The eROSITA telescope has released its second great catalogue of the X-ray sky with close to two million sources across half the sky, roughly double what it published before. Buried in it is a result from Bonn that matters more than the headline number. A team there went after the faintest part of a massive galaxy cluster, the outer region where fresh material is still arriving along threads of gas stretching between clusters. Nobody had measured that emission before. The gas turns out to be hotter, denser and poorer in heavy elements than the models say it should be.

Blazars are galaxies with a jet aimed almost directly at us, and they flicker across every part of the spectrum at once. Almost everything we think we know about them comes from short observing campaigns just a handful of days, every year or two, in one narrow band of energy. A Polish and German team has now done the opposite, following a single blazar for nearly twenty years with two orbiting observatories and in two observations from 2012 they found something in the spectrum that nobody had predicted.

Reading the atmosphere of another world means catching starlight as it filters through that planet's air during a transit. The signal is about one part in a million and a true Earth twin transits only once a year, so you cannot simply repeat the measurement until the noise averages away. Each attempt has to work on its own. A team led from Shanghai has proposed the alternative to building an impossibly large mirror in space - nine hundred, one metre telescopes, flying together, watching the same transit and analysing the light together.

Scientists using the Daniel K. Inouye Solar Telescope (DKIST) in Hawai'i have found a mechanism occurring on the Sun's surface that they think is heating our star's outer atmosphere. The process, called a Kelvin-Helmholtz Instability (KHI), could well be the root cause of a phenomenon called flux braiding that builds up and moves around on the Sun and heats the coronasphere. This discovery may well also explain the fundamental physics of similar activity at other stars.

The surface of the Moon is a bleak and forbidding place that might be hiding a lot of water ice on and under the dusty landscape. However, most possible ice deposits don't just stand out in an image. You need specialized mapping to find traces of water ice. So, scientists have devised another way to find the Moon's frosty hidden reserves. They use seismic waves from moonquakes as locator beacons.

Lujendra Ojha, a planetary scientist, led a study suggesting that Europa’s icy shell may be a stronger barrier between the moon’s hidden ocean and its surface than previously thought.

A snowflake cannot form out of nothing. Water vapour will sit in the air quite happily, supercooled and reluctant, until it finds a speck of dust to build on and then it crystallises around it. Cosmochemists have had a version of that problem for decades. The early Solar System was a furnace of gas, and the first solid grains had to condense out of it somehow, yet condensing from a perfectly uniform gas is slow and difficult work. New research from Caltech, analysing fragments of a meteorite that fell over Mexico in 1969, suggests the seeds were already there. Buried inside the oldest solids we possess are specks of stardust from a star that lived and died before the Sun existed.

Hunting for dark matter usually means building something enormous and burying it — a tank of liquid xenon in a mine, a magnet the size of a lorry, decades of engineering and a great deal of money. A team in Japan have just done it differently. They realised that the Earth's own magnetic field is larger than any magnet we could ever construct, and that the gap between the ground and the ionosphere behaves as a natural resonating cavity, ringing at around eight cycles per second. If dark matter is what some theorists suspect, it should leave a faint hum in that cavity. So they went looking, not with a new instrument, but in ten years of geomagnetic readings already recorded at a quiet observatory in Dumfriesshire in Scotland.

Ask what lies inside a black hole and the honest answer has always been a bit of a shrug and something about a singularity, a point where density becomes infinite and physics stops being able to tell you anything at all. It is the most unsatisfying answer in astrophysics, second only perhaps to what happened before the Big Bang. Now two theorists in China have produced a solution in which something else sits inside the horizon entirely, a neutron star, whole and intact, twelve kilometres across, its interior perfectly well behaved and apparently defying the laws of physics.

Astronomers were fortunate when the Einstein Probe detected the difficult-to-observe initial shock break out (SBO) from a supernova. The SBO is the first electromagnetic indication that a star is going to explode, and by observing it and the aftermath, researchers were able to determine what type of progenitor star exploded, and what it's pre-explosion environment was like.

