Tabla de contenidos para October 2025 en Astronomy

A century ago, the fundamental nature of what we know about the universe suddenly turned on its head. In 1920, the so-called Great Debate occurred between Harlow Shapley and Heber Curtis, pitting two opposing ideas about the nature of the cosmos against each other. Shapley believed that spiral nebulae, as they were then known, were relatively close by, lying on the outskirts of the Milky Way Galaxy. Curtis believed they were independent star systems much farther away. Three years later, the young astronomer Edwin Hubble made his way up Mount Wilson, near Los Angeles, and solved the problem. On Oct. 4, 1923, Hubble exposed a plate showing one of his favorite objects, the spiral nebula in Andromeda known as M31. He noted a star that had not been seen before…

SURPRISE SPIRAL While developing an educational show for Hayden Planetarium, scientists noticed a never-before-seen spiral structure in 3D simulations of the inner Oort Cloud, highlighting the value of visualizing data in new ways. HIDDEN WORLD The James Webb Space Telescope has made its first direct imaging discovery of an exoplanet, using a technique that blocks the host star’s light to look for dimmer planets nearby. The Saturn-mass world is called TWA 7 b. ARTIFICIAL ECLIPSE This spring, the two satellites of ESA’s Proba-3 mission lined up to create their first of many artificial total solar eclipses, allowing scientists to study the Sun’s corona without waiting for the Sun, Moon, and Earth to line up.…

MISSING MATTER FOUND? On June 19, astronomers reported a 23-million-light-year-long gas filament glowing in X-rays and connecting four galaxy clusters. If such filaments are common, they could solve the missing baryon problem — the deficit between observed ordinary matter and cosmological predictions. SPACEX SETBACK A Starship upper stage exploded June 18 on a test stand at SpaceX’s site in Massey, Texas, during a static fire test just days before a planned tenth test flight. Starship reached orbit on Flight 9 on May 27, but the vehicle broke apart on reentry. BIGGEST BOOMS Astronomers have identified “extreme nuclear transients” — the most energetic explosions known — as massive stars are shredded by supermassive black holes. These rare events can be 10 times brighter than tidal disruption events, when black holes tear…

IN 1848, JAMES MARSHALL was building a lumber mill in northern California for his employer, John Sutter. One January morning, Marshall spotted sparkling pebbles within the mill’s outflow; Sutter and Marshall soon realized they had found gold in “them thar hills.” The chance discovery sparked the California Gold Rush, with treasure-seeking scouts streaming to the area from as far away as Hawaii, South America, and even Europe. The Gold Rush epitomized abundance of a valued resource in a confined area. In this sense, a new gold rush is now in the making at the south pole of the Moon. The spacefaring nations of the world plan to congregate there, digging for not gold but for water and even answers about our satellite’s history. Entrepreneurs may still come to make a…

THERE IS SOME LUNAR EYE CANDY on the evening of the 2nd. In the south lie the elongated Schiller and the detail-packed Gassendi; the equator sports the small and sharp Kepler, leading north to the outstanding half-ring of the Jura Mountains. Keep going north for some lunar history. The large crater J. Herschel spans 96 miles and betrays its age in two ways. First, the poor rim has been long battered down by smaller impacts and has so many dents that the low-angle sunlight easily streams into the middle. And second, what would have been a complex jumble of central peaks lies buried under the immense amount of rubble thrown out by the giant impact that carved out the Imbrium basin. It looks like someone has kicked dirt on a…

THE SUN GENERATES ENERGY through nuclear fusion, converting some 600 million tons of hydrogen into helium every second. This process began nearly 5 billion years ago, and it will continue for at least another 5 billion years. But the Sun did not pop into existence fully formed. It started its long journey to stardom in a cold molecular cloud. Instabilities within this dusty gas cloud triggered small pockets to contract. Gravity worked its magic, compressing each clump into a smaller and denser sphere while simultaneously drawing in more material from its surroundings. The object’s core heated up, and it radiated energy that eventually escaped as light and heat. Astronomers call such a developing star a protostar; it won’t become a full-fledged star until fusion ignites. Protostars are notoriously difficult to observe…

From Galileo’s meticulous sketches of Jupiter’s moons in 1610 to Caroline Herschel’s handwritten notes of comet discoveries, the history of astronomy is built on careful note-taking. Logbooks with descriptions of as-yet-unknown objects, sketches of Saturn’s rings, and hand-drawn plots of the stars led to numerous discoveries. Today, whether you’re a newcomer scanning the sky with binoculars or a seasoned observer with a telescope, keeping a logbook continues this long tradition, transforming casual stargazing into a personal journey through the universe. Keeping a logbook also allows you to reflect on your journey as an astronomer. Why to log Keeping a nightly observation log has multiple benefits. First, it brings focus to your observing. Taking the time to make notes on what you see rather than just glancing at your favorite objects…

As the final month of the year begins, early evenings offer just one nakedeye planet. Fortunately for us, that lone world is Saturn. The ringed planet lies high in the northwest as twilight fades, tucked among the faint background stars of northeastern Aquarius the Water-bearer. Saturn shines at 1st magnitude, brighter than any nearby star but noticeably fainter than it was at opposition in September. That’s partly due to its greater distance from Earth, but more so to the narrowing tilt of its rings. At opposition, the ring system tilted 1.8° to our line of sight; in mid-December, that value falls to 0.6°. When the rings appear wide open, as they will in 2031 and 2032, Saturn reaches magnitude –0.5, some 2.5 times brighter than it does this year. A…

