There are plenty of awesome objects in the universe, made more marvelous by scientists’ ability to image and understand the laws and processes that make them possible. Each year, researchers make new observations and revisit old data that redefines what we know about how Earth, the solar system, galaxy, heck—the whole universe—came to be.
From stunning images to revelatory calculations, from black holes and neutron stars to gas clouds and gravitational lenses, here’s the best that 2024 had to offer in astrophysical discoveries and advances.
The oldest black hole ever found
In November, the European Southern Observatory’s Very Large Telescope Interferometer imaged a star 2,000 times the diameter of the Sun, located a staggering 160,000 light-years away. The star, a red supergiant in the Large Magellanic Cloud, is surrounded by a cocoon of material that researchers believe it’s shedding as it hurtles toward its ultimate fate: a brilliant supernova.
Jupiter’s plasma jets
In January, the Ingenuity helicopter took its 72nd flight on Mars. It would prove to be its last: The helicopter snapped a rotor blade clean off in an awkward landing, ending the drone’s airtime on the Red Planet. But Ingenuity’s contribution to spaceflight history cannot be overlooked. The machine achieved the first controlled, powered flight on another planet, and set the standard for future flying vehicles beyond Earth.
An asteroid, unleashed
Supernovas are the brilliant deaths of stars, flinging material into space as their cores collapse. This collapse can form a black hole—a region of spacetime with gravity so intense that not even light can escape it. In March, a team of astronomers imaged a star as it went supernova, revealing the dramatic moment in sharp relief.
The great North American solar eclipse
On April 8, the Moon eclipsed the Sun over a swath of North America, giving people across the continent a remarkable view of our immediate cosmic environment. At totality, the Sun looked like a thin ring of light surrounding the Moon, and plunged the afternoon skies into darkness. Here are some of the best photos of the eclipse.
A lava lake on a moon
To follow up on Io—Jupiter’s moons are pretty diverse, but all 95 of them deserve some recognition. In April, we published a slideshow of Jupiter’s moons, including standouts Io and Europa. Both will appear later in this round-up as particularly compelling venues for planetary science and astrobiology research.
A tempestuous solar season
In May, the Sun started spouting off. Sunspots and coronal mass ejections (CMEs) on our local star caused the Space Weather Prediction Center to issue a severe geomagnetic storm watch, its first since January 2005. Indeed, those solar flares ultimately caused remarkable auroras across Earth, seen as far south as Florida and Texas stateside. The May activity was a harbinger of more solar storms over the following months, which was not expected as the Sun approached its solar maximum.
Auroras on Mars
The increased solar activity was also a reminder that we are just one planet in a solar system. On Mars, the Curiosity rover captured evidence of auroras on the Red Planet, giving scientists an opportunity to see how such events unfold on other planets. Radiation from the solar activity caused artifacts in Curiosity’s images. The rover’s Radiation Assessment Detector measured its largest surge in radiation since the rover arrived on the planet; according to NASA, an astronaut standing on Mars’ surface would have received radiation equivalent to 30 chest X-rays from the solar outburst.
Webb’s most distant galaxy yet
In May, researchers announced the discovery of the most distant and earliest galaxy yet seen, as it existed less than 300 million years after the Big Bang. The galaxy from the Cosmic Dawn showcased the Webb Space Telescope’s ability to cut through interstellar dust to image some of the universe’s faintest and most distant—ergo, earliest—objects. The team’s analysis suggested that the galaxy’s light mostly comes from large stars, rather than material falling into a supermassive black hole.
The most distant merging quasars yet
It was a year of superlatives in cosmic observation. In June, a team of astronomers described the most distant merging quasars—bright cores of galaxies—yet known. The merging pair is the first confirmed from the Cosmic Dawn. The black holes at the core of each quasar are each about 100 million times the mass of the Sun, and the observation can help researchers model the early universe and its evolution.
A tunnel on the Moon
It probably wasn’t little green men. In July, researchers published a paper proposing that a pit crater on the Moon actually contains a tunnel. The structure is in the Moon’s Sea of Tranquility, where Apollo 11 landed in 1969. A tunnel on the Moon could be a boon to future missions to the satellite, where such a structure could protect astronauts from cosmic rays and solar radiation, as well as offer thermal stability, as temperatures on the Moon’s surface fluctuate dramatically.
Some spectacular views in astronomy
If you have some time, check out this year’s finalists for the Astronomy Photographer of the Year competition. From the surface of the Sun to the aurora over Iceland, the beautiful views of the cosmos are worth checking out. The universe is amazing when seen through space telescopes and distant orbiters, but is just as easily appreciated with a camera and two boots firmly on the ground.
