Saturn’s rings are ‘very young’; astronomers explain

When we learn about the planets in the Milky Way, one that stands out for being “different” is Saturn, because of its rings. And for most of the 20th century, astronomers believed that Saturn’s rings had formed along with the planet, 4.6 billion years ago.

However, considering recent information, this idea has been questioned. Because now there is confirmation that the immense rings that adorn the planet are formed mainly by pieces of ice, with only 2% of pollution by rocky material.

So it would be virtually impossible for such a pure composition to emerge amidst the chaos of planet formation, when there was a bunch of rock floating around the Sun. So it was time to redo the calculations.

Studying Saturn’s rings

Between 2004 and 2017, the multisensor Cosmic Dust Analyzer (CDA) was installed on the Cassini mission to study Saturn. Over the course of its thirteen years of analysis, the multisensor generated a wealth of data about the planet.

Using this data, a group of astronomers led by Sascha Kempf of the University of Colorado, Boulder, was able to recalculate the age of Saturn’s rings. To do this, the group investigated 163 dust particles found around the planet.

To make the calculation, the group analyzed the amount of dust accumulated in the rings. These particles of “space dirt” that travel through the Solar System accumulate on celestial bodies.

In practice, just as we can tell how long it has been since we cleaned our house by the thickness of the layer of dust on the furniture, it is possible to tell how old Saturn’s ornament is by the amount of “dirt” it has accumulated. Sascha Kempf explains:

“We call dust everything that is larger than a few atoms and smaller than bodies that are affected by gravity, such as larger rocks. (…) In the Saturn system, the dust is mainly frozen water.”

The analysis then considered the trajectory of the particles at the time of impact with the CDA. Based on this, the group was able to calculate the mass of the particles. Using other data, such as the frequency of impacts, they were able to infer that the rings have probably been accumulating dust (pollution) for “only” a few hundred million years.

The calculations revealed that Saturn’s rings are actually quite young – by astronomical standards, of course –: they are only 400 million years old. To give you an idea, considering this in human years, this would mean getting an engagement ring at the age of 27, a baby.