This year, we heard the low hum of gravitational waves criss-crossing the cosmos, observed a "ring of fire" solar eclipse, and applauded the arrival of asteroid samples. And, even as the James Webb Space Telescope and several solar system explorers continue to shape the science of astronomy, amateur astronomers and their ever at-the-ready scopes are making significant contributions.

Here are Sky & Telescope's picks for the top news stories in astronomy this year.

1. Detection of the Gravitational-Wave Background

Illustration of a supermassive black hole binary system
Illustration of a supermassive black hole binary system.
NASA's Goddard Space Flight Center / Scott Noble

The top news story of the year might also be its most esoteric. In an ingenious technique developed over decades, astronomers used the signals from pulsars all across the Milky Way to look for the infinitesimal squeezing and stretching of space due to criss-crossing ripples in spacetime. And this year, they finally found it: A low and quiet hum of gravitational waves, probably coming from supermassive black hole binaries near and far.

2. October's Annular Solar Eclipse Dazzles Americas

Cloudy partial eclipse
The eclipse as momentarily seen from Eugene, Oregon. Photo by Tahoe Mack,

Sky & Telescope editors and contributing editors reported on the annular solar eclipse of October 14th from locations across the U.S. and Mexico. Observers across Americas felt the temperature drop, heard birds grow restless, watched light turn an eerie silver, and then watched as the Moon briefly centered itself in the Sun's blazing disk. As Editor in Chief Peter Tyson put it: "Something awesome was taking place and we were gratefully there to witness it."

Now we're anticipating the next eclipse, this one the total solar eclipse on April 8, 2024.

3. JWST Turns Up Unexpected Results in Early Universe

Black field spotted with galaxies
JWST's Near-Infrared Camera took this image of the same region of sky covered in the Hubble Ultra Deep Field, revealing distant, early galaxies.
NASA / ESA / CSA / STScI / C. Williams (NSF's NOIRLab). Image processing: J. DePasquale (STScI).

At an astronomy conference that opened the year, astronomers announced a surprising find in James Webb Space Telescope data: The early universe seemed to host more and bigger galaxies than astronomers had expected, calling into question either our understanding of galaxy formation, of dust formation, or of cosmology itself. While some initially doubted the extreme distances of the galaxies involved, results published later in the summer backed them up. Understanding what it all means awaits another year . . .

4. Asteroid Sample Return, Plus Lucy's Double-Surprise Flyby

Bennu sample return capsule on the ground in the desert, red-white parachute behind
A capsule with a sample of asteroid Bennu inside, delivered to Earth on Sept. 24, 2023, by NASA’s OSIRIS-REx mission, is seen shortly after touching down on the Department of Defense’s Utah Test and Training Range.
NASA / Keegan Barber

On September 24, 2023, a capsule from NASA's Osiris-REX mission returned pieces of the asteroid 101955 Bennu safely to Earth. NASA’s first collection of a pristine asteroid sample was so successful that at first scientists had some trouble even accessing the sample. But study is now well underway to understand the role of carbonaceous chondrite asteroids in Earth's formation.

Dinkinesh and its contact-binary moon
One of Lucy's later images shows the asteroid Dinkinesh not only has a satellite, but its satellite is a contact binary — the first time a contact binary has been seen orbiting another asteroid.
NASA / Goddard / SwRI / Johns Hopkins APL

That wasn't the only big asteroid news of the year. In a bonus on November 1st, NASA's Lucy flew by the first asteroid of its mission. Images downlinked to Earth turned up a double surprise — not only did 152830 Dinkinesh have a moon, its moon was itself a contact binary.

5. A Re-Forecast for the Sun's Activity

Plasma flies fast and furious from the sun, some of it raining back down along magnetic field lines
A powerful X-class flare and CME erupted from near the Sun's limb on March 7, 2011. NASA/SDO

Observers and scientists alike have been noticing that the number of sunspots, solar eruptions, and aurorae are more numerous than expected from a 2019 forecast. In response to the unexpected activity, the Space Weather Prediction Center has issued a new, experimental forecast, which predicts an earlier, stronger peak in the Sun's activity — now roughly coinciding with the the April 8, 2024, total solar eclipse!

6. Attention on Light Pollution

Light pollution map for North America
The World Atlas view of North America shows light pollution is strongest in the eastern half. But light pollution is also creeping up on observatories in the western half. (Explore light pollution all over the globe.)
Esri / HERE / Garmin / FAO / NOAA; Source: Airbus / USGS / NGA / NASA / CGIAR / NLS / OS / NMA / Geodatastyrelsen / GSA / GSI / GIS User Community

A number of results on artificial light at night — both on the ground and in our skies — have gained the public's attention this year. Among them, a study found that light pollution is increasing even faster than we thought it was, while another study found that not even remote observatories are safe.

Satellites, too, are a growing problem for the Hubble Space Telescope, for radio observatories, and a particularly bright one known as BlueWalker 3 could severely affect even the most casual observers. It's not all bad news, though: SpaceX's Starlink company is making efforts to mitigate their satellites' brightness, and they're working. Larger policy changes may also help other companies follow suit.

7. Scientists Finally Find Active Volcanism on Venus

Sulphur-tinged volcano rises above surface on Venus
This computer-generated 3D model of Venus's surface shows the summit of Maat Mons. One of the vents on Maat Mons appears to have enlarged and changed shape in 1991, as seen in Magellan data.
NASA / JPL-Caltech

After decades of searching, scientists have finally found a clear sign of active volcanism on Venus. A new analysis of decades-old data from NASA's Magellan orbiter caught a change in the shape and depth of an apparently active caldera. We've long known that volcanism has completely resurfaced Venus in the recent past; now, we finally have evidence that it's still happening. The find will also inform future missions, which will know better what to look for when they arrive at our secretive sister planet.

8. Successful Launches and Moon Landings

Chandrayaan 3
The first surface image received from Chandrayaan 3. ISRO

Three nations attempted to land on the Moon this past year, and one succeeded: India's Chandrayaan 3 set down in the lunar south pole on August 23rd. Russia's Luna 25 lander and Japan's Hakuto R lander crashed, however.

Meanwhile, three successful launches marked a great year for planetary science and astronomy in space. NASA's Psyche mission is now on its way to a metallic asteroid, ESA's JUICE mission is en route to Jupiter, and another just-launched ESA mission, Euclid, is already returning spectacular first images.

9. No Atmosphere on Exoplanets Trappist-1b and c

Artist's illo of airless TRAPPIST-1c and red dwarf star host in background
This artist’s concept shows what the hot rocky exoplanet TRAPPIST-1 c could look like.
NASA / ESA / CSA / Joseph Olmsted (STScI)

The promising septuplet system of rocky planets around the nearby red dwarf star Trappist-1 disappointed this year, with two sets of JWST data turning up no air at all on Trappist-1b and only a small chance of atmosphere on Trappist-1c. However, even if both inner planets end up being airless, that doesn't spell doom for the system as a whole. Time will tell what Webb will find for the five more temperate outer planets.

10. Amateur Contributions to Astronomy

Supernova fireworks
The unusual fireworks-like structure of nebula Pa 30 may result from the merger of two dying stars.
Robert Fesen

This was an especially active year for amateur astronomers contributing to science. In 2023 amateurs helped uncover a strange supernova, aided the tracking of asteroids Didymos and Dimorphos following the DART probe's crash, found another asteroid's moon, noticed new dwarf galaxies, provided insight into Venus's atmosphere, and even discovered a glowing green arc near Andromeda that still defies explanation.

Click through the links above to read about each of these incredible amateur contributions! Even more results are incoming, as amateur astronomers recently contributed to a rare occultation of Betelgeuse on December 12th — those observations await analysis.

Honorable Mentions

Image of PDS 70b and a possible Trojan body(ies)
This millimeter-wavelength image shows the young planetary system PDS 70, located 370 light-years from Earth. The system features a star (at center) and a protoplanet, PDS 70b (solid yellow circle). The protoplanet's orbit is indicated by a solid yellow ellipse. On the same orbit, astronomers have detected a cloud of debris (yellow dotted line) that could be the building blocks of a new Trojan planet (or the remnants of one already formed) that shares b's orbit. (Another planet, not circled, is PDS 70c at 3 o’clock, right next to the inner rim of the disk.)
ALMA (ESO / NAOJ / NRAO) / Balsalobre-Ruza et al. / Astronomy & Astrophysics 2023

While big results become big news, sometimes it's the cosmic oddballs that garner attention. We thought these particular oddities (in no particular order) were worthy of note in this year's round-up. Click the links to learn more about what makes these objects odd, and important too.

What's your pick for top stories of the year? Tell us in the comments below.


Image of Lou


December 27, 2023 at 8:36 pm

There's been so much awesome news this year (as happens every year!) that it's so hard to pin down my favorites, but I'd pick the gravitational-waves detection, proto-planet found in gap, massive early galaxies not so massive after all, and volcanism confirmed on Venus. Thanks very much for all your efforts in reporting these stories and cutting through the hype surrounding them!

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Image of Lindsay


December 29, 2023 at 5:59 pm

Please tell me again why the bar in spiral galaxies cannot be composed of two merging black holes.

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Image of Andrew James

Andrew James

December 30, 2023 at 9:54 pm

...OK. It is a matter of scale. Distance between any merging black holes is about 50-100 million kilometres or less. A galaxy bar like a Milky Way is about 30,000 light years or 9.461 trillion kilometers times 30,000. Moreover, bars are primarily formed due to gravitational instabilities in the galactic disk not the core. Masses of black holes in spiral galaxies are simply too small to generate the gravitational disturbances required to form bars. Processes take billions of years before a merger occurs, but bars can be created much quicker.

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Image of Andrew James

Andrew James

December 30, 2023 at 10:03 pm

My pick would be ESA 2023 launching the Euclid space telescope.

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