The ‘Wow!’ signal demystified
In August, the Arecibo Wow! project uncovered data suggesting that a mysterious signal detected in 1977—often linked to extraterrestrial life—may have been caused by a massive cloud of hydrogen. The signal, dubbed “Wow!” after an astronomer famously scrawled the exclamation on a computer printout, could be the result of a magnetar, a highly magnetized neutron star, exciting atoms in the hydrogen cloud. It’s not aliens, but it’s a compelling theory.
Betelgeuse may have a little buddy
In September, a group of astronomers posited that the red supergiant star Betelgeuse’s strange dimming pattern could be due to a little star—a ‘BetelBuddy’ spinning around the larger object. Betelgeuse is so bright the other star cannot be seen, but the team’s theory could explain the fluctuations in light we see from the giant star, which will go supernova sometime in the not-so-distant future.
Gigantic black hole jets
Black holes sometimes spew jets of material moving at nearly the speed of light. These jets are some of the most extreme structures in the universe, and they got a little more extreme in September, when a team of researchers described the biggest-yet-known jets. The jets—part of a megastructure called Porphyrion, after a giant from Greek mythology—are 140 Milky Ways long, and could play an important role in shaping their surroundings in the universe.
Also in September, a different team found that black holes’ jets can cause stars to explode. Black hole jet research is definitely a space to watch in 2025, as researchers learn more about the way these remarkably large and energetic structures catalyze changes to their environment.
A dark matter breeding ground
The jury’s out on exactly what makes up dark matter, the approximately 27% of stuff in the universe that scientists cannot directly observe but interacts with ordinary matter gravitationally. In October, a team of researchers posited that one dark matter candidate—axions—could form clouds around neutron stars, offering a new venue for scientists to focus their searches for dark matter particles. Space telescopes like the European Space Agency’s Euclid telescope are devoted to the dark matter search, but the team’s research suggested that a space-based radio telescope would be invaluable for truly homing in on the extreme physics surrounding neutron stars.
The Arecibo collapse report
In November, a report published by the National Academies of Sciences, Engineering, and Medicine revealed the foremost cause of the Arecibo Observatory collapse. The storied observatory fell apart in December 2020, but the recent report disclosed exactly what happened: damage from Hurricane Maria was exacerbated by the decay of zinc in the telescope’s cable sockets; those combined stressors caused the cables to collapse, and the observatory’s suspended platform to collapse through the telescope’s giant dish.
Perseverance is finally out of its martian cradle
Just last week, scientists at NASA’s Jet Propulsion Laboratory announced that the Perseverance rover had successfully clambered out of Jezero Crater, where the rover landed in February 2021. Now, the rover will explore roughly four-billion-year-old rocks that could clue scientists into the formation of Mars, as well as Perseverance’s quest to find evidence of ancient microbial life.
The mystery of the universe’s expansion deepens
Last month, an “Einstein Zig-Zag” in space offered a new opportunity for astrophysicists to measure the Hubble constant, the number that describes the rate of the universe’s expansion. The trouble with the constant is that it is inconsistent; depending on how you calculate it, you get different numbers. The Einstein zig-zag—really a compound gravitational lens—could constrain the constant, by showing how the figure matches up with the cosmological model.
As long as we’re talking about gravitational lensing and the Hubble constant, it’s worth giving an honorable mention to research published in October that described a supernova that appeared three times in the arc of a gravitational lens some 3.6 billion light-years from Earth. Gravitational lenses are like windows into the universe’s more ancient past, magnifying the details of deep time for our viewing pleasure.
Something cold and wet near Uranus
Yes, you read that correctly. In October, a group of scientists concluded that Uranus’ moon Miranda may contain a liquid water ocean—or at least had one in its ancient past. The findings added another moon to the growing docket of exciting candidates for astrobiological investigation. Because liquid water is a prerequisite for life as we know it, scientists believe that reservoirs of liquid water—including subsurface oceans on moons like Miranda, or Jupiter’s Europa—are good spots to look for life.
A supercomputer’s model of the universe
Image: Argonne National Laboratory, U.S Dept of Energy
In November, scientists put the world’s then-fastest supercomputer to task simulating the universe’s conventional physics, as well as the behaviors and properties of dark matter. The supercomputer is called Frontier, and is capable of running a quintillion (one billion-billion) calculations per second.
Frontier’s simulations revealed the evolution of the universe as it expanded and how galaxies formed and moved as the universe unfurled. Frontier is no longer the world’s fastest computer—it was usurped by El Capitan in November—but the supercomputer can still add to our growing understanding of the cosmos.
