For about a century, scientists have known that the Universe is in a state of constant expansion. In honor of the scientists who definitively showed this, this expansion has come to be known as the Hubble Constant (or Hubble-Lemaitre Constant). Today, scientists use two main techniques to measure the rate of expansion: the Cosmic Microwave Background (CMB) and the Cosmic Distance Ladder. The former relies on redshift measurements of the CMB, the relic radiation left over from the Big Bang, while the latter relies on parallax and redshift measurements using variable stars and supernovae (aka "standard candles").
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When most people think of a supernova, they're thinking of a Type II core-collapse supernova. These are massive stars that have reached the end of their time on the main sequence. They've used up their supply of hydrogen and continue fusing heavier elements until the star can't support its own mass. The core collapses and they explode, outshining their entire host galaxy for months.
On April 8th, 2024, people across the world witnessed a solar eclipse, a relatively rare event in which the Moon occults (blocks out) light from the Sun. To capture this event, volunteers at 143 observatories across the U.S. trained their equipment on it as part of NASA's Eclipse Megamovie citizen science project. The images they took were groundbreaking and provided some of the most detailed images to date of the Sun's corona. After nearly two years of production and editing, the Eclipse Megamovie team has released the dataset from this project.
Anyone familiar with the search for alien life will have heard of the “Goldilocks Zone” around a star. This is defined as the orbital band where the temperature is just right for liquid water to pool on a rocky planet’s surface - a good approximation for what we thought of as the early conditions for life on Earth. But what happens if that life doesn’t stay on an Earth analog? If they, like we, start to move towards their neighboring planets, the idea of a habitable zone becomes much more complicated. A new paper from Dr. Caleb Scharf of the NASA Ames Research Center, and one of the agency’s premier astrobiologists, tries to account for this possibility by introducing the framework of an Interplanetary Habitable Zone (IHZ).
It's strange that a dying star is at the heart of this glowing cloud of gas, ionizing it and lighting it up almost like a living structure, but that's Nature for you. An aging Wolf-Rayet star, which has exhausted its hydrogen core, illuminates the Cat's Eye Nebula from within. The star, catalogued as HD 164963, has suffered episodic mass loss as it ages. Each complex layer in the gaseous nebula represents one episode of mass loss driven by the star's extremely powerful winds.
One feature of the Solar System that doesn't require a complex explanation is the cratered surfaces of some of the planets and moons. These surfaces have been pummeled by impacts, and on some bodies, these impacts are defining features. The craters tell the tale of our Solar System's history.
Additive manufacturing, also known as 3D printing, has a proven track record for reducing waste and efficiently producing made-to-order tools and components. For years, NASA has been testing the technology aboard the International Space Station (ISS) to investigate how it may increase astronauts' self-sufficiency. This is especially true of missions far from Earth, where opportunities for resupply are few and far between. With their latest experiment, the JPL Additive Compliant Canister (JACC), NASA demonstrated another application: 3D printing space antennas.
The stable Solar System we see around us today took time to develop. Not only did it take time for planetary orbits to stabilize, but planetary atmospheres also needed time to evolve. In fact, planetary orbits and evolving atmospheres work together to determine what a solar system eventually looks like, and photoevaporation drives the process.
Ever since physicist Freeman Dyson first proposed the concept in 1960, the “Dyson sphere” has been the holy grail of techno-signature hunters. A highly advanced civilization could build a “sphere” (or, in our more modern understanding, a “swarm” of smaller components) around their host star to harvest its entire energy output. We know, in theory at least, that such a swarm could exist - but what would it actually look like if we were able to observe one? A new paper available in pre-print on arXiv, and soon to be published in Universe from Amirnezam Amiri of the University of Arkansas digs into that question - and in the process discloses the types of stars that are the most likely to find them around.
Red dwarfs make up the vast majority of stars in the galaxy. Such ubiquity means they host the majority of rocky exoplanets we’ve found so far - which in turn makes them interesting for astrobiological surveys. However, there’s a catch - astrobiologists aren’t sure the light from these stars can actually support oxygen-producing life. A new paper, available in pre-print on arXiv, by Giovanni Covone and Amedeo Balbi, suggests that they might not - when it comes to stellar light, quality is just as important as quantity. And according to their calculations, Earth-like biospheres are incredibly difficult to sustain around red dwarfs.
Superliminous supernovae are miraculous events. For astronomers, they also provide a vital tool for measuring cosmic distances and the rate at which the Universe is expanding. As part of the Cosmic Distance Ladder, these incredibly bright stellar explosions are the "standard candles" for objects billions of light-years away. In a rare event, researchers from the University of Munich, using the Large Binocular Telescope (LBT) in Arizona, witnessed a superluminous supernova 10 billion light-years away that was far brighter than most explosions of its kind.
Satellite imaging is increasingly important to every field from crop monitoring to poverty reduction. So it’s no surprise that there have been more and more satellites launched to try to meet that growing demand. But with more satellites comes more risk for collision - and the debris field that comes after the collision. A new paper in Advanced in Space Research from John Mackintosh and his co-authors at the University of Manchester looks at how we might use mission design to mitigate some of the hazards of increasing the number of satellites even more.
Aging stars are prolific producers of dust, and the dust plays an important role in the cosmos. Their dust is ejected into the interstellar medium (ISM) where it is taken up in the next generation of stars and planets. This is how stars seed their environments with metals, elements heavier than hydrogen and helium, which are necessary for rocky planets and life to form.
It is one of the most famous questions in science, and it was asked, as legend has it, over lunch. Enrico Fermi, the physicist who helped build the first nuclear reactor and whose name graces a unit of length so small it makes an atom look generous, was chatting with colleagues about the possibility of alien life when he suddenly asked ‘where is everybody?’
When the Apollo astronauts returned from the Moon, they brought back something more valuable than any treasure, 382 kilograms of Moon rock that would keep scientists busy for generations. For decades those samples have been scrutinised, measured, and debated and, for decades one question has refused to be satisfactorily answered… Did the Moon once have a