Earth isn’t the only planet in the solar system with spectacular light shows. Both Jupiter and Saturn have magnetic fields much stronger than Earth’s. Auroras also have been observed on the surfaces of Venus, Mars and even on moons (e.g. Io, Europa, and Ganymede). The auroras on Saturn are created when solar wind particles are channeled into the planet’s magnetic field toward its poles, where they interact with electrically charged gas (plasma) in the upper atmosphere and emit light. Aurora features on Saturn can also be caused by electromagnetic waves generated when its moons move through the plasma that fills the planet’s magnetosphere. The main source is the small moon Enceladus, which ejects water vapor from the geysers on its south pole, a portion of which is ionized. The interaction between Saturn’s magnetosphere and the solar wind generates bright oval aurorae around the planet’s poles observed in visible, infrared and ultraviolet light. The aurorae of Saturn are highly variable. Their location and brightness strongly depends on the Solar wind pressure: the aurorae become brighter and move closer to the poles when the Solar wind pressure increases.
Credit: ESA/Hubble (M. Kornmesser & L. Calçada)
The history of the Milky Way has a new wrinkle.
Scientists used radio telescopes like the Atacama Large Millimeter/submillimeter Array — a vast array of receivers in Chile — used to probe galaxies within 40 million to 600 million light-years from Earth. After observing dozens of merging galaxies, astrophysics found that many galactic collisions will create disc galaxies similar to the Milky Way, a surprising finding.
Their observations of carbon monoxide in 37 colliding galaxies showed pancake-shaped zones of molecular gas, similar to the shape that disc galaxies — which include spiral galaxies and lenticular galaxies — would assume.
"This is a large and unexpected step towards understanding the mystery of the birth of disc galaxies," lead researcher on the study Junko Ueda, a postdoctoral fellow at the Japan Society for the Promotion of Science, said in a European Southern Observatory statement.
Before, astronomers thought that only elliptical galaxies could arise from mergers. Simulations from the 1970s, however, concluded that elliptical galaxies should be the most popular type of galaxy in the universe. Yet these odd-shaped entities comprise less than 30 percent of galaxies. The new study could help explain why scientists see so many spiral galaxies like the Milky Way in the universe, according to ESO.
The astronomers’ work is the biggest molecular gas study so far, but they said they plan more work to follow up on their research. Astronomers emphasized more observations of older galaxies are required to see if mergers behaved similarly in the young universe.
"We have to start focusing on the formation of stars in these gas discs. Furthermore, we need to look farther out in the more distant universe," Ueda said. "We know that the majority of galaxies in the more distant universe also have discs. We, however do not yet know whether galaxy mergers are also responsible for these, or whether they are formed by cold gas gradually falling into the galaxy. Maybe we have found a general mechanism that applies throughout the history of the universe."
The research was published in the Astrophysical Journal Supplement.
How Mandelbrot’s Fractals Changed The World
by Jack Challoner/BBC News
During the 1980s, people became familiar with fractals through those weird, colorful patterns made by computers. But few realize how the idea of fractals has revolutionized our understanding of the world, and how many fractal-based systems we depend upon.
Unfortunately, there is no definition of fractals that is both simple and accurate. Like so many things in modern science and mathematics, discussions of “fractal geometry” can quickly go over the heads of the non-mathematically-minded. This is a real shame, because there is profound beauty and power in the idea of fractals.
The best way to get a feeling for what fractals are is to consider some examples. Clouds, mountains, coastlines, cauliflowers and ferns are all natural fractals. These shapes have something in common - something intuitive, accessible and aesthetic.
They are all complicated and irregular: the sort of shape that mathematicians used to shy away from in favor of regular ones, like spheres, which they could tame with equations.
Mandelbrot famously wrote: “Clouds are not spheres, mountains are not cones, coastlines are not circles, and bark is not smooth, nor does lightning travel in a straight line.”
The chaos and irregularity of the world - Mandelbrot referred to it as “roughness” - is something to be celebrated. It would be a shame if clouds really were spheres, and mountains cones.
Look closely at a fractal, and you will find that the complexity is still present at a smaller scale. A small cloud is strikingly similar to the whole thing. A pine tree is composed of branches that are composed of branches - which in turn are composed of branches.
Fractal images © Laguna Design / Science Source
Mandelbrodt photo © Emilio Segrè / Science Source
alanis: Clouds and shadows on Mars, photographed by Mars Express, 24th May 2012.
Between 28 and 36°S, 284°E, on the arc of highlands that surround the southeast Solis Planum. The crater split between the 2nd and 3rd images is Voeykov, about 75 km across, named for climatologist and geographer Alexander Ivanovich Voeykov (1842-1916). The small, deep crater toward bottom left of the 4th image is Los, named for a village of about 400 people in Gävleborg County, Sweden.
Composite of 3 visible light images for colour, and 5 monochrome images for animation. Colour is not balanced naturalistically, and the slightly psychedelic colours of the clouds are a result of mismatches between the images where the clouds have moved between exposures.
Image credit: ESA. Composite: AgeOfDestruction.
You’re looking at another world. Let that sink in. We will be livestreaming in real time soon…
Ha-Ha-Haikus #25, June 1969