On December 7 we get the year’s earliest sunset, followed by the shortest day on December 21 and the darkest morning in early January. This timing doesn’t match the solstice because Earth’s tilt and elliptical orbit make our solar day slightly longer than 24 hours as we move fastest near early January. That small shift moves sunrise and sunset milestones off the solstice, meaning the darkest-feeling afternoon of winter arrives now.

The universe is shaped by four fundamental forces, including gravity and electromagnetism. The latter’s strength is described by the dimensionless constant alpha (about 0.008), a value long puzzling to scientists such as Wolfgang Pauli. In 2010, astrophysicists analyzing quasar light found that alpha appeared slightly larger in one direction of the sky and smaller in the opposite, suggesting this supposedly unchanging constant might vary across the cosmos. Tune in to hear how such a directional shift would challenge Einstein’s relativity, hint at an even larger — possibly infinite — universe with fundamentally different cosmic “neighborhoods,” and suggest that life exists here partly because our region of the universe is unusually suited to it.

My autograph collection includes a handwritten note from Aldous Huxley saying “Gratitude is heaven itself,” a fitting thought with Thanksgiving approaching. I’m thankful for many things, including resisting the urge to play mood music at my observatories, since tastes differ and silence still best suits the Orion Nebula in Ulster County. The holiday also prompts a modern cosmological question: whether the universe is an interconnected whole with some underlying intelligence rather than a product of randomness. This idea has scientific grounding, since the laws of physics and the four forces are astonishingly fine-tuned for life—small changes to the strong force or gravity would make stars, water, and life impossible. So we’re left to wonder whether such precision needs an explanation, and whether Nature itself might hold some unseen intelligence, as scientists continue trying to make sense of a cosmos that seems improbably well-suited to us.

To understand climate change, we can look to Venus and Mars, both surrounded by carbon dioxide—the main greenhouse gas. On Venus, CO₂ traps enough heat to keep the surface at 850°F, while on Mars, a much thinner layer still warms the planet by about 40 degrees. Greenhouse gases work by trapping infrared energy: when the Sun heats Earth’s surface, most infrared escapes through simple gases like oxygen and nitrogen, but CO₂ and water vapor absorb and re-radiate it, sending some back toward the ground. This process keeps Earth warmer and explains why cloudy nights are warmer than clear ones—the same physics behind climate change.

Stars, planets, and even our bodies come and go, since permanence is the one thing that nature seems unable to create. The only thing that is enduring is: repetition. Tune in to hear what is repetitious in our galaxy.

Everything in nature comes and goes—stars, planets, even our bodies—but what truly endures is repetition. The universe moves to a rhythm: the Sun brings the year’s shortest day on December 21 and its earliest sunset on December 7; the Moon cycles through fullness every 29½ days and repeats its elevation pattern every 18.6 years, reaching an extreme this year. Venus, fading from the morning sky, will return as a brilliant evening star later this winter—part of its elegant 8-year cycle. Saturn’s rings, now edgewise, won’t appear this way again until 2044. Even Earth’s poles follow a 26,000-year rhythm, and we’re now living in the rare moment when Polaris serves as the most perfectly placed North Star in that grand celestial cycle.

While childhood fears like nyctophobia—the fear of the dark—are common, even the Pleiades star cluster, traditionally linked to ominous folklore, adds to the eerie atmosphere as it rises each Halloween. But the real cosmic fright comes from science: in 1998, astronomers discovered that the universe’s expansion is accelerating—driven by a mysterious force called dark energy. With galaxies racing apart in an inexplicable frenzy, the universe may be headed toward a cold, empty end. Fittingly, it’s all part of the mystery in the Halloween night sky.

As autumn colors reach their peak, it's natural to wonder if the sky can show vivid hues too. Stars emit blue, red, and green light, but our eyes usually see them as white due to the mix. Cooler stars appear redder, while hotter ones lean blue, but the difference is subtle. Stars like Antares (red), Arcturus (orange), and Vega (blue-white) show noticeable color shifts. More intense colors appear when the Sun or Moon is low or during meteor showers, with green shooting stars standing out. The solar maximum has also triggered bright auroras, mostly green but occasionally red, with our eyes more sensitive to green in low light.

It can be tricky to pinpoint the spot directly overhead in the sky, but, you can find it by looking for Deneb, a bright star nearly at the zenith. While not as brilliant as nearby Vega, Deneb is one of the most luminous stars in the sky, shining with the power of 58,000 Suns from 1,500 light-years away. If it were as close as Sirius, its light would outshine our streetlights. Deneb is also significant because it lies in the direction Earth is moving as the Sun carries us around the galaxy at 144 miles per second. Though we’ll never catch it—it’s moving too—it’s still a powerful feeling to look up and point toward the future.

Saturn Made Easy: Saturn is a stunning sight through any telescope with more than 30x magnification—something photos can’t quite capture. It’s usually hard to spot, dimmer than Jupiter or Venus and less colorful than Mars, but now is the perfect time to see it. Saturn is closest to Earth and visible just below the Moon. Its famous rings, currently angled edgewise—a rare view that happens only every 15 years—appear as a straight bright line across the planet. Finding Saturn is easy: just look for the Moon.