Exoplanets need to be habitable for a long time for complex life to develop. To sustain habitability, exoplanets need to retain their atmospheres. But many exoplanets are exposed to extreme ultraviolet light and coronal mass ejections that can strip atmospheres away. A new mission aims to understand these processes and help exoplanet scientists identify exoplanets that can stay habitable for meaningful lengths of time.

Sure. It may not look like much. But sometimes, the 'wow' factor in an image lies in knowing just what you're seeing. While most of us are eagerly awaiting Wednesday’s total solar eclipse across the North Atlantic and Spain, robotic emissaries on the Martian surface have recently given us a look at an astronomical occlusion of a different sort, as Phobos crossed in front of Earth.

Tracking the debris orbiting at high velocity in space is only going to get harder over time. We have ground-based radar systems, such as the Space Fence, designed to detect pieces down to around 10 cm. But finding objects smaller than that, which can still cause a lot of damage traveling at 17,000 miles per hour, requires completely new thinking. One potential solution is a new idea from Dr. David Smith of Duke University, who was recently funded for a NASA Innovative Advanced Concepts (NIAC) Phase I grant to build robotically assembled electromagnetic metamaterials for long-range space situational awareness.

In-situ Resource Utilization (ISRU) is going to be a critical technical component of any human expansion out into the solar system. Our first challenge with utilizing those resources, though, is finding them. We know how, at least in theory - send a probe to an asteroid, or a particular part of the Moon, and take a sample, maybe analyze that sample with some spectrographs, or send it back to Earth to be poked and prodded. The problem with this methodology is simple - it’s expensive. Sending dedicated probes to every near-Earth asteroid, or every potentially interesting site near a lunar base is prohibitively expensive. So a new NASA Institute for Advanced Concepts (NIAC) grant explores a different opportunity - using a single, relatively small spacecraft to visit multiple ISRU locations, and figure out their composition from tens of kilometers away.

A quasar is a supermassive black hole in the act of feeding, and it’s so bright that it drowns out the galaxy it sits in. That is a nuisance if you want to weigh the galaxy and weighing it is exactly what you need to do to understand how black holes and the host galaxies grew up together. There is a way round it however, catch a quasar whose galaxy happens to be bending the light of something further away, and the bending betrays the mass. The catch is that such alignments are vanishingly rare, and the survey that might contain them holds 800,000 quasars. A team at Ohio State set a neural network on the pile and it came back with seven.

Mars has plenty of water, and almost all of it is in the wrong place. The poles are rich in ice, the equator, where you would actually want to land, has none within reach. That leaves the mid-latitudes, and until now the honest answer about what lies beneath them has been a bit of a shrug. Two new studies from the Planetary Science Institute have changed the shape of that answer. Rather than simply asking whether the data are consistent with buried ice, they have started calculating the odds and can now say, of a given patch of Martian ground, that there is a 64 per cent chance of finding ice if you dig there.

Time on a large professional telescope is one of the scarcest resources in science. Astronomers wait months for a few hours, and every one of those hours is a running argument with the weather, the Moon and the atmosphere. Point at the wrong target at the wrong moment and the data comes back soft, washed out, or useless, with the next chance half a year away. A team has now handed that argument to a machine. Their system was trained not on the rules astronomers use but on what astronomers actually did, night after night, for years.

With the end of the Space Age and the winding down of the Cold War, scientists again returned to the question of interstellar flight. Having failed to realize a working concept that could be realized in the near term, more exotic ideas began to be considered, reflecting further breakthroughs in theoretical physics.

Ancient Maltese seafarers had both a complex cosmology and likely at least rudimentary skills in celestial navigation. It's thought that they used stars in the southern constellation of Crux to make their way around the south-central Mediterranean.

NASA MAVEN (Mars Atmosphere and Volatile Evolution) mission scientists have uncovered a key puzzle piece in understanding certain types of auroras on Mars, finding that they form in a similar way to Earth-based auroras.