Tabla de contenidos para December 2024 en Astronomy

We live in a world that often is not fair. Sometimes justice takes quite a while to arrive, and other times it never material-izes at all. One such saga has been brewing in the world of astronomy for a very long time. In the fall of 1923, a young astronomer in Pasadena, California, Edwin Hubble, made a groundbreaking image of the Andromeda “Nebula,” as it was then called. This was the first key to both the nature of galaxies and the vast cosmic distance scale. Six years later, Hubble published a landmark paper that laid out how the universe is expanding, a milestone moment in the history of science. But as historical stories often turn out to be, it’s not quite as simple as we read in our schoolbooks. It…

LIKE THE MILKY WAY, the Andromeda Galaxy (M31) is a spiral marked by winding arms. These are regions where star birth and death run rampant, from glowing stellar nurseries to exploding supernovae. Together, these factors create the glowing red clouds of hydrogen gas recently revealed by the Hubble Space Telescope, whose Advanced Camera for Surveys and Wide Field Camera 3 combined to offer researchers a glimpse at what’s going on in our near neighbor. By using the powerful space telescope to peer into M31’s arms, researchers can not only learn more about its stellar population and life cycle, but also use the galaxy as an analogue for more distant galaxies, whose stars we cannot resolve.…

MOST PEOPLE ASSOCIATE the discovery that faraway galaxies are receding from us — and thus, that the universe is expanding — with Edwin Hubble, thanks to his landmark 1929 paper. It was one of the most fundamental discoveries in the history of science. But Hubble did not discover the expansion. In the 1910s, a Lowell Observatory astronomer named Vesto Slipher found that spiral nebulae, as galaxies were called, are “fleeing” from us at what were then unheard-of speeds. This was the first observational evidence of the expanding universe. Hubble’s paper established a linear relationship between Slipher’s nebulae velocities and the distances Hubble had measured — a relation that later became known as Hubble’s law — but failed to cite Slipher’s own publications containing his indispensable measurements or even to mention his…

TWO MAJOR METEOR SHOWERS occur in December. The Geminids are active between Dec. 4 and 20, and peak late on Dec. 13. A nearly Full Moon on the peak night interferes strongly with this shower. Some Geminids are particularly bright, and will show up in a moonlit sky, although much lower rates than those advertised will be experienced. More favorable this year are the Ursids, with a peak coinciding with a Last Quarter Moon. The Ursids are active between Dec. 17 and 26, and peak early on the 22nd. The radiant, located in Ursa Minor, is visible all night. The Moon rises around local midnight, so late-evening observing will offer dark skies. However, rates are low, with no more than a halfdozen to a dozen meteors visible in an hour period.…

TO WATCH THE END of Comet C/2023 A3 (Tsuchinshan-ATLAS)’s story, be prepared at the eyepiece 90 minutes after sunset. Dropping to the horizon and out of easy binocular range, 8thmagnitude Tsuchinshan-ATLAS demands a country sky to the west with a clear horizon. Its diatomic carbon emission shuts down near December’s end due to increasing distance from the Sun. The celestial snowball floats in front of the dust cloud LDN 642 on the 9th and 10th. Visually, the comet will draw your attention to star clusters NGC 6755 and 6756 as December opens. Try different magnifications and sweep around. These sparse groupings aren’t at all cometlike, so swing to nearby globular NGC 6760 to compare shape, brightness profile, and edge softness with Tsuchinshan-ATLAS. When the evening dark window reopens on the…

In 1874, James Nasmyth and James Carpenter published a remarkable book: The Moon: Considered as a Planet, a World, and a Satellite. Lavishly illustrated with spectacular images of lunar features based on their own observations and exquisite plaster models, it served as a platform for the authors to advance their views on the nature and evolution of the lunar surface. In a book review from the same year, British astronomer Sir Joseph Norman Lockyer wrote: "The illustrations to this book are so admirable, so far beyond those one generally gets of a celestial phenomenon, that one is tempted to refer to them first. No more truthful or striking representations of natural objects than those here presented have ever been laid before his readers by any student of Science; and may…

