The year 2023, like every other one before it\u2014and, no doubt, every year to come\u2014has had its crests of good news and its troughs of bad tidings. But one constant, reliable source of awe and beauty is the sky over our head. After journeys of mere seconds to billions of years, the light from astronomical objects in the cosmos rains down on all of us, and scientists have patiently photographed some of it to better understand the universe in which we live.<\/p>\n
And every year we see new things, or old things in new ways, and I\u2019ve been set the wonderful task of selecting my favorites and relaying them and their import to you. End-of-year lists, especially those displaying astronomical imagery, tend to be splashy and colorful. That\u2019s understandable, but what they sometimes miss are the more subtle photographs, those that hide momentous discoveries in minor visual details or offer fresh perspectives on familiar objects. They may not leap off the page, but they still have an impact.<\/p>\n
That\u2019s what I\u2019ve kept in mind while sorting through this year\u2019s celestial treasure trove. This gallery is by no means complete, but it shows what I think are some of the most interesting astronomical portraits to have emerged in 2023.<\/p>\n
The Macabre Glow of Galactic Bones<\/h2>\n
No gallery such as this would be complete without something from the James Webb Space Telescope (JWST), our newest infrared eye on the sky. This monster observatory has already brought so many small revolutions to astronomy that picking one from the past year is no small task. Should it be a baby star throwing an immense tantrum<\/a> or a massive old star shedding material at colossal rates<\/a> before it inevitably explodes as a supernova? Or should it be a map of a mind-stomping 100,000 galaxies<\/a>?<\/p>\n Well, how about something very, very different\u2014such as the skeletal structure of a nearby galaxy\u2019s intricate web of dust<\/a> (as seen in the opening image above)?<\/p>\n Messier 51 (M51) is a spiral galaxy about 30 million light-years away that is face-on when viewed from Earth. A favorite of amateur and professional astronomers, it has a beautiful spiral structure and shows the effects of a smaller galaxy colliding with it. In the phenomenally sharp and decidedly eerie false-color view from JWST\u2019s Mid-Infrared Instrument, shown above, we see countless clouds of cosmic dust in a skeletonlike pattern. Each of these clouds is made up of small grains of rocky and sooty carbon-based molecules expelled by dying stars. M51\u2019s rotational motion combines with its complex gravitational field to sculpt these collective dust clouds into interconnected whorls; red areas show regions where dust is warmed by starlight, and yellow hues denote sites of active star formation. Astronomers captured this image to better understand how stars are born in stellar nurseries and how they evolve over time.<\/p>\n NASA\u2019s Lucy spacecraft is currently in the main asteroid belt, cruising by its way to Jupiter\u2014or, more accurately, to Jupiter\u2019s orbit. Lucy\u2019s mission is to study several asteroids sharing the huge gas giant\u2019s orbit around the sun<\/a>. Each asteroid has been nudged into position by a balance of Jupiter\u2019s gravity and that of our star. The Lucy mission\u2019s targets are called Trojan asteroids, and they\u2019re leftovers from the early days of the solar system, like fossils of earlier times\u2014hence Lucy\u2019s moniker. It\u2019s named after the eponymous Australopithecus afarensis<\/em> fossil skeleton found in Africa in the 1970s.<\/p>\n As a way to test its navigational and imaging system on its way to the planet, the spacecraft was aimed to fly past a main belt asteroid. Known as Dinkinesh\u2014the Ethiopian name for the Lucy fossil\u2014this space rock is only about 800 meters across. Astronomers had been puzzled about the asteroid\u2019s brightness fluctuations as seen from Earth, which were explained when Lucy saw that Dinkinesh had a moon<\/a>! Such companions aren\u2019t uncommon for asteroids, so while this was a surprise, it wasn\u2019t exactly shocking.<\/p>\n But then astronomers were, in fact, shocked to find they were seeing double: the moon itself is made up of two rocks just touching<\/a>, called a contact binary! This is the first time anyone has seen a contact binary moon orbiting an asteroid moon like this, and theorists are already busy trying to figure out how it formed. What other secrets will this wonderfully named spacecraft see as it flies past more relics from our deepest planetary prehistory?<\/p>\n Bennu is a potentially hazardous asteroid, a half-kilometer-wide space rock that has a cumulative 0.06 percent chance of hitting Earth two centuries from now. I\u2019ll take those odds, but I\u2019m also glad NASA also sent the OSIRIS-REx mission there to investigate.<\/p>\n Among its many mission goals, OSIRIS-REx was tasked with gathering samples of the material on and just beneath Bennu\u2019s surface, most of which is thought to have scarcely changed in the eons since the asteroid\u2019s formation near the dawn of the solar system. Bennu is thus a rocky time capsule from those bygone epochs, and scientists suspect other asteroids like it may have helped seed Earth with life\u2019s essential ingredients shortly after our planet cooled. After a long, long journey, the flying-saucer-shaped sample return container, with its horde of Bennu bits, landed in the Utah desert in September 2023<\/a>.