© NASA, ESA, J.Clark (Boston University) and Z. Levay (STSCI)
FILE PHOTO: Saturn's increasing obliquity means we are sometimes getting a better view of both the rings and the auroras at it's pole than we would if it were more upright.
You know that feeling where your balance isn't quite right and you find yourself falling over very slowly, but with seemingly no power to stop? Saturn knows it too - or would if only it was a sentient being.
Saturn's fall from uprightness is taking hundreds of millions of years, some scientists conclude, laying the blame on its moons.
The gas from which the planets formed swirled in the plane of their orbits. Without anything to change them, each should point straight up at right angles to their path around the Sun. The reality is messier. The angle between a planet's equator and its orbital plane is called its obliquity. Mercury, Venus, and Jupiter behave as expected, with obliquity values of just a few degrees, making their seasons almost undetectable. Mars and Neptune have values a little greater than the Earth's 23.4º, while Uranus has flopped over entirely and is
rotating sideways, and a little backward, its obliquity an improbable
98 degrees.
The reasons for each tilt are as individual as the planets themselves, and sometimes all is not as it seems. Saturn's obliquity of 26.7º - neatly fitting between Mars and Neptune - isn't unusual, but still requires an explanation. Most astronomers believe the cause lies more than four billion years ago when the Solar System was young and resonance with Neptune's orbit tilted Saturn over. Dr Melaine Saillenfest of Sorbonne Université has challenged that, arguing it's actually
happening before our eyes.
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