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The Week in Space and Physics: Solar Storms Up Close
On gigantic solar storms, the scent of alien life, OSIRIS-REx and a vast bubble of galaxies
Back in 1859, a solar astronomer named Richard Carrington spotted something strange. Two patches of the Sun, he later wrote, had suddenly flared up in brightness; shining a brilliant white before bursting away from the Sun’s surface at incredible speed. Each was vast, greater in size than Jupiter, and each, it soon turned out, was heading directly for Earth.
When they struck, several hours later, they sparked dramatic events across the planet. People as far south as Mexico and Hawaii saw aurora dancing in the skies. Those further north recorded the sky turning blood red in colour, lighting up with such brightness that some thought dawn was breaking.
It was, we now know, a solar storm, triggered by a massive outburst from the Sun’s surface. Such storms regularly hit the Earth, though none has since matched the power of the 1859 event. If, or rather when, one of such fury does again strike, it threatens to cause chaos. Solar storms bring intense magnetic and electrical fields with them, and so can wreak havoc on our electrical grid. In the worst case entire continents could be left without electricity for weeks on end.
Such massive storms are, however, still somewhat mysterious. Astronomers do not yet know how often they take place, and so whether we should expect another such Carrington storm in a decade or in a century. They do not know, even, if the Sun is capable of even greater storms - though some frightening hints suggest that it is.
Last September, according to a recent paper, NASA’s Parker Solar Probe flew through an outburst close in size to that seen by Carrington. The event, which took place as the probe was soaring a few million miles from the Sun, lasted about two days and was, luckily, facing away from the Earth.
Parker was designed to withstand such outbursts, so it passed through the tempest unscathed. It did, however, send back valuable data from the heart of the storm, giving astronomers an unprecedented view of such a powerful event. That has already allowed them to build a rough timeline of how such storms play out - and revealed an unexpected stage of the outburst never seen before.
The storm, like others, began with a shockwave and a surge of solar plasma. Later came a region more akin to the typical solar wind, before a final stage where the flow of particles slowed and became far less dense than usual. The first two of these stages are well known, having been observed when past storms hit Earth. The last slow stage, though, seems to be something new.
All this data is challenging our existing models of solar storms. In time, and as Parker observes other solar storms, that should help us better understand what is going on when such events form. That should give us more insight into how often big solar storms take place - and, indeed, help us prepare for when a big one does, once again, smash into the Earth.
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The Scent of Alien Life?
Good news everyone! Researchers have sniffed out a chemical on a distant planet that may hint at the presence of alien life. If so it is an extraordinary discovery; the strongest evidence thus far of life beyond Earth. If not, the finding at least shows the potential for our most advanced telescopes to spot traces of life on faraway worlds.
The discovery was made with the James Webb Space Telescope. The planet in question is known as K2-18b, and lies about one hundred and twenty light years away. It is thought to be a “Hycean world”, a previously hypothetical type of planet that hosts vast oceans and a thick hydrogen rich atmosphere. Though these worlds are very different to Earth, astronomers have, in the past, speculated about the possibility of life arising on them.
K2-18b, data from the James Webb shows, has an atmosphere rich in both carbon dioxide and methane. That, together with a lack of ammonia, suggests the planet has a deep ocean under a thick atmosphere - matching, in other words, what we think a Hycean world would look like. The planet also lies in the habitable zone around its star - putting it at the right temperature for life, if any exists, to thrive.
That is as far as many studies go. Yet in this case, astronomers also spotted signs suggesting the presence of dimethyl sulfide, a gas, in the planet’s atmosphere. On Earth this chemical is only made by living creatures - though, scientists caution, this may not be the case on a planet as alien as K2-18b.
For now, at least, the evidence for its presence is still rather weak. More observations are needed to prove it is actually there, and then, if it is, to confirm that life is the only explanation for its formation. Not would that life need to be very complex - on Earth most dimethyl sulfide is created by oceanic plankton.
Still, the discovery shows how the James Webb is beginning to probe distant planets for the chemical signatures of life. Other discoveries like this are sure to come in the years ahead. Some planets - those in the Trappist solar system, for example - are already under intense study. The possibility of alien life, however simple that life is, may soon look a lot more real.
The Return of OSIRIS-REx
Early on Sunday morning, at a distance of some sixty thousand miles, the OSIRIS-REx probe fired a small capsule towards Earth. Four hours later, after making a fiery reentry over Utah, the capsule successfully touched down. With it came NASA's first sample of rocks collected directly from an asteroid.
That sample was collected in 2020, when OSIRIS-REx landed on Bennu and picked up a few hundred grams of rock. After departing the asteroid in April 2021, OSIRIS-REx spent two years flying back to Earth, carrying its precious cargo with it.
This is not, though, the first time that samples of comets or asteroids have been brought back to Earth. Japan’s space agency, JAXA, has successfully returned material from two asteroids, most recently in 2020. NASA’s Stardust mission also captured samples from the tail of a comet, landing in 2006.
Osiris’ sample should include pristine rocks from the early solar system. Within them could be chemicals based on carbon and hydrogen - which researchers believe were crucial to the formation of life. On Earth traces of these molecules have long since been lost, making it hard for us to understand the chemistry from which biology first emerged. Evidence from Osiris, presumably uncontaminated by living beings, should help answer that question.
The probe itself, meanwhile, has set off on a new mission. Over the next six years it will fly towards the asteroid Apophis, reaching it in 2029, just after the asteroid makes a close approach to Earth. Apophis, scientists reckon, is a high-risk asteroid, with some projections showing it could one day collide with Earth.
Bubbles in Space
Astronomers have long known that galaxies cluster in groups, and those groups in turn form structures known as superclusters. Our own galaxy is part of a group of several dozen others; and is probably part of the Virgo Supercluster, which may hold thousands of galaxies.
Now astronomers have spotted a cluster of galaxies that seems to form the surface of a gigantic bubble. In size this bubble is extraordinary, measuring a billion light years across. Perhaps fifty thousand galaxies lie on its surface, making it one of the largest structures ever discovered.
How such a structure could have formed is unknown. Perhaps, its discoverers speculate, it is a kind of echo of the Big Bang; a remnant of long ago ripples that spread across the early cosmos. Others think it may have formed through gravitational interactions, which could have slowly sculpted the bubble over billions of years.
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