Universal manual Penguin Random House New York, NY The beauty and science of space combine in the book Smithsonian Atlas of Space. This 400-page hardback, created by NASA’s Chief Historian Roger D. Launius, features illustrations, maps, and images detailing humanity’s understanding of the universe from ancient times to modern day. It also includes profiles of some of astronomy’s greatest minds. $60.00 penguinrandomhouse@ penguinrandomhouse.com www.penguinrandomhouse.com Double focus Sharpstar Optics/Askar Jiaxing, China The Askar SQA55 Quintuplet Refractor is the latest offering for those looking to do daytime photography and astrophotography. The refractor includes five lenses along with a field flattener for accurate and sharp photos. It also includes a dual-speed focuser with fine and coarse adjustment. $795.00 support@sharpstar-optics.com www.sharpstar-optics.com Combined system ZWO Suzhou, China The ASI2600MC Air combines an autoguider with an…

Thousands of galaxies populate the rich Coma Cluster. This vast collection of island universes spans some 20 million light-years and lies 320 million lightyears from Earth in the constellation Coma Berenices. The cluster served as a great laboratory for Swiss astronomer Fritz Zwicky, who in 1933 discovered that its luminous matter had far too little mass to gravitationally bind the cluster. He coined the term dark matter for the invisible material that keeps the galaxies under control. Ninety years later, astronomers aren’t much closer to solving the mystery of dark matter. Yet that doesn’t take anything away from the cluster’s visual splendor. Smaller galaxies crowd around the supergiant ellipticals NGC 4889 (center) and NGC 4874 (above it) that dominate the cluster’s core.…

As February begins, Venus appears low in the western evening sky. The brilliant planet stands nearly 15° high an hour after the Sun goes down and dominates the faint background stars of Pisces the Fish. Although the inner world lies a healthy 45° east of the Sun, it doesn’t climb high because the ecliptic — the apparent path of the Sun across the sky that the planets follow closely — makes a shallow angle to the western horizon after sunset at this time of year. And, unfortunately, Venus dips closer to the horizon as the month progresses. But not even twilight can keep the brightest planet down. Venus reaches greatest brilliancy at midmonth, when it shines at magnitude –4.9 — fully 10 times brighter than its nearest competitor, Jupiter. This…

HOW TO USE THIS MAP This map portrays the sky as seen near 30° south latitude. Located inside the border are the cardinal directions and their intermediate points. To find stars, hold the map overhead and orient it so one of the labels matches the direction you’re facing. The stars above the map’s horizon now match what’s in the sky. The all-sky map shows how the sky looks at: 10 P.M. February 1 9 P.M. February 15 8 P.M. February 28 Planets are shown at midmonth MAP SYMBOLS Open cluster Globular cluster Diffuse nebula Planetary nebula Galaxy STAR MAGNITUDES STAR COLORS A star’s color depends on its surface temperature. The hottest stars shine blue Slightly cooler stars appear white Intermediate stars (like the Sun) glow yellow Lower-temperature stars appear orange…

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CHINA’S STARLINK The first batch of 18 satellites for the Qianfan (“thousand sails”) communications megaconstellation launched Aug. 6 from Taiyuan Satellite Launch Center in northern China. Plans call for an eventual total of more than 14,000 satellites. CAUGHT SPEEDING Citizen scientists and a team of astronomers have found a star just 0.08 times the mass of the Sun traveling at 1 million mph (1.6 million km/h) — fast enough to escape the Milky Way. The object, 400 light-years distant, is the smallest such galactic runaway yet known. O2 SANS SUNLIGHT Rare-metal seafloor rocks called polymetallic nodules may be producing oxygen from seawater through electrolysis, says a July 22 report in Nature Geoscience. If confirmed, this “dark oxygen” has implications for life on worlds with subsurface oceans like Enceladus and Europa.…

HOW TO USE THIS MAP This map portrays the sky as seen near 35° north latitude. Located inside the border are the cardinal directions and their intermediate points. To find stars, hold the map overhead and orient it so one of the labels matches the direction you’re facing. The stars above the map’s horizon now match what’s in the sky. The all-sky map shows how the sky looks at: 9 P.M. December 1 8 P.M. December 15 7 P.M. December 31 Planets are shown at midmonth MAP SYMBOLS Open cluster Globular cluster Diffuse nebula Planetary nebula Galaxy STAR MAGNITUDES STAR COLORS A star’s color depends on its surface temperature. The hottest stars shine blue Slightly cooler stars appear white Intermediate stars (like the Sun) glow yellow Lower-temperature stars appear orange…