<\/p>\n Scientists hoped to collect about 60 grams of material but may have actually captured several hundred. Exactly how much they have is still uncertain; two of the 35 fasteners holding the lid on the container are stuck, so mission personnel cannot fully open the apparatus. Engineers are working on making tools that can open it all the way.<\/p>\n Even so, the researchers were able to use tweezers to retrieve a small amount of the material inside, and together with stray asteroidal material that dusted the container\u2019s exterior, they already have more than 70 grams to study. That\u2019s more than enough for scientists to get an early taste of OSIRIS-REx\u2019s cosmic bounty, and they\u2019ve already found that the sample brought back from Bennu is rich in water and carbon alike<\/a>. Ironically, this asteroid is showing us how its kind may have helped deliver life to our planet, even as they threaten it.<\/p>\n Comet C\/2020 V2 (ZTF) never got closer than about 280 million km from Earth, so it never brightened enough to be seen with unaided eyes. It was nonetheless a dramatic sight in telescopes, especially to expert astrophotographer Damian Peach<\/a>. He waited until December 12, 2023, to take this shot<\/a>, when the comet was moving through the constellation Grus (the Crane) and passing by three lovely spiral galaxies called NGC 7582, 7590 and 7599. This coincidental positioning frames all these objects perfectly.<\/p>\n It also gives us an uncanny sense of depth. At the time that Peach took this image, the comet was 500 million km from Earth<\/a>. That\u2019s a decent distance inside our own solar system, but it\u2019s a much shorter distance than that of the background stars, which are quadrillions of kilometers farther away.<\/p>\n And that brain-melting distance is positively crushed by the gap between us and the three galaxies, which are around 70 million light-years away: that\u2019s about 700 quintillion (700,000,000,000,000,000,000) km! The universe is deep<\/em>.<\/p>\n Incidentally, the comet\u2019s orbit is what\u2019s called hyperbolic, meaning it has too much energy to be bound by the sun\u2019s gravity. V2 is likely to escape the solar system entirely and slowly make its way into interstellar space. In a few million years it may very well be cruising the interstellar gulfs between the stars.<\/p>\n Globular clusters are vaguely spherical collections of hundreds of thousands of stars all held together by their mutual gravity. They remind me of swarms of bees frozen in a snapshot by the way that the myriad stars buzz around their cluster\u2019s center. More than 150 of these clusters orbit our Milky Way galaxy<\/a>, most many tens of thousands of light-years away. But some are close enough to Earth that they\u2019re visible to the naked eye.<\/p>\n At about 15,000 light-years away, Terzan 12 is too dim to be a naked-eye globular cluster. And its dimness isn\u2019t caused by distance alone: it\u2019s located very close in the sky to the Milky Way\u2019s center, so we only see it through nearly opaque intervening clouds of cosmic dust.<\/p>\n One way to help pierce that veil to is to look for infrared light, which can pass through dust better than visible light can. Hubble Space Telescope has cameras that can detect infrared light (though not as well as JWST can), and its sharp vision picks the stars of Terzan 12 out of the murk<\/a>.<\/p>\n Even then, though, the clouds aren\u2019t smooth but patchy, and some thicker ones still manage to block Hubble\u2019s view of the cluster\u2019s left side. Stars there appear redder because the longer light\u2019s wavelength is, the better it reaches us through that miasma. Observations such as this not only teach us about the star cluster but also about the density and location of the dusty fog lying near the Milky Way\u2019s heart.<\/p>\n In Chile\u2019s Atacama Desert, at a gasp-inducing elevation of 3,046 meters above sea level atop the mountain Cerro Armazones, the European Southern Observatory is building the world\u2019s largest optical telescope, aptly (if somewhat prosaically) named the Extremely Large Telescope<\/a>, or ELT. Upon completion in 2028, its primary mirror<\/a> will be an array of 798 hexagonal mirrors, each 1.5 meters across, working in concert within an accuracy of a few dozen nanometers to create a single reflecting surface spanning an incredible 39 meters.<\/p>\n For right now, though, while the telescope is being fabricated, so, too, is its massive dome. Eighty meters tall\u2014the height of a 24-story building\u2014and 88 meters across, the protective enclosure is still under construction.<\/p>\n But that doesn\u2019t mean it\u2019s too early for amazing photographs of the ELT. Situated on the peak of Cerro Paranal 33 km away, a photographer caught the sun rising behind what will soon be a 6,100-ton behemoth<\/a>.<\/p>\n This is a tricky shot because the azimuth (cardinal direction) of the sunrise changes every day, and getting the right alignment between the two mountains and our much more distant star on the horizon took exacting timing. This photograph was taken on August 29, 2023. Cranes frame the dome\u2019s silhouette, and a few sunspots dot the face of the rising sun. Despite this promising dawn, the future isn\u2019t necessarily bright for other projects to build similarly sized observatories: The difficult engineering and high cost of ELT may make it one of the last of overwhelmingly large ground-based telescopes humans ever build<\/a>.<\/p>\n On April 20, 2023, the moon passed directly between Earth and the sun, blocking our star from view to select observers in the Southern Hemisphere\u2014a total solar eclipse. From Earth, the moon appeared as a dark disk as its shadow swept across the southern Indian and Pacific Oceans.<\/p>\n But what did it look like from the moon? <\/em>The Japanese company ispace<\/a> built a mission called HAKUTO-R<\/a> that entered lunar orbit on March 21, 2023. The company deployed a lander that, unfortunately, was lost moments before its final descent to the surface. Just days earlier, however, it saw something no human has yet witnessed in person: the eclipsing shadow of the moon sweeping across the face of Earth from 380,000 km away.<\/p>\n The moon\u2019s gray, crater-pocked and forbidding surface dominates the view of the image, but our eyes are drawn inexorably to the mottled blue disk near the lunar limb (edge of the moon\u2019s surface). Some white clouds can be seen, as well as brown splotches that are in reality Australia and part of Asia.<\/p>\n But look again: that dark discoloration marring Earth\u2019s face near Australia is the shadow of the moon, cast back all that distance across space to intersect our planet\u2019s surface, giving so many people the thrill of a lifetime in the form of a total solar eclipse.<\/p>\n We don\u2019t yet have a proper name for this unique perspective. When the moon blocks the sun as seen from Earth, it\u2019s a solar eclipse. When Earth blocks the sun as seen from the moon, we call it a lunar eclipse. But what do we call a view from the moon as its shadow sweeps across Earth\u2014a \u201cterrestrial eclipse\u201d?<\/p>\n With human exploration of the moon advancing, we\u2019ll need to nail that down. Or maybe we can just wait a little while; one day, maybe not too far in the future, people will experience this phenomenon for themselves. Perhaps we should leave the naming to them.<\/p>\n Jupiter is so big that it defies our puny human minds. Its diameter is 11 Earths wide, and more than 1,000 Earths would be needed to fill its volume. Its atmosphere is so deep that there\u2019s no real solid surface; we only see its cloud tops. From Earth, Jupiter\u2019s wide horizontal stripes that mark the gas giant\u2019s atmospheric storms are a familiar sight to anyone who has peered through even a small telescope.<\/p>\n Earth and Jupiter orbit the sun in very nearly the same plane, and Jupiter\u2019s axis is tipped a mere three degrees from perpendicular. This orientation has kept details of Jupiter\u2019s poles hidden from us\u2014that is, until NASA sent the formidable Juno spacecraft to orbit the gas giant.<\/p>\n Armored like a tank to shield it from Jupiter\u2019s powerful magnetic fields, which accelerate charged particles to electronics-zapping energies, Juno is on a long, looping orbit that takes it from 8 million km above the cloud tops to just 4,200 km in altitude, where it speeds full tilt past Jupiter at 200,000 km per hour.<\/p>\n These breathtaking plunges send the spacecraft swooping over higher latitudes near Jupiter\u2019s north pole, revealing sights unseen from Earth. In April, on its 50th pass<\/a> over the planet, it took this shot of two huge cyclones whirling together<\/a>. (Juno\u2019s raw images from the pass were processed by software engineer Kevin M. Gill<\/a>.)<\/p>\n Those cyclones are part of an octet of regularly-spaced vortices surrounding Jupiter\u2019s pole, each more than 1,000 km wide, with a single central, larger cyclone sitting smack-dab on the pole that\u2019s about 4,000 km wide. It\u2019s not clear how these cyclones formed or why they\u2019re stable; models of Jupiter\u2019s atmosphere predict they should dissipate. But there they are, telling us that there are more things in the heavens than are dreamed of in our philosophy.<\/p>\n Clearly it\u2019s up to us to dream bigger.<\/p>\nAn Asteroid\u2019s Moon Doubles Down<\/h2>\n
![\"the](\"https:\/\/static.scientificamerican.com\/sciam\/assets\/Image\/2023\/2023-ASTRO-IMAGES-2_dinkinesh-firstlook-llorri.jpg?w=900\")
<\/a>The Locked Time Capsule of the Solar System\u2019s Past<\/h2>\n
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<\/a>The Near, the Far and the Very, Very Far<\/h2>\n
![\"Comet](\"https:\/\/static.scientificamerican.com\/sciam\/assets\/Image\/2023\/2023-ASTRO-IMAGES-4_-c2020v2_2023_12_12dp.jpg?w=900\")
<\/a>Dusty View of a Cosmic Beehive<\/h2>\n
![\"Image](\"https:\/\/static.scientificamerican.com\/sciam\/assets\/Image\/2023\/2023-ASTRO-IMAGES-5_52830827448_0a4caa8953_o.jpg?w=900\")
<\/a>Bright Dawn, Big Telescope<\/h2>\n
![\"colorful](\"https:\/\/static.scientificamerican.com\/sciam\/assets\/Image\/2023\/2023-ASTRO-IMAGES-6_STScI-01H7TERFRBB47TB1X56AQT0J60.jpg?w=900\")
<\/a>A View of a Solar Eclipse\u2014From the Moon<\/h2>\n
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<\/a>Storms as Large as Worlds<\/h2>\n
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<\/a>