Enlarge / The star's orbit, shown here in light, is influenced by the far more massive black hole, indicated by the red orbit. (credit: ESO/L. Calçada )

As far as black holes go, there are two categories: supermassive ones that live at the center of the galaxies (and we're unsure about how they got there) and stellar mass ones that formed through the supernovae that end the lives of massive stars.

Prior to the advent of gravitational wave detectors, the heaviest stellar-mass black hole we knew about was only a bit more than a dozen times the mass of the Sun. And this makes sense, given that the violence of the supernova explosions that form these black holes ensures that only a fraction of the dying star's mass gets transferred into its dark offspring. But then the gravitational wave data started flowing in, and we discovered there were lots of heavier black holes, with masses dozens of times that of the Sun. But we could only find them when they smacked into another black hole.

Now, thanks to the Gaia mission , we have observational evidence of the largest black hole in the Milky Way outside of the supermassive one, with a mass 33 times that of the Sun. And, in galactic terms, it's right next door at about 2,000 light-years distant, meaning it will be relatively easy to learn more.

Enlarge / Artist's visualization of GRB 221009A showing the narrow relativistic jets—emerging from a central black hole—that gave rise to the brightest gamma-ray burst yet. detected. (credit: Aaron M. Geller/Northwestern/CIERA/ ITRC&DS)

In October 2022, several space-based detectors picked up a powerful gamma-ray burst so energetic that astronomers nicknamed it the BOAT (Brightest Of All Time). Now they've confirmed that the GRB came from a supernova, according to a new paper published in the journal Nature Astronomy. However, they did not find evidence of heavy elements like platinum and gold one would expect from a supernova explosion, which bears on the longstanding question of the origin of such elements in the universe.

As we've reported previously , gamma-ray bursts are extremely high-energy explosions in distant galaxies lasting between mere milliseconds to several hours. There are two classes of gamma-ray bursts. Most (70 percent) are long bursts lasting more than two seconds, often with a bright afterglow. These are usually linked to galaxies with rapid star formation. Astronomers think that long bursts are tied to the deaths of massive stars collapsing to form a neutron star or black hole (or, alternatively, a newly formed magnetar ). The baby black hole would produce jets of highly energetic particles moving near the speed of light, powerful enough to pierce through the remains of the progenitor star, emitting X-rays and gamma rays.

Those gamma-ray bursts lasting less than two seconds (about 30 percent) are deemed short bursts, usually emitting from regions with very little star formation. Astronomers think these gamma-ray bursts are the result of mergers between two neutron stars, or a neutron star merging with a black hole, comprising a "kilonova." That hypothesis was confirmed in 2017 when the LIGO collaboration picked up the gravitational wave signal of two neutron stars merging, accompanied by the powerful gamma-ray bursts associated with a kilonova.

Enlarge (credit: NASA/JPL-Caltech/University of Arizona )

Mars has a history of liquid water on its surface, including lakes like the one that used to occupy Jezero Crater , which have long since dried up. Ancient water that carried debris—and melted water ice that presently does the same—were also thought to be the only thing driving the formation of gullies spread throughout the Martian landscape. That view may now change thanks to new results that suggest dry ice can also shape the landscape.

It’s sublime

Previously, scientists were convinced that only liquid water shaped gullies on Mars because that’s what happens on Earth. What was not taken into account was sublimation , or the direct transition of a substance from a solid to a gaseous state. Sublimation is how CO ₂ ice disappears ( sometimes water ice experiences this, too).

Frozen carbon dioxide is everywhere on Mars, including in its gullies. When CO ₂ ice sublimates on one of these gullies, the resulting gas can push debris further down the slope and continue to shape it.

Enlarge / The Dark Energy Spectroscopic Instrument (DESI) has made the largest 3D map of our universe to date. (credit: Claire Lamman/DESI collaboration)

An international collaboration of scientists has created the largest 3D map of our universe to date based on the first results from the Dark Energy Spectroscopic Instrument (DESI). It's an impressive achievement, with more to come, but the most significant finding stems from the collaboration's new measurements of dark energy. Those results roughly agree with the current prevailing theoretical model for dark energy, in which dark energy is constant over time. But there are some tantalizing hints that it could vary over time instead, which would call for some changes to that prevailing model.

Granted, those hints are still below the necessary threshold to claim discovery and hence fall under the rubric of "huge, if true." We'll have to wait for more data from DESI's continuing measurements to see if they hold up. In the meantime, multiple papers delving into the technical details behind these first results have been posted to the arXiv, and there will be several talks presented at a meeting of the American Physical Society being held this week in Sacramento, California, as well as at Rencontres de Moriond in Italy.

“Our results show some interesting deviations from the standard model of the universe that could indicate that dark energy is evolving over time,” said Mustapha Ishak-Boushaki , a physicist at the University of Texas, Dallas, and a member of the DESI collaboration. “The more data we collect, the better equipped we will be to determine whether this finding holds. With more data, we might identify different explanations for the result we observe or confirm it. If it persists, such a result will shed some light on what is causing cosmic acceleration and provide a huge step in understanding the evolution of our universe.”

Enlarge / Trying out the robot on a glacier. (credit: NASA/JPL-Caltech )

Icy ocean worlds like Europa or Enceladus are some of the most promising locations for finding extra-terrestrial life in the Solar System because they host liquid water. But to determine if there is something lurking in their alien oceans, we need to get past ice cover that can be dozens of kilometers thick. Any robots we send through the ice would have to do most of the job on their own because communication with these moons takes as much as 155 minutes.

Researchers working on NASA/JPL’s technology development project called Exobiology Extant Life Surveyor (EELS) might have a solution to both those problems. It involves using an AI-guided space snake robot. And they actually built one.

Geysers on Enceladus

The most popular idea to get through the ice sheet on Enceladus or Europa so far has been thermal drilling, a technique used for researching glaciers on Earth. It involves a hot drill that simply melts its way through the ice. “Lots of people work on different thermal drilling approaches, but they all have a challenge of sediment accumulation, which impacts the amount of energy needed to make significant progress through the ice sheet,” says Matthew Glinder, the hardware lead of the EELS project.