+- Scivillage.com Casual Discussion Science Forum (https://www.scivillage.com)
+-- Forum: Science (https://www.scivillage.com/forum-61.html)
+--- Forum: Biochemistry, Biology & Virology (https://www.scivillage.com/forum-76.html)
+--- Thread: Life really may be unique to Earth: Radiation makes 'habitable zones' inhospitable (/thread-9571.html)
Life really may be unique to Earth: Radiation makes 'habitable zones' inhospitable - C C - Dec 28, 2020
https://www.studyfinds.org/life-unique-to-earth-planets-inhospitable/
EXCERPTS: . . . Researchers from the University of Sydney say that life really may be unique to Earth, after all. Prior studies in recent years suggest the universe could be teeming with life. But that is unlikely to be the case, explains the Aussie team. They show that the first weather forecasts from our solar system’s next door neighbor are a massive setback for alien hunters.
The discovery has implications for other distant planets, too. It will make it easier to detect their atmospheric conditions. According to their study, an Earth sized waterworld only 4.2 light years away is inhospitable, despite being in the “habitable zone.” The rocky planet, named Proxima b, is being bombarded with radiation, they say. The planet lies too close to Proxima Centauri, a type of star known as a red dwarf, and the most common.
Unfortunately, the reports from Proxima Centauri are not promising for “finding life as we know it.” Habitable zones closer than Earth’s would rule it out. [...] “This is probably bad news on the space weather front ... It seems likely the galaxy’s most common stars, red dwarfs, won’t be great places to find life as we know it.”
Proxima b is about 4.7 million miles from its star, taking about eleven days to complete an orbit. That’s compared to Earth’s 93 million miles and 365 days, respectively. “Our own Sun regularly emits hot clouds of ionized particles during what we call ‘coronal mass ejections. ... But given the Sun is much hotter than Proxima Centauri and other red-dwarf stars, our ‘habitable zone’ is far from the Sun’s surface, meaning the Earth is a relatively long way from these events. Further, the Earth has a very powerful planetary magnetic field that shields us from these intense blasts of solar plasma.”
There are now more than 4,000 known exoplanets, or those revolving around stars beyond the solar system. [...] Recent research suggests half the Sun-like stars in the Milky Way could be home to Earth-like planets. But they make up only seven percent of the galaxy’s stellar objects. By contrast, red dwarfs such as Proxima Centauri account for 70 percent.
The findings published in The Astrophysical Journal were based on observational data from space and land-based telescopes that captured the phenomenon in “amazing detail.” They show planets around these stars are likely to be showered with stellar flares and plasma ejections. It suggests they suffer strong atmospheric erosion, leaving them exposed to very intense X-rays and ultraviolet radiation... (MORE - details)