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What the cloud layers above Saturn’s hexagon are made of

Jupiter has its Great Red Spot – Saturn, in contrast, has its enormous hexagon. For a long time, a six-sided structure with a diameter of 29,000 km (18,000 miles) has been rotating around Saturn’s north pole. Thus, the hexagon is considerably larger than Jupiter’s spot, which is only 16,000 km (10,000 miles) across and more than twice as large as the whole Earth. The hexagon was first discovered in 1981 by Voyager 1 (photographed in infrared in the image below).

Starting in 2006, the Cassini probe, operated by NASA and ESA, made it possible to take a detailed look at the structure of the hexagon, which needs about ten hours and 39 minutes for one rotation. It appears to be clear that the hexagon is formed by jet streams moving at speeds greater than 300 km/h (186 mph). But how the unusual shape is created has not yet been completely explained. One cause might be that the wind speeds vary greatly depending on latitude. In laboratory simulations in a round water tank, regular polygons also formed when the liquid in the center rotated faster than at the edge.

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Silent Sun: The phenomenon of our quiet star

The Sun is rather quiet. That’s the premise of my novel “Silent Sun.” But now researchers at the Max Planck Institute for Solar System Research (MPS) in Göttingen, Germany have also proved it with a systematic comparison published in Science. In such analyses, of course, it is important to make sure you are not comparing apples with oranges. Red dwarfs, for example, are considered much more active. But even among the class of yellow dwarfs like the Sun, there can be big differences.

Therefore, the researchers selected candidate stars that were similar to the Sun in terms of important characteristics. In addition to surface temperature, age, and proportion of heavy elements, another characteristic was rotational velocity. “The speed at which a star rotates about its own axis is a crucial variable,” says Sami Solanki, director at MPS and co-author of the study.

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How monster galaxies feed off of their neighbors

In very large, ancient galaxies, usually more than ten billion light-years away from us, many stars behave differently than in the Milky Way, where the large majority of stars obediently follow the motion of arms rotating about the center of the galaxy. Why is that? It seems galaxies have something in common with people: when there’s too much substance around their mid-sections, it’s usually a result of too much eating. Giant galaxies have swallowed up too many of their neighbors, one after the other, as researchers have now shown in the Astrophysical Journal.

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Blown to dust: the first exoplanet visible in a telescope is no more

In 2008, researchers looking at images from the Hubble Space Telescope found a bright spot moving around the star Fomalhaut located 25 light-years from Earth. At 400 million years old, Fomalhaut is still relatively young. The star, twice as heavy as the Sun and 17 times brighter, is also circled by a dust disk that the researchers identified as a remnant from planetary formation.

Fomalhaut b was thus the first exoplanet detected through direct, optical imaging, not just indirectly through star crossings or wobbling patterns of movements by its star. In 2015, the approximately Jupiter-sized planet was even given its own name, Dagon. However, over time, astronomers noticed a few strange things. For one, the planet appeared significantly brighter than it should have been. Its orbit also appeared to be very eccentric, with an orbital period of 2000 years and its distance to its star varying between 49 and 290 astronomical units.

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