow.
However, what has been observed in Neptune is noticeably different from what
we are accustomed to seeing here on Earth,
or even on planets closer to it, like Jupiter or Saturn.
Instead of being confined to the planet's northern and southern poles,
Neptune's auroras are located at the planet's mid-latitudes.
This is due to the strange nature of Neptune's magnetic field
that astronomers are still actively investigating.
In 1989, the Voyager II spacecraft made a flyby approach
that first confirmed Neptune's magnetic field is tilted by 47 degrees.
Since aurora activity is based where the magnetic fields converge
into the planet's atmosphere, its aurora are seen far from its rotational poles.
With this new data from Webb, the temperature at the top of Neptune's
atmosphere was measured for the first time since that flyby occurred.
And the results hint at why
these auroras have remained hidden from astronomers for so long.
Surprisingly, Neptune's upper atmosphere has cooled by several hundred degrees,
and a substantially colder temperature results in much fainter auroras
that can only be detected using Webb’s powerful scientific instruments.
This cooling also suggests that this region of its atmosphere
can change dramatically, even though the planet sits over
30 times farther from the Sun compared to Earth.
These observations were made using one of Webb's powerful onboard
scientific instruments, known as the Near-Infrared spectrograph,
and for the very first time, scientists have confirmed the presence of
trihydrogen cation, a chemical compound commonly known to be created in auroras.
These discoveries help scientists to better understand
how Neptune's magnetic field interacts with particles that stream
out from the sun to the distant reaches of our solar system.
Webb’s infrared capabilities are helping
to reveal details that have never been seen before,
opening up a window into studying ice giant atmospheres.
When Webb's observations are combined with data from
the Hubble Space Telescope and others,
the picture of what's happening on Neptune is becoming much more clear.
[ WEBB SPACE TELESCOPE ]
[ NASA ]