Calculations indicate that collisions between moons and planets might be a common threat to alien life.
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Home News ‘Unstable’ moons might be wiping out extraterrestrial life throughout the cosmos.
By Briley Lewis, released twenty minutes ago
Calculations indicate that collisions between moons and planets might be a common threat to alien life.
A diagram depicting a moon-like object forcefully colliding with a planet-like Earth in a distant solar system.
The moon falling onto Earth may sound like an implausible end-of-the-world scenario or the stuff of science-fiction catastrophes. For planets in other star systems, however, such catastrophic impacts may be the norm.
New research published in the journal Monthly Notices of the Royal Astronomical Society uses computer simulations to demonstrate that collisions between exoplanets and their moons (called exomoons) may be a common occurrence, which could be catastrophic for any alien life that may be developing on these planets.
Although astronomers have not yet detected an exomoon with certainty, scientists anticipate that they are abundant in the cosmos.
Jonathan Brande, an astronomer at the University of Kansas who was not involved in the new study, told Live Science in an email, “We know of many moons in our own solar system, so it’s only reasonable that we would expect to find moons in exoplanet systems.” Therefore, theorists such as Brad Hansen(opens in new tab), an astronomer at the University of California, Los Angeles, and author of the new study, are interested in examining how alien moons and exoplanets may interact, and how these interactions may impact the likelihood of life in distant star systems.
Runaway moons
Gravity governs the interactions between a planet and its moons, manifesting as tides and other consequences, such as the gradual receding of our moon. Each year, the moon moves a fraction of an inch further away from our planet, causing its orbit to expand. Likewise, the Earth spins a bit more slowly each year. These two phenomena are intimately related: the Earth transfers part of its angular momentum to the orbit of the moon.
If this exchange continues for long enough, the moon might someday become untethered from the Earth. Fortunately, this procedure would take so long that the sun would explode before the moon could completely escape. Hansen’s estimates indicate that planets and their “instable” moons might collide during the first billion years of their creation around some exoplanets, particularly those that are far closer to their stars than the Earth is to the sun. (The Earth and its moon are around 4.5 billion years old in comparison.)
In his simulations, moons that strayed from their home planets frequently returned with a thud, crashing into the planet and generating enormous dust clouds. As they were irradiated and heated by the star’s radiation, these dust clouds shone in the infrared. Yet, they barely lasted roughly 10,000 years before disappearing – a cosmic blink of an eye.
Hansen stated that observations from NASA’s Wide-field Infrared Survey Explorer satellite observatory indicate that every star would experience one of these events at some point during its existence. He said that it is likely that these dust emissions are the result of collisions between planets and their moons.
Due to the limited duration of these dust storms, astronomers have only observed a dozen of them. In addition, some astronomers are still not sure that these dust clouds originate from exomoons, arguing that they may be the consequence of planet impacts. In any case, further observations are required to identify the significance of exomoons in the development of an exoplanet and to discover whether these impacts may impact extraterrestrial life.
“Moons are frequently viewed as beneficial,” Hansen stated. They are believed to help regulate the tilt of a planet’s axis, resulting in milder, more hospitable seasons. Yet, a collision comparable to those in Hansen’s models would likely exceed this advantage by obliterating any chances of survival in a catastrophic explosion.
“Every couple of weeks, it seems, a CGI video(opens in a new tab) goes viral depicting the destruction of Earth by a gigantic cosmic impactor,” Brande said. “If you were unfortunate enough to dwell in primordial slime on a young, rocky exoplanet, you may discover what you would truly do in such a circumstance! Hardly the most promising outcome in the quest for alien life, but nonetheless worth knowing.”