RISING IN THE NORTHEAST along with Jupiter during the evening hours, asteroid 15 Eunomia slides through object-rich central Auriga while outshining most of the background stars. Peaking at magnitude 8.1, about the brightest it can possibly get, Eunomia is a straightforward target to follow across the fainter outer spiral arm of the Milky Way. In fact, none of the stars in the splashy star cluster M36 (less than a degree to the south) are brighter. On the 7th, Eunomia shares a medium-power field with the reflection nebula/mini-cluster combo NGC 1931, one of the sky’s best comet lookalikes. The 18th is the best night to see the space rock move relative to the background, sliding less than 10' from 16 Aurigae, which shines at magnitude 4.5. An 8th-magnitude field star to…

The constellation Taurus the Bull is an easy one to find in the Northern Hemisphere’s fall and winter skies. It stands opposite the Sun at the beginning of December. The head of the figure is a large V of stars, and standing out among them is the ruddy 1st-magnitude star Aldebaran (Alpha [α] Tauri) marking one of its eyes. This star, along with Antares in Scorpius, Fomalhaut in Piscis Austrinus, and Regulus in Leo, were the four Royal Stars of ancient Persia. If you’re new to constellation identification, the best way to locate Taurus is to wait until the easily recognized constellation Orion the Hunter rises into view. Then, using the three stars that mark Orion’s belt, draw a line upward, and you’ll arrive at Aldebaran. A bit of stellar…

THE MOON is Earth’s nearest neighbor and the only celestial object humans have visited. Because of its changing position relative to the Sun and Earth, the Moon appears to go through phases, from a slender crescent to Full Moon and back. The best times to observe our satellite through a telescope come a few days on either side of its two Quarter phases. For the best detail, look along the terminator — the line separating the sunlit and dark parts. VENUS dazzles in the evening sky from New Year’s Day until mid-March. It then vanishes in the Sun’s glare for two weeks, returning to view before sunrise in late March. The inner planet remains a morning object until it gets too close to the Sun in late November. Venus appears highest…

Beginning in late November during the waning phases of the Moon, and then again in late December, you can investigate the possibility of a curious optical phenomenon. It involves a bright planet passing by a large and diffuse star cluster visible with the naked eye. On the evening of June 13, 2023, I went out as twilight faded to observe the conjunction of Venus with the Beehive open star cluster (M44). Shining brilliantly at magnitude –4.2, Venus sailed within 1° of the cluster. Under a dark sky, the Beehive appears to the unaided eye as a diffuse, 4thmagnitude glow spanning 95' of sky. When darkness fell, I could see both Venus and the Beehive with direct vision. Unsurprisingly, when I looked at them with averted vision, the Beehive appeared to…

THE STRAIGHT WALL is the best-known scarp feature on Luna’s frontside, an outstanding treasure in the form of a long black blade extending outward from its bejeweled hilt. It is perfectly placed on relatively flat lava near the center of a large, half-buried crater on the southern third of the Moon, appearing just after First Quarter. Find this fault in the terrain on Dec. 8 just north of the bright highlands that include magnificently rayed Tycho. Although its very name conjures images of a cliff, in fact the Straight Wall has a modest slope between 12° and 20° — a decent grade for driving, but not enough for tobogganing. Officially labeled as Rupes Recta in many lunar atlases, it is 75 miles long and rises some 1,300 feet above the plain.…

It may be cold this month, but now is a great time to get outside and explore Jupiter’s beauty and might. The fifth planet will not only reach opposition on Dec. 7, it will also be at perigee (closest to Earth) on Dec. 6, putting on its biggest and brightest show of the year. Known for its Great Red Spot, Jupiter also boasts four bright, fast-moving moons: giant Ganymede, cratered Callisto, volcanic Io, and icy Europa. And there’s no better time to brave the cold and explore some of the Galilean moons’ most exciting events: transits, occultations, eclipses, and shadow transits! Transits occur when one of the moons moves across the face of Jupiter. As the moons have orbital periods of just a few days, transits occur hundreds of times…

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