August 25, 2023: A color wheel of stars, AI can code hidden messages in memes and catch up on our most-read stories of the week. —Andrea Gawrylewski, Chief Newsletter Editor | | | Most stars glow white. But some have a distinct blue, red or yellow hue. A star's color is determined by the temperature of the thermonuclear fusion in its core. The coolest stars burn at around 2,100 to 3,400 degrees Celsius and are tinged red (what's cool is all relative in the sky), whereas the hottest stars (called O stars) can measure 100,000 degrees C and appear blue.
Why this is cool (hot?): There are 10 classifications of star temperature, with a few newer categories added for stars so cool and faint that we have only very recently gained the ability to spot them. Using your naked eye, only the brightest stars are able to activate the color-sensitive cone cells in your eyes, so the fainter ones appear white—that is, colorless. Binoculars or a telescope collect more light than your eyes so they reveal the true colors of stars.
Have a look: This weekend if the skies are clear, look out for Vega, which is almost directly overhead for most Northern Hemisphere observers after sunset in August. It looks washed out by eye, writes astronomer Phil Plait, but "try taking a peek through binoculars. It may sparkle a lovely sky blue when you do.". | | | Whether red, orange, yellow, blue or white, the stars of the globular cluster NGC 6355 all shine like colorful jewels in this image from the Hubble Space Telescope. Credit: ESA/Hubble & NASA, H. Ebeling | | |
How it works: An algorithm chooses an ideal "coupling distribution"—a method that matches secret bits with innocuous content (for example, cat memes) in a way that preserves the right distributions of both while making them as interdependent as possible. A receiver on the lookout for the message can invert the same operation to uncover the secret text.
What the experts say: The technique could be very useful to transmit information such as the "documentation of abuses of human rights under authoritarian regimes and where the information environment is highly restricted, secretive and oppressive," says Joanna van der Merwe, privacy and protection lead at Leiden University's Learning and Innovation Center. | | | • By treating Earth as a topological insulator—a state of quantum matter—physicists found a powerful explanation for the twisting movements of the planet's air and seas, which causes the weather. | 12 min read | | | Colored according to temperature, Earth's ocean currents twist and swirl. Some of these currents appear to be roiling and chaotic, but others are orderly and stable, and they fuel large-scale periodic weather patterns. Credit: NASA/Goddard Space Flight Center Scientific Visualization Studio | | | • "Climate havens" are areas touted by researchers, public officials and city planners as natural refuges from extreme climate conditions, and include the Great Lakes region, upper Midwest and upper Northeast. But these regions will not be immune to the severe impacts of climate change, write Julie Arbit, Brad Bottoms and Earl Lewis, all researchers at the Center for Social Solutions at the University of Michigan. On the contrary, cities in these locations will have to contend with some of the most extreme temperature and rainfall events to come, they say. | 5 min read | | | ICYMI (Our most-read stories of the week) | | | • Fountains of Diamonds Erupt as Supercontinents Break Up | 3 min read | | | • Chandrayaan-3 Makes Historic Touchdown on the Moon | 9 min read | | | • Worm Brains, Decoded like Never Before, Could Shed Light on Our Own Mind | 6 min read | | | It can be upsetting to read about the ways that a warming world is devastating nonhuman animals on this planet. I'm sure our climate editor, Andrea Thompson, would agree that finding that balance point of reporting the news without depressing the hell out of our readers can be a challenge. Let me know how well you think this newsletter is accomplishing that feat. We are still evolving and value your feedback. Email me directly at: newsletters@sciam.com. | Enjoy your weekend and see you back here Monday! | —Andrea Gawrylewski, Chief Newsletter Editor | | Subscribe to this and all of our newsletters . | | | | Scientific American
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