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April 21, 2025—Meet the wanderers of our solar system. Plus, a new color that exists beyond the range of human vision; and the Pope's influence on climate action. —Andrea Gawrylewski, Chief Newsletter Editor | | Teal is as close as you can get to seeing the new color without having your eyes lasered. Getty Images | | The Japanese Hayabusa2 probe visited the asteroid Ryugu in 2018. It's now on an extended mission to survey more asteroids, including a dark comet. JAXA | | A group of strange space rocks move like comets but resemble asteroids, without the tails of gas and dust that usually propel comets. Their strange movements are a puzzle to astronomers, who have now catalogued 14 of these "dark comets." What's the source of their motion? Why they've found: In an effort to understand them, astronomers have grouped dark comets into two types: "innies" are all 50 meters or less wide and maintain circular orbits in the inner solar system; and "outies," which are larger and follow elliptical orbits into the outer regions of the solar system. What the experts say: "It's hard to explain how they exist in the first place," Alan Fitzsimmons, an astrophysicist at Queen's University Belfast, says of dark comets. "That's just Mother Nature being cleverer than we are. That's what astronomy's all about, figuring out how Mother Nature does stuff. How did that get there?"
Why this is interesting: Scientists don't know where Earth got its water. Some scientists think it was delivered by comets, but most comets live far out in the solar system and don't seem to come close enough to the inner solar system to have done the job. The newfound dark comets, which circle much closer, might help explain this quandary. —Clara Moskowitz, senior space and physics editor | | Jen Christiansen, Source: "Two Distinct Populations of Dark Comets Delineated by Orbits and Sizes," by Darryl Z. Seligman et al., in PNAS, Vol. 121; December 9, 2024 (orbital reference) | | - Experiencing failure can help kids succeed, writes Amy Edmondson, a professor at Harvard Business School. It's up to parents to steer kids toward the right types of failures and mistakes, she says. "To do this, we need to encourage them to take thoughtful risks—to keep stretching outside their comfort zone." | 6 min read
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Marijuana contains more than 500 active compounds. Two of the most crucial ingredients: cannabidiol, or CBD, and THC, which stands for tetrahydrocannabinol, which is the main psychoactive component. Check out the full video for the science of pot and how these chemicals interact.
| | The colors we humans can see represent a small portion of the total electromagnetic spectrum (only 0.0035 percent!). Some animals like birds, honeybees, and select fish can see light at higher frequencies—in the ultraviolet range. Research even suggests that birds's eyes can "see" Earth's magnetic fields, which helps them navigate during long migrations. At any moment, invisible (to us) light and other particles and forces are constantly moving around and through the planet. If we could see beyond the visible spectrum, we'd likely have totally different brains with which to sort through all that input. | | Thanks for exploring this scientific world with me. You can always send your thoughts and feedback to: newsletters@sciam.com. Until tomorrow. —Andrea Gawrylewski, Chief Newsletter Editor | | | | |
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