A New Model Explains How Gas and Ice Giant Planets Can Form Rapidly

Artist's impression of a young star surrounded by a protoplanetary disc made of gas and dust. According to new research, ring-shaped, turbulent disturbances (substructures) in the disk lead to the rapid formation of several gas and ice giants. Credit: LMU / Thomas Zankl, crushed eyes media

The most widely recognized explanation for planet formation is the accretion theory. It states that small particles in a protoplanetary disk accumulate gravitationally and, over time, form larger and larger bodies called planetesimals. Eventually, many planetesimals collide and combine to form even larger bodies. For gas giants, these become the cores that then attract massive amounts of gas over millions of years.

But the accretion theory struggles to explain gas giants that form far from their stars, or the existence of ice giants like Uranus and Neptune.

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If We Want To Find Life-Supporting Worlds, We Should Focus on Small Planets With Large Moons

A rocky planet with a large moon may have good potential to host life, given that the Moon controls essential aspects for life on Earth, including the length of the day, ocean tides, and stable climate. Image Credit: University of Rochester photo illustration by Michael Osadciw featuring Unsplash photography from Brad Fickeisen, Jaanus Jagomagi, and Engin Akyurt

There’s no perfect way of doing anything, including searching for exoplanets. Every planet-hunting method has some type of bias. We’ve found most exoplanets using the transit method, which is biased toward larger planets. Larger planets closer to their stars block more light, meaning we detect large planets transiting in front of their stars more readily than we detect small ones.

That’s a problem because some research says that life-supporting planets are more likely to be small, like Earth. It’s all because of moons and streaming instability.

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How We Get Planets from Clumping Dust

This artist’s impression shows a young star surrounded by a protoplanetary disk, where dust grains gather together to form planetesimals—the building blocks of new planets. © ESO/L. Calçada

Our gleaming Earth, brimming with liquid water and swarming with life, began as all rocky planets do: dust. Somehow, mere dust can become a life-bearing planet given enough time and the right circumstances. But there are unanswered questions about how dust forms any rocky planet, let alone one that supports life.

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