Table of contents for January 2023 in Astronomy

“OF ALL THE HEAVENLY BODIES, comets are assuredly those whose appearance strikes most forcibly the attention of mortals,” wrote French astronomer Camille Flammarion in his book Popular Astronomy (1894). And, for as long as humans have looked toward the sky, it’s been true. Comets have both terrified and amazed us. This was never more apparent in modernity than in 1910. Comet 1P/Halley, better known as Halley’s Comet, had last been visible in 1836 and would grace the heavens again that spring. The comet’s return was highly anticipated, so imagine everyone’s surprise when a brilliant comet unexpectedly appeared months earlier. The object that would become known as both the Great January Comet of 1910 and the Daylight Comet was first seen Jan. 12 in the Southern Hemisphere. It’s unclear who precisely…

JANUARY 2023 Long winter nights Early winter sunsets offer nice evening views of the planets, starting with Mercury and Venus. Mercury quickly drops away, only to reappear in the morning sky before the end of the month. Venus is dazzling in the west and later in the month has a close encounter with Saturn, a stunning sight in small telescopes. Mars and Jupiter dominate the evening sky and the Red Planet is occulted by the Moon for observers in the southern U.S. Uranus and Neptune wander among fainter stars but are easy targets for binoculars or small scopes. Let’s begin on the evening of Jan. 1. Mercury is the first planet to set, within an hour of the Sun. Look with binoculars 6° due west of Venus 20 minutes after…

OVER THE LAST FEW YEARS, we have been fortunate to be treated to several dramatic comets gracing our skies. Comets C/2020 F3 (NEOWISE) and C/2021 A1 (Leonard) were both wonderful objects to observe and image, with NEOWISE being one of the most impressive naked-eye comets of the 21st century. The timing of recent comets couldn’t be better from an imaging standpoint, either. Since their introduction decades ago, digital cameras have grown steadily in popularity and prevalence, so that nearly every amateur astronomer now has one — and the accompanying improvements in light sensitivity has made image processing easier than ever before. Plus, thanks to smartphones, pretty much everyone is equipped with a camera that is good enough to catch shots of these brief visitors from the outskirts of our solar…

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We welcome your comments at Astronomy Letters, P.O. Box 1612, Waukesha, WI 53187; or email to letters@astronomy.com. Please include your name, city, state, and country. Letters may be edited for space and clarity. Stellar examples Compliments on the August 2022 issue, especially the excellent articles “Capturing the Moon in high res” by Leo Aerts and Klaus Brasch, and “The star that changed the cosmos” by Rod Pommier. Both stories describe exactly the adventures I seek when I roll my rig outside and pray for clear skies. —Bruce de Graaf, Northborough, MA Erratum In “Scopes for city-dwellers” from the August 2022 issue, the “Exit pupil” illustration on page 31 incorrectly showed the light leaving the eye lens as a parallel beam. In actuality, the image continues to draw to a focus…

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. January 1 8 P.M. January 15 7 P.M. January 31 Planets are shown at midmonth MAP SYMBOLS Open cluster Globular cluster Diffuse nebula Planetary nebula Galaxy STAR MAGNITUDES Sirius 0.0 1.0 2.0 3.0 4.0 5.0 STAR COLORS A star’s color depends on its surface temperature. • The hottest stars shine blue • Slightly cooler stars appear white • Intermediate…

COMETS PROVIDE PHOTOGRAPHERS with endless possibilities. They are dynamic close-up subjects: capable of shifting their form from night to night, sprouting nebulous comae, and even undergoing outbursts. Comets are also itinerant photobombers, regularly crossing paths with familiar deep-sky objects as they glide elliptically against the celestial sphere. And when great comets graze the Sun and unleash their tails across the entire sky, they make for spectacular wide-field vistas. Where once these landscapes were captured only in sketches and paintings, the steady march of technology has enabled astroimagers to record them in increasingly stunning photographs. The images here capture some of the great (and nearly great) comets of the past six decades. Mark Zastrow is a senior editor of Astronomy. As a child, his first great comet was Hale-Bopp, but what…

LUCKY ARE THOSE who have seen a great naked-eye comet, one with a head and tail so intense that you need only look up to see it. It’s a rarity: On average, such a comet — brighter than magnitude 0 — appears once every 15 years. Fortunately, several fainter comets that are visible through binoculars or small-to medium-sized telescopes grace the skies each year. To many, hunting down and monitoring these fuzzy, frozen fragments left over from the formation of our solar system is one of the most satisfying pastimes of our hobby, linking us to celestial sights that have influenced humanity throughout the ages. And for those wishing to get into the exciting pursuit of observing comets, here’s what you need to know. Start a comet watch Most serious…

GREAT COMETS ARE FIXTURES throughout astronomical history. They pop up unexpectedly and can change the way people see the skies, creating unforgettable experiences that can inspire and live on in our collective memory. Typically, astronomers denote a comet as “great” if it reaches easy naked-eye visibility. It helps if the comet can be seen for a long time, as was the case with Comet Hale-Bopp (C/1995 O1), but even a comet only visible for a few days can be great if it’s bright enough. The most recent great comet was Comet McNaught (C/2006 P1). Readers familiar with my stories know that I love lists. So, when asked to choose the greatest comets in recent history, I thought, “Oh, what fun that will be!” The big question was how far back…

HALLEY PLIES THE MILKY WAY For the past 37 years, Comet 1P/Halley has been edging its way ever deeper into the solar system. Now well beyond the orbit of Neptune, history’s most famous comet will start its long journey back toward the Sun in late 2023. It will make its closest approach to both the Sun and Earth in July 2061, when it should reach 2nd magnitude among the dim background stars of the northern constellation Lynx. Observers will be in for a fine show — perhaps even better than during its 1986 appearance. This image shows Halley in March of that year against the backdrop of eastern Sagittarius, with the bright glow of the central Milky Way to its west. (North is to the right in this view.)…

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. March 1 9 P.M. March 15 8 P.M. March 31 Planets are shown at midmonth MAP SYMBOLS Open cluster Globular cluster Diffuse nebula Planetary nebula Galaxy STAR MAGNITUDES Sirius 0.0 1.0 2.0 3.0 4.0 5.0 STAR COLORS A star’s color depends on its surface temperature. • The hottest stars shine blue • Slightly cooler stars appear white • Intermediate…