Intelligent life? The Dyson spheres described in Seth Shostak’s cool article about detecting alien life (“Can we detect alien artifacts?”, May 2025) reminded me of an idea that I recall from Intelligent Life in the Universe by Carl Sagan and Iosif Shklovsky. If the matter in our solar system could be rearranged into a sphere around our Sun at the orbit of Earth, a lot more people could be accommodated. I wonder how such a sphere would appear across the galaxy. – Eric Reines, Marblehead, MA Remembering Yerkes Thank you for the excellent article “The rebirth of Yerkes” in the June issue. It brought back wonderful memories of my astronomy classes at Sam Houston State University in the early 1970s with Marjorie Hall Harrison. Every now and then, Dr. Harrison…

The Artemis Accords are a series of nonbinding international agreements intended to coordinate exploration of the Moon and beyond, fostering peaceful uses of the solar system’s resources. NASA’s Artemis Accords website (www.nasa.gov/artemis-accords) introduces the concept in its preamble: “With many countries and private companies conducting missions and operations around the Moon, the Artemis Accords provide a common set of principles to enhance the governance of the civil exploration and use of outer space.” The framework of the Accords hearkens back to the United Nations’ Outer Space Treaty of 1967 and other such international space law treaties. Its guidelines seek to avoid potential conflict or misunderstanding in upcoming industrial space activities like mining, manufacturing, energy generation, and scientific exploration. The Artemis Accords highlight the commitment by the U.S. and the other…

ORIONID METEORS Active dates: Oct. 2–Nov. 7 Peak: Oct. 21 Moon at peak: New Maximum rate at peak: 20 meteors/hour THE ORIONID METEOR SHOWER peaks Oct. 21, although it is active between Oct. 2 and Nov. 7. This annual event is renowned for its swift, bright meteors that radiate from the constellation Orion, near the star Betelgeuse. Under optimal conditions — clear, dark skies and minimal light pollution — viewers can expect up to 20 meteors per hour in the predawn hours when the radiant is high in the sky. The radiant rises in the east before midnight and reaches its highest point in the sky around 5:30 A.M., making the early-morning hours ideal for observation. This year the New Moon on Oct. 21 ensures dark skies, enhancing visibility. To fully…

FALLING STEEPLY into the Sun’s gravity well, Comet C/2025 A6 (Lemmon) drops in from the Oort Cloud for a brief two-month visit. By month’s end it peaks around 8th magnitude, comparable to Messier galaxies, in the northwest and is accessible to 3-inch scopes from a country location. Discovered in January by D.C. Fuls with the Mount Lemmon Survey in Arizona, this mile-sized ball of dirt and ice is headed to a point half the Sun-Earth distance before shooting back out. Skip October’s first two weeks, then get ready to jump. As darkness descends, Comet Lemmon is not much more than 20° high and sinks quickly into the horizon haze. Visual observers should note its position in a star field, then again 30 minutes later to see that it’s shifted 1∕6…

Sharp view Tele Vue Optics Chester, New York The 5.5mm Nagler Type 7 eyepiece offers sharpness and correction across the entire field of view. It contains seven lens elements, presents an 82° apparent field of view, and weighs 20.7 ounces (587 grams). It is designed with comfort in mind for eyeglass wearers, with 19mm of eye relief. The eyepiece comes in both 1¼" and 2" models. $635.00 1-845-469-4551 https://televue.com Protect and serve Celestron Torrance, California Celestron’s Padded Telescope Bag for 6" RASA has an outer layer of 900-denier polyester surrounding a 1½-inch-thick (38 millimeters) layer of EPE foam. It has a built-in pocket to store the telescope’s filter drawer and camera adapter. It weighs 4 pounds (1.8 kilograms) and measures 19.25 by 7.1 by 7.1 inches (489 by 180 by…

This rich, vibrant image brimming with glowing gas and scattered stars shows the Trifid and Lagoon nebulae (M20 and M8, respectively). It was among the first photos released by the National Science Foundation–U.S. Department of Energy Vera C. Rubin Observatory on June 23. The Trifid Nebula, named for the three lobes separated by the dark dust lanes of Barnard 85 that intersect at its center, is located at upper right. The much larger Lagoon Nebula, a well-known starforming region, glows to its lower left, taking up the lower portion of the image. Both nebulae are located some 5,200 light-years away in the constellation Sagittarius. The galactic plane, where most of the stars, dust, and gas of the Milky Way reside, runs through this region, resulting in cosmic views you feel…

ONE OF THE MOON’S enduring mysteries is that while it has no global magnetic field today, Apollo samples and spacecraft measurements have revealed lingering magnetism in rocks and large surface regions — evidence of ancient magnetism 10 times stronger than the Moon’s small core could have produced. Intriguingly, some of the strongest magnetic anomalies are antipodal — positioned on the exact opposite side of the Moon — to major impact basins like Crisium, Imbrium, Orientale, and Serenitatis. In a May 23 paper published in Science Advances, a team led by Issac Narrett at MIT proposed that asteroid impacts could have created globe-spanning plasma clouds that temporarily amplified magnetic fields on the other side of the Moon. Using cloud computing, Narrett’s team modeled cataclysmic asteroid impacts, finding that they could create…

IT’S EASY TO FOLLOW dwarf planet 1 Ceres, sliding across the back of Cetus the Whale. In just five minutes, you can step onto the balcony or deck, swing one binocular field east of the midpoint between Saturn and the lonely but bright Beta (β) Ceti below, and note which dot is a trespasser. Use the string of four Phi [ϕ] stars to anchor yourself. Place those in a logbook and add a few faint stars where Ceres ought to be, and by month’s end you’ll have a chain (that’s Ceres’ movement each day). At opposition on the 2nd, Ceres glows at magnitude 7.6, then fades gradually to 8.0. With a telescope you can see it move in an hour relative to background stars on the 8th, 13th, and 28th.…