Jupiter’s moons can heat each other

Jupiter’s four largest moons in order of distance from Jupiter: Io, Europa, Ganymede and Callisto. Sincerely: NASA

Jupiter’s moons are hot.

Well, in order to be so far away from the sun, they need to be as warm as possible. In a process called tidal heating, gravity tugs from Jupiter’s moons and the planet itself squashes the moon enough to stretch and warm them. As a result, some icy moons warm inward to host oceans of liquid water, and in the case of the rocky moon IO, tidal heating melts the rock in the magma.

Researchers previously believed that the gas giant Jupiter was responsible for most of the tidal ebb associated with the liquid interiors of the moon, but a new study appeared. Geophysical research paper It was found that the Moon – Moon interaction may be more responsible than Jupiter than the Moon alone.

“This is surprising because the moons are much smaller than Jupiter. You wouldn’t expect them to be able to produce such a large tidal response,” said the paper’s lead author Hamish Hay, a postdoctoral fellow at the Jet Propulsion Laboratory in Pasadena Said, California, which he did research when he was a graduate student at the University of Arizona and the Planetary Science Laboratory.

Understanding how moons affect each other is important because it can shed light on the evolution of the lunar system as a whole. Jupiter has about 80 moons, of which the four largest are Ayo, Europa, Ganymede and Callisto.

“To maintain subsurface oceans against freezing over geological time requires a fine balance between internal heating and heat loss, and yet we have many pieces of evidence that Europa, Ganymede, Callisto and other moons Has to be the world of the ocean, ”said co-author Antony Trinh, a postdoctoral research fellow at the Lunar and Planetary Lab. “Ayo, the moon closest to Jupiter, shows another result of widespread volcanic activity, tidal heat, but at a higher intensity experienced by other terrestrial planets like Earth, in its early history. Ultimately, we all want to understand the source of Are. This heat, both across the solar system and beyond it for its impact on the development and habitability of many worlds. ”

Tidal resonance

The speed of tidal heating is a phenomenon known as tidal resonance.

“The resonant load creates more heating,” Hay said. “Basically, if you push an object or system and let go, it will waver at its natural frequency. If you keep pushing the system at the correct frequency, those oscillations become larger and larger, like You are pushing. ” Swing. If you advance the swing at the right time, it becomes longer, but the timing goes wrong and the swing speed decreases. ”

The natural frequency of each moon depends on the depth of its ocean.

“These tidal resonances were known before this work, but are only known for tides caused by Jupiter, which can only create this resonance effect if the ocean is indeed thin (less than 300 meters or less than 1,000 feet). , Which is unlikely, “Hay said. “When tidal forces act on a global ocean, it creates a tidal wave on the surface that ends the propagation around the equator with a fixed frequency or duration.”

According to the researchers’ model, the effect of Jupiter cannot produce tides with the correct frequency to resonate with the Moon alone because the Moon’s oceans are considered too thick. It is only when researchers have added to the gravitational effects of other moons that they started moving tidal forces closer to the natural frequencies of the moon.

When the tides generated by other objects in Jupiter’s lunar system match each moon’s own resonant frequency, the moon begins to experience even more heat due to the tides raised by Jupiter alone, and in the most extreme cases, it Melting of ice can result. Or rock internally.

For moons to experience tidal resonance, their oceans must range from tens to hundreds of kilometers – a maximum of a few hundred miles, which is in the range of current estimates by scientists. However, there are some caveats to the researchers’ findings.

His model assumed that tidal resonance is never overdone, Hay said. He and his team want to return to this variable in the model and see what happens when they lift that constraint.

Haye is also hoping that future studies will be able to estimate the actual depth of the oceans within these moons.

Ocean in Jupiter’s Moon Europa ‘may be habitable’

more information:
Hamish CFC Hay et al, Empowering Gallion Satellites with Moon ides Moon Tides, Geophysical research paper (2020). DOI: 10.1029 / 2020GL088317

Provided by the University of Arizona

Quotes: Jupiter’s moons may heat each other (2020, September 10) Retrieved September 11, 2020, from https://phys.org/news/2020-09-jupiter-moons.html

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