‘Oumuamua: Our first interstellar visitor

On Oct. 19, 2017, Robert Weryk, an astronomer working at the Haleakala Observatory on Maui, saw something no human had ever seen before: a visitor from another star. The strange object was about a kilometer long, and by the time Weryk spotted it, tumbling wildly into outer space. Over the next two and a half months, scientists around the world scrambled to observe all they could about it before it hurtled out of range of their telescopes forever. That includes its shape, which appears unusually long and thin, and its color, which is possibly a ruddy pink. (There’s a lot of uncertainty in the scientific community.) It has been over a year since we last saw ‘Oumuamua, but its mysteries are only now beginning to unravel. In June, researchers reported that [an unexplained force]( was causing ‘Oumuamua to deviate from its expected trajectory. By November, the head of Harvard’s astronomy department was theorizing that [it could be a piece of alien technology]( setting off a media frenzy. Today, scientists are still poring over the data to answer the many questions ‘Oumuamua left behind—and searching for our next interstellar visitor, which may be waiting right under our noses. Say hello to our solar system’s recent guest. 🐦 [Tweet this!]( 🌐 [View this email on the web]( [Quartz Obsession] 'Oumuamua March 25, 2019 A stranger from a strange star --------------------------------------------------------------- On Oct. 19, 2017, Robert Weryk, an astronomer working at the Haleakala Observatory on Maui, saw something no human had ever seen before: a visitor from another star. The strange object was about a kilometer long, and by the time Weryk spotted it, tumbling wildly into outer space. Over the next two and a half months, scientists around the world scrambled to observe all they could about it before it hurtled out of range of their telescopes forever. That includes its shape, which appears unusually long and thin, and its color, which is possibly a ruddy pink. (There’s a lot of uncertainty in the scientific community.) It has been over a year since we last saw ‘Oumuamua, but its mysteries are only now beginning to unravel. In June, researchers reported that [an unexplained force]( was causing ‘Oumuamua to deviate from its expected trajectory. By November, the head of Harvard’s astronomy department was theorizing that [it could be a piece of alien technology]( setting off a media frenzy. Today, scientists are still poring over the data to answer the many questions ‘Oumuamua left behind—and searching for our next interstellar visitor, which may be waiting right under our noses. Say hello to our solar system’s recent guest. 🐦 [Tweet this!]( 🌐 [View this email on the web]( A new place to talk about the news --------------------------------------------------------------- We’re tired of all the shouting matches and echo chambers on social media. On the new Quartz app, we’ve gathered a community of curious thinkers and doers to have high-quality discussions about the most important stories each day. It’s like an ongoing conversation with CEOs like Richard Branson, Punit Renjen, Arianna Huffington, and many more. [Try the Quartz app]( Giphy By the digits [10,000:]( Estimated number of interstellar objects floating through our solar system at any given moment [1:]( Number of interstellar objects ever observed in our solar system [87.3 km/second:]( Speed at which ‘Oumuamua traveled as it swung past the sun (196,000 miles per hour, or 315,000 kilometers per hour) [1.20:]( ‘Oumuamua’s [orbital eccentricity]( highest ever observed. Anything with an orbital eccentricity greater than 1 has enough speed to escape the solar system. [10:1:]( Ratio of ‘Oumuamua’s length to its width (we don’t know of many objects in our solar system [with a ratio greater than 5:1]( Sponsored by Quartz Community-led Airbnb in rural Japan hopes to save dying town --------------------------------------------------------------- In Nara, Japan, locals take turns running the Yoshino Cedar House Airbnb in hopes of increasing tourism and counterbalancing the shrinking population that has resulted from young peoples’ migration to city centers. Quartz’s 2050 Project pushes the bounds of photojournalism to showcase the ways global cities are reinventing our urban future.[Start exploring on qz.com]( ‘OUMUA-WHO-A? What’s in a name? --------------------------------------------------------------- The space rock currently known as ‘Oumuamua has burned through a lot of names. When it was first discovered, scientists called it C/2017 U1—the “C” at the beginning standing for ‘comet.’ But after a little more observation revealed the object didn’t have a coma (that’s the scientific name for the tail of dust and water vapor that glows behind most comets), researchers re-classified it as an asteroid and gave it the equally charming name A/2017 U1. Eventually, scientists crunched the numbers and definitively proved that they were looking at the first interstellar object they’d ever found in the solar system. To mark this momentous development, they [made up an entirely new classification system]( and honored the visitor with a much more elegant moniker: 1I. But all along, scientists had nicknames for their pet rock. At first, [they briefly toyed with calling it “Rama,”]( after the mysterious, cigar-shaped interstellar object from Arthur C. Clarke’s science fiction novel Rendezvous with Rama. Later, they decided to give it a Hawaiian name, to honor the state where it was discovered. Researchers consulted with two Hawaiian language experts to come up with the name ‘Oumuamua: astronomer Ka’iu Kimura and linguist Larry Kimura. To create it, they combined the Hawaiian word ‘ou, meaning “to reach out for” with mua, which means “first” or “in advance of,” and is reduplicated for emphasis. Taken together, [the name roughly translates]( to “scout” or “a messenger sent from the distant past to reach out to us.” Watch this! ‘Oumuamua’s origin story --------------------------------------------------------------- Karen Meech, one of the scientists who discovered ‘Oumuamua, tells the story of how researchers found the mysterious object, battled for telescope time to observe it, and raced to answer their questions about it as it hurtled out of sight. Brief history [1837:]( ‘Oumuamua enters our solar system (but is still much too far to see from Earth). [1973:]( Arthur C. Clarke publishes Rendezvous with Rama, in which a strange, cylindrical interstellar visitor turns out to be a spacecraft. [Oct. 14, 2017:]( ‘Oumuamua hurtles past Earth at the closest point in its trajectory, about 15 million miles (24 million km) away. [Oct. 19, 2017:]( Scientists at the Haleakala Observatory in Hawaii spot ‘Oumuamua for the first time. [Jan. 2, 2018:]( Earth gets its last glimpse of ‘Oumuamua, captured by the Hubble Space Telescope. [January 2019:]( ‘Oumuamua passes Saturn on its way out of the solar system. [2038:]( ‘Oumuamua will overtake the Voyager probes, the farthest man-made objects from Earth. Have a friend who would enjoy our Obsession with 'Oumuamua? [ [Forward link to a friend](mailto:?subject=Thought you'd enjoy.&body=Read this Quartz Obsession email – to the email – Giphy MILLION-DOLLAR QUESTION Is it an alien spaceship? --------------------------------------------------------------- On Nov. 8, 2018, Abraham Loeb, the chair of the Harvard astronomy department, and his postdoc student Shmuel Bialy [sent the press into a tizzy]( when they [released a paper]( theorizing that ‘Oumuamua could be a piece of debris from an alien spaceship. Their theory addresses a very real mystery. As ‘Oumuamua zips out of the solar system, it isn’t following the trajectory that scientists would expect, given the force of the sun’s gravity. ‘Oumuamua is moving a little faster than it should. In fact, it seems there is some small but significant force accelerating it away from the sun. That would be normal if ‘Oumuamua were a comet. Comets—dirty space snowballs made mostly of ice, dust, and trapped carbon dioxide and methane—often get a little kick from a process called outgassing. As they pass by a star, the ice melts, releasing gasses that propel the comets forward and create their characteristic tails. But ‘Oumuamua doesn’t have a tail, and [there’s no evidence]( that its acceleration comes from outgassing. Instead, Loeb and Bialy propose that ‘Oumuamua is accelerating thanks to solar radiation pressure—that is, the impact of many, many tiny radioactive particles emanating from the sun, whizzing through space, and smacking into it. In order for this theory to work, ‘Oumuamua would have to have a big surface area and be [“less than a millimeter thick.”]