2023-07-23 10:04:13
Madrid
Updated Sunday, July 23, 2023 – 10:04
The James Webb Space Telescope Captures Stunning Infrared Images of the Giant Ringed Planet
Infrared image of Saturn captured by WebbNASA/ESA/CSA/JWST/Tiscareno et al.
The astronomer Rafael Bachiller reveals to us in this series the most spectacular phenomena of the Cosmos. Topics of throbbing research, astronomical adventures and scientific news about the Universe analyzed in depth.
the space telescope James Webb has captured an image of Saturn in the infrared that shows us an unknown and surprising facet of the giant of the rings.
upper atmosphere
Among the many tasks that have been entrusted to the Webb telescope are observations of the planets in our solar system. When working in the infraredthis telescope has already offered us unusual images, for example, of Jupiter with its auroras and of uranus with its rings. Now it is Saturn’s turn.
The image that has recently been made public has been taken in a monochromatic infrared filter centered at 3.23 microns of wavelength, characteristic of methane. The planet’s disk appears quite dark, indicating a high methane content in the upper atmosphere, a compound that absorbs this wavelength of light that the planet is receiving from the Sun.
The northern hemisphere of the planet appears somewhat brighter than the southern hemisphere due to the seasonal differences you might expect: it is summer in the north, while the southern hemisphere is late winter. However, a deep darkness is observed at the north pole that is not known to what it is due.
A clear brightening towards the limb is also observed, suggesting that, at very high altitudes, methane not only absorbs light, but also emits some radiation, very possibly due to a fluorescence phenomenon (re-emitted light after absorption).
What this infrared image does not show are the characteristic horizontal bands that are visible that are familiar to us in photographs taken in the optical domain. Such bands follow the lines of constant latitude of the planet and are due to cloudy areas in deep layers of the atmosphere.
rings
In the infrared image, lSaturn’s icy rings appear very bright, confirming that they do not have methane in their composition. The strong contrast between the rings and the dark disk is what gives the Webb image its unusual appearance. Saturn has ten known rings, and in this image it is possible to see fine details in the three main ones of the system (A, B and C). These three rings total a width of 275,000 kilometers (equivalent to three quarters of the Earth-Moon distance), the F ring is much thinner and paler, but it can also be seen very clearly in the new image.
Saturn’s rings in the infraredNASA/ESA/CSA/JWST/Tiscareno et al.
The rings are made up of swarms of rocks and chunks of ice, these fragments have very different sizes: from a grain of sand to a terrestrial mountain. One of the most surprising characteristics of the rings is that they are extremely thin: their vertical thickness is barely one kilometer. That is, if we consider the ratio of their thickness to their width, in proportion the rings turn out to be much thinner than a razor blade.
The Cassini divide, which separates the A and B rings, is about 4,800 kilometers wide, while the Encke divide, an annular gap within the A ring, is only 325 kilometers wide.
Remedy
Three of Saturn’s moons – Dione, Enclado and Tethys – are also clearly visible on the left side of the new infrared image. However, these are not the largest moons of the giant planet, the largest – Titan, Rhea and Ipetus – are not observable in this snapshot. Let’s remember that 83 moons are already known in Saturn
The same Webb telescope has recently been used to observe one of the most interesting of these moons: Enclado, from whose south pole immense geysers of water vapor emerge. The results were published in Nature and the article can be consulted in this link . The plumes reach a height of about 10,000 kilometers above the surface of Enclado, that is, about twenty times the diameter of the moon. Some of the material from these plumes feeds into Saturn’s E ring.
Steam plume in EncladoNASA/ESA/CSA/JWST/G. villanueva
NASA announces that Webb has already taken deeper images of the entire Saturn system, including its moons and rings. Details of the fainter rings and minor satellites should appear in such images. So the images that we show here only represent a small appetizer of what is to come.
raphael bachelor is director of National Astronomical Observatory (National Geographic Institute) and academic of the Royal Academy of Doctors of Spain.
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