James Webb space telescope discovers auroras on Neptune
The James Webb Space Telescope has photographed auroras on Neptune for the first time. These are only faint and occur in an unusual place.
Northern lights on Neptune
(Image: NASA, ESA, CSA, STScI, Heidi Hammel (AURA), Henrik Melin (Northumbria University), Leigh Fletcher (University of Leicester), Stefanie Milam (NASA-GSFC))
When charged particles from the sun hit the Earth's magnetic field, the atmosphere lights up with color. The aurora, which occurs on Earth mainly in the high latitudes, is not limited to our planet.
The James Webb Space Telescope (JWST) has recorded auroras on the planet Neptune for the first time. The images were taken in June 2023 with the telescope's near-infrared spectrograph, the JWST team announced to the European Space Agency ESA. Previously, there was only evidence of the atmospheric phenomenon on Neptune. JWST has now provided proof of this, as the team reports in the scientific journal Nature Astronomy.
In addition to the image of the aurora, JWST provided a spectrum that enabled the astronomers to determine the composition and temperature of the planet's upper atmosphere, the ionosphere. For the first time, they discovered an extremely conspicuous emission line that indicates the presence of protonated hydrogen or trihydrogenium cations (H3+), which can be produced in auroras.
Neptune's auroras at mid-latitudes
In addition to Earth, astronomers have detected auroras on Jupiter, Saturn and Uranus. However, according to the researchers, the auroras on Neptune are very different from those on these planets. On Neptune, they mainly occur in mid-latitudes –, roughly where South America is located on Earth, writes the ESA.
The reason for this is the planet's strange magnetic field. It is inclined by 47 degrees to the planet's axis of rotation. Auroras occur where the magnetic fields in a planet's atmosphere converge. In the case of Neptune, this is not at its rotational poles, but in the mid-latitudes.
Neptune's strange magnetic field was discovered by the Voyager 2 space probe in 1989. The data collected by JWST will contribute to a better understanding of Neptune's magnetic field.
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The reason why the Neptunian auroras have not been discovered for so long is that they only glow faintly. The reason for this is the low temperature in the upper atmosphere. Voyager measured the temperature in Neptune's ionosphere for the first time. It is the first measurement of its kind since then.
(wpl)