( Objects in nature don’t form that way. So Loeb and Bialy floated the idea that an advanced alien civilization built it. The duo’s idea is [based on the concept of a lightsail]( which some scientists ([including Loeb]( have argued we should use to send probes to nearby stars. Lightsails work like the sail on a ship, except instead of catching wind, they catch solar radiation, and use it to push a spacecraft forward. Quotable “I was furious for several reasons…. [Harvard astronomer Avi Loeb] went through all the maths, and went for the most exotic, unreasonable solution with no proof whatsoever.” —[American astrobiologist Karen Meech on her reaction]( to Loeb’s theory that ‘Oumuamua is an alien lightsail “In contemplating the possibility of an artificial origin, we should keep in mind what Sherlock Holmes said: ‘when you have excluded the impossible, whatever remains, however improbable, must be the truth.'” —[Avi Loeb, “6 Strange Facts About the Interstellar Visitor ‘Oumuamua”]( Giphy OKAY, FINE If it’s not aliens, what is ‘Oumuamua “really”? --------------------------------------------------------------- Scientists are still poring over ‘Oumuamua observation data to come up with alternatives to the alien hypothesis. There are a [host of possibilities](. (In November 2018, Loeb laid out [six “strange facts”]( about ‘Oumuamua that led him to his hypothesis.) ‘Oumuamua might be a giant snowflake. There’s another explanation for ‘Oumuamua’s mysterious acceleration that doesn’t require it to have been built by alien shipwrights. In order to be propelled by solar radiation, it needs a large surface area, to catch as much radiation as possible, and a very low volume, so that the tiny push from the impact of photons could have a noticeable impact. It could have both of these traits if it were a [very large, very puffy snowflake](. When a star forms, heaps of dust and water swirl around it. At the edges of the star system, the water freezes and connects with its neighbors in complex, repeating patterns called fractals. ‘Oumuamua could be a fractal that grew large, then spun out of its native solar system—but it’s unclear how such a delicate object would survive the trip around our sun. ‘Oumuamua might be the skeleton of a comet. Zdenek Sekanina of NASA’s Jet Propulsion Lab argues that [our interstellar visitor could be the husk of a comet]( after all its ice and gas has burned off. Comets usually disintegrate at some point, but Sekanina points out that if it didn’t, it would have a light, porous structure similar to a fractal that could be accelerated by solar radiation. ‘Oumuamua might be a pure-water comet. The simplest explanation for ‘Oumuamua’s acceleration away from the sun would be outgassing, but observations from the Spitzer Space Telescope found no evidence of carbon monoxide or carbon dioxide escaping from the object’s surface. If ‘Oumuamua is anything like the comets in our solar system, which are full of water and carbon gases, we’d assume that means ‘Oumuamua has no tail and isn’t a comet. But Yale astronomer Gregory Laughlin muses that ‘Oumuamua might be a weird comet that is full of pure water, or different kinds of non-carbonated gases. (“‘Oumuamua is made of still water, not Perrier,” he [joked to Science News]( That would mean ‘Oumuamua’s acceleration can be explained by outgassing after all—we just didn’t have the right tools to observe it. Fun fact! After discovering ‘Oumuamua, astronomers searched through archived images to find traces of the interstellar object from before we knew it existed in a process called “[precovery]( SPACE ODYSSEY Where did ‘Oumuamua come from? --------------------------------------------------------------- As ‘Oumuamua makes its hasty exit from our solar system, scientists are working to reconstruct the path it took to get here. They hope to eventually [pinpoint ‘Oumuamua’s home star](. To recreate its long journey, scientists combined observations of ‘Oumuamua’s path through our solar system with data from the European Space Agency’s Gaia mission, which released a massive trove of information on the positions and motion of 1.3 billion stars. Researchers rewound ‘Oumuamua’s path using computer models that took into account the gravitational effects of all the stars our interstellar visitor passed on its way to us. In September, they [narrowed their search down to four candidates]( all little-known dwarf stars that would have passed near ‘Oumuamua’s simulated trajectory between 1.1 million and 6.3 million years ago. For now, that’s as precise as the scientists can get. But in 2021, the Gaia mission will release another massive star dataset, 10 times larger than 2018’s data dump, which might narrow the field or identify more potential candidates. Giphy Poll Do you think alien tourists have visited our solar system? [Click here to vote]( Only in science fictionWe’re not aloneWho cares? 💬let's talk! 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