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 hundreds of different asteroids within the ever-growing catalog of near-Earth objects. But a current information article in The Jerusalem Post described them in a somewhat eye-catching, even startling, means: Each rock, the story mentioned, is “around the size of 22 emperor penguins stacked nose to toes.”
Now, if somebody requested me to explain the scale of an asteroid (or something, for that matter), penguins wouldn’t be the primary unit that involves thoughts. But the penguin asteroid is barely the most recent instance of a typical technique in science communication: evoking pictures of acquainted, earthly objects to convey the scope of mysterious, celestial ones. Usually, small asteroids are mentioned to be the scale of buses, skyscrapers, soccer fields, tennis courts, vehicles—mundane, inanimate issues. Lately, although, the conference appears to be veering towards the bizarre.
Also this month, the identical Jerusalem Post reporter, Aaron Reich, described one other pair of asteroids as “approximately the size of 100 adult pugs.” Last yr, a Daily Mail article wrote that an asteroid that had just lately disintegrated in Earth’s ambiance was “about half the size of a giraffe.” A scientific journal, capitalizing on that article’s recognition, introduced that astronomers would launch a “new asteroid-classification system based on animal sizes”—then revealed that it was solely joking, dismissing the thought as “nonsense.” But perhaps we shouldn’t scoff on the apply of evaluating asteroids to penguins or different delightfully odd issues. Asteroids, like different area objects and phenomena, could be difficult to contextualize. Maybe 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 a real challenge to try and communicate physical properties of something that people aren’t going to actually lay eyes on or have any personal experience with,” Eric Christensen, a University of Arizona astronomer who oversees a program that detects near-Earth objects, informed me. “Nobody’s ever visited an asteroid, so not even astronauts have firsthand experience of what it’s like.” And in the event that they did, they most likely 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 speak about asteroids, they attain for the acquainted. (As for the journalists who write about asteroids, I attempted to contact the authors of the Jerusalem Post and Daily Mail tales, however they haven’t responded). Consider final yr’s marquee space-rock occasion, when NASA crashed a spacecraft into an asteroid as apply for deflecting any future, truly hazardous guests. Some scientists likened the scale of that asteroid, named Dimorphos, to a soccer stadium; others in contrast it to an Egyptian pyramid.
These could be useful pictures, however the strategy has its limitations. “You can be into sports, but if you’re not into U.S. football, these football fields make no sense,” Carrie Nugent, a planetary scientist at Olin College who research asteroids, informed me. And the pyramids of Egypt sound cooler than a stadium, however the analogy is definitely much less efficient in case you’ve by no means been to Cairo. The similar goes for the Eiffel Tower in Paris, the Empire State Building in New York City, and the Burj Khalifa in Dubai—all of which have been used as models of measure in asteroid comparisons.
Penguins, cute as they’re, have the identical shortcoming. (Sorry, penguins!) “I don’t know how many people actually have a good sense of scale for penguins,” Daniella DellaGiustina, a scientist on the University of Arizona who works on a NASA asteroid mission, informed me. “I remember seeing some penguins at the zoo when I was in the Southern Hemisphere, and they were bigger than I thought they would be.” Even if folks can pretty precisely image a penguin, evaluating one thing to 22 of them “requires the reader to imagine 22 (cute!) penguins standing on each other’s shoulders—something no one has ever seen before,” David Polishook, an astronomer on the Weizmann Institute of Science in Israel, informed me in an e-mail. “A comparison with one train car, for example, is much simpler.”
Then there’s the issue of form. A stadium, a pyramid, the Eiffel Tower—these objects all have very completely different outlines. The asteroids that orbit close to Earth are, for essentially the most half, lumps. They are usually not lengthy and slender 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, however it doesn’t actually inform you how large the asteroid is. Using penguins might even be “a bit misleading,” Andy Rivkin, a planetary astronomer on the Johns Hopkins Applied Physics Laboratory who works on NASA’s asteroid-deflection mission, informed me. “If you think about the volume of that body, it’s more like—boy, I don’t know, hundreds of penguins?”
Without a conference to information them, scientists comply with their very own preferences (and so, it appears, do journalists). DellaGiustina likes to invoke landforms, akin to mountains and ridges. “These asteroids are little worlds,” she mentioned. Not solely can we image a mountain, however we are able to additionally most likely think about ourselves mountaineering on a path and feeling the craggy floor beneath us—a thought train that would make a faraway cosmic object much less inscrutable. Nugent likes to deal with as many dimensions as attainable. The asteroid that led to the mass extinction of the dinosaurs is assumed to have been about 10 kilometers (32,000 ft) huge—which, she notes, is near the cruising altitude of an airplane. So “imagine yourself in a plane, and imagine a giant, round rock that goes from your wing tip all the way to the ground, and which takes you over a minute to fly over,” she mentioned. Adding a pile of penguins to this state of affairs would doubtless 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 Daily Mirror in 2019: “Asteroid the Size of BIG BEN Is Hurtling Towards Earth, NASA Warns.” In actuality, no identified asteroid poses a menace to Earth on this century, and we’ll most likely be protected for even longer than that.
When you’re choosing an unconventional unit of measurement, context counts. People generally tend to anthropomorphize absolutely anything space-related, whether or not it’s a robotic or a comet. Some of the general 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. Imagine how way more violent that might 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 fallacious selection within the hypothetical occasion of a giant area rock hurtling straight towards Earth. If a very harmful asteroid have been ever approaching, a very powerful factor for the general public to grasp could be not its dimension, however the extent of the potential destruction it might trigger. Scientists must think about darker metaphors, maybe tallying the vitality of the impression in nuclear detonations.
But for garden-variety asteroids, those that cross proper by us or deplete within the ambiance, animal comparisons may not be so dangerous. Nugent is delighted by the event. Sure, a reader could be dissatisfied to find that the asteroid in query isn’t formed precisely like an alligator, however they could additionally be taught one thing illuminating about asteroids that they wouldn’t have in any other case. Still, let’s take some further care with sure comparisons. After all, describing an asteroid as “half the size of a giraffe” prompts readers to contemplate a somewhat horrifying query: Which half?