Did Titan Give Saturn its Tilt?

Giant planets like Saturn don’t just tilt over all by themselves: something has to knock them over, or tug on them gravitationally, to push them off axis. Scientists expect that when new planets are born, they form with almost no tilt at all, lining up like spinning tops, with their equators level to the orbital plane in which they circle around their sun.

But no planet in our solar system is perfectly level. Jupiter is the closest, boasting an obliquity (tilt) of just 3.12 degrees. Earth’s obliquity is much more substantive at 23.45 degrees, causing us to experience an annual cycle of seasons as our homeworld wobbles on its axis. Saturn’s tilt is more extreme yet, with an obliquity of 26.73 degrees (though it’s nowhere near as extreme as Uranus, which is practically sideways, spinning at a 97.86-degree angle to its orbital plane).

We can learn a lot from these obliquities.

Continue reading “Did Titan Give Saturn its Tilt?”

Astronomy Cast Ep. 353: Seasons on Saturn

You think we’re the only place that experiences seasons? Well, think again. Anything with a tilt enjoys the changing seasons, and that includes one of the most dramatic places in the Solar System: Saturn, with its rings and collection of moons.

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Tilt-A-Whirl! A Tale Of Strange Planetary Orbits In Kepler-56

A faraway group of planets is puzzling scientists. Newly reported Kepler-56’s system has three planets — two smaller ones close by, and a much larger one further out. The inner planets are orbiting at a tilt to the equator of the host star.

Scientists have seen that tilt before in other systems, but they thought you would need a “hot Jupiter” — a huge gas giant planet close to the star — to make that happen. Here, that’s not the case. The outer planet’s gravity, distant as it is, is pulling the two planets into their tilted orbits.

“This is a very puzzling result that is sure to challenge our understanding of how solar systems form,” stated co-author Tim Bedding, a physics researcher at the University of Sydney.

Kepler-56 is 3,000 light-years away from Earth and has a mass about 30% greater than that of our Sun. As the name implies, astronomers used the Kepler space telescope to make the discovery.

You can read more details in the Oct. 18 edition of Science.

Sources: Iowa State and University of Sydney