A few newly found asteroids whizzed previous our planet earlier this month, tracing their very own loop across the solar. These two aren’t any extra particular than the 1000’s of different asteroids within the ever-growing catalog of near-Earth objects. However a latest information article in The Jerusalem Submit described them in a somewhat eye-catching, even startling, manner: Every rock, the story mentioned, is “across the measurement of twenty-two emperor penguins stacked nostril to toes.”
Now, if somebody requested me to explain the dimensions of an asteroid (or something, for that matter), penguins wouldn’t be the primary unit that involves thoughts. However the penguin asteroid is barely the newest instance of a typical technique in science communication: evoking photos of acquainted, earthly objects to convey the scope of mysterious, celestial ones. Normally, small asteroids are mentioned to be the dimensions of buses, skyscrapers, soccer fields, tennis courts, vehicles—mundane, inanimate issues. Currently, although, the conference appears to be veering towards the bizarre.
Additionally this month, the identical Jerusalem Submit reporter, Aaron Reich, described one other pair of asteroids as “roughly the dimensions of 100 grownup pugs.” Final yr, a Every day Mail article wrote that an asteroid that had lately disintegrated in Earth’s ambiance was “about half the dimensions of a giraffe.” A scientific journal, capitalizing on that article’s recognition, introduced that astronomers would launch a “new asteroid-classification system primarily based on animal sizes”—then revealed that it was solely joking, dismissing the concept as “nonsense.” However possibly we shouldn’t scoff on the observe of evaluating asteroids to penguins or different delightfully odd issues. Asteroids, like different area objects and phenomena, may be difficult to contextualize. Possibly there’s room for whimsy. A brand new period of asteroid communication could also be upon us.
Scientists don’t have formal tips for describing the character of asteroids on a human scale. “It’s an actual problem to attempt to talk bodily properties of one thing that individuals aren’t going to truly lay eyes on or have any private expertise with,” Eric Christensen, a College of Arizona astronomer who oversees a program that detects near-Earth objects, advised me. “No person’s ever visited an asteroid, so not even astronauts have firsthand expertise of what it’s like.” And in the event that they did, they in all probability wouldn’t assume, Ah, sure, simply as I anticipated—it’s as tall as 40 sea turtles stacked like a sleeve of crackers.
So when astronomers discuss asteroids, they attain for the acquainted. (As for the journalists who write about asteroids, I attempted to contact the authors of the Jerusalem Submit and Every day Mail tales, however they haven’t responded). Think about final yr’s marquee space-rock occasion, when NASA crashed a spacecraft into an asteroid as observe for deflecting any future, truly hazardous guests. Some scientists likened the dimensions of that asteroid, named Dimorphos, to a soccer stadium; others in contrast it to an Egyptian pyramid.
These may be useful photos, however the strategy has its limitations. “You may be into sports activities, however for those who’re not into U.S. soccer, these soccer fields make no sense,” Carrie Nugent, a planetary scientist at Olin Faculty who research asteroids, advised me. And the pyramids of Egypt sound cooler than a stadium, however the analogy is definitely much less efficient for those who’ve by no means been to Cairo. The identical goes for the Eiffel Tower in Paris, the Empire State Constructing in New York Metropolis, and the Burj Khalifa in Dubai—all of which have been used as items of measure in asteroid comparisons.
Penguins, cute as they’re, have the identical shortcoming. (Sorry, penguins!) “I don’t know the way many individuals even have a very good sense of scale for penguins,” Daniella DellaGiustina, a scientist on the College of Arizona who works on a NASA asteroid mission, advised me. “I bear in mind seeing some penguins on the zoo once I was within the Southern Hemisphere, and so they had been larger than I assumed they might be.” Even when folks can pretty precisely image a penguin, evaluating one thing to 22 of them “requires the reader to think about 22 (cute!) penguins standing on one another’s shoulders—one thing nobody has ever seen earlier than,” David Polishook, an astronomer on the Weizmann Institute of Science in Israel, advised me in an e-mail. “A comparability with one prepare automotive, for instance, is far easier.”
Then there’s the issue of form. A stadium, a pyramid, the Eiffel Tower—these objects all have very totally different outlines. The asteroids that orbit close to Earth are, for probably the most half, lumps. They aren’t lengthy and slim like skyscrapers or cruise ships, one other frequent unit of comparability. A stack of emperor penguins would possibly convey the size of an asteroid from one finish to the opposite, nevertheless it doesn’t actually inform you how massive the asteroid is. Utilizing penguins might even be “a bit deceptive,” Andy Rivkin, a planetary astronomer on the Johns Hopkins Utilized Physics Laboratory who works on NASA’s asteroid-deflection mission, advised me. “If you consider the quantity of that physique, it’s extra like—boy, I don’t know, lots of of penguins?”
With out a conference to information them, scientists comply with their very own preferences (and so, it appears, do journalists). DellaGiustina likes to invoke landforms, equivalent to mountains and ridges. “These asteroids are little worlds,” she mentioned. Not solely can we image a mountain, however we are able to additionally in all probability think about ourselves mountain climbing on a path and feeling the craggy floor beneath us—a thought train that might make a faraway cosmic object much less inscrutable. Nugent likes to sort out as many dimensions as potential. The asteroid that led to the mass extinction of the dinosaurs is assumed to have been about 10 kilometers (32,000 toes) extensive—which, she notes, is near the cruising altitude of an airplane. So “think about your self in a aircraft, and picture a large, spherical rock that goes out of your wing tip all the way in which to the bottom, and which takes you over a minute to fly over,” she mentioned. Including a pile of penguins to this state of affairs would seemingly make it extra complicated.
Animal parallels have one clear benefit over buses and the like: They’re assured to attract extra consideration. Christensen mentioned he isn’t very amused by the development, calling it clickbait. Asteroids are already straightforward targets for sensationalist protection; some publications deal with shut approaches to Earth as panic-worthy close to misses. Exhibit A, from The Every day Mirror in 2019: “Asteroid the Dimension of BIG BEN Is Hurtling In direction of Earth, NASA Warns.” In actuality, no recognized asteroid poses a risk to Earth on this century, and we’ll in all probability be secure for even longer than that.
Once you’re choosing an unconventional unit of measurement, context counts. Individuals tend to anthropomorphize absolutely anything space-related, whether or not it’s a robotic or a comet. Among the public response to NASA’s asteroid “redirection” final yr carried a tone of “Oh no, poor asteroid”; certainly, Dimorphos was simply minding its personal enterprise when NASA got here alongside and smashed into it. Think about how far more violent that may have felt if scientists and journalists had in contrast the asteroid to one thing squishier than a stadium. Rivkin suspects that if astronomers had in contrast it to, say, a blue whale, “you’d have these cartoons about us beating up a blue whale.”
Lighthearted comparisons would even be the unsuitable selection within the hypothetical occasion of a big area rock hurtling straight towards Earth. If a very harmful asteroid had been ever approaching, an important factor for the general public to know can be not its measurement, however the extent of the potential destruction it may trigger. Scientists must contemplate darker metaphors, maybe tallying the power of the influence in nuclear detonations.
However for garden-variety asteroids, those that move proper by us or fritter away within the ambiance, animal comparisons may not be so unhealthy. Nugent is delighted by the event. Certain, a reader is likely to be upset to find that the asteroid in query isn’t formed precisely like an alligator, however they may additionally be taught one thing illuminating about asteroids that they wouldn’t have in any other case. Nonetheless, let’s take some additional care with sure comparisons. In spite of everything, describing an asteroid as “half the dimensions of a giraffe” prompts readers to think about a somewhat horrifying query: Which half?
