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Moon and Saturn

August 21, 2015

Despite years of observations by spacecraft, and centuries by ground-based telescopes, there’s still a lot to learn about the giant planets of the solar system. One of the mysteries is whether Jupiter and Saturn have solid cores. Planetary scientists think they do, but they’re still not certain.

In the case of Saturn, models say it probably has a rocky core that’s about as big as Earth, but perhaps 10 to 20 times heavier. According to a leading idea about how the planets formed, the gravity of that heavy core pulled in vast amounts of hydrogen and helium that was left over from the birth of the Sun. So Saturn grew to giant proportions — it’s the second-largest planet in the solar system.

But there’s a lot of uncertainty about the size of the core, and whether it even exists. In large part that’s because there’s uncertainty about many of the planet’s details — from how fast it spins on its axis to the amount of helium in its outer layers.

And even if Saturn did have a solid core to begin with, a layer of metallic helium around it could have eroded some or all of the core. So it’s going to take a lot more work to fully understand the insides of this giant world.

And giant Saturn is in great view tonight. It stands to the left of the Moon as night falls, and looks like a bright golden star. The true star Antares — the heart of the scorpion — is to Saturn’s lower left. We’ll have more about this lineup tomorrow.


Script by Damond Benningfield, Copyright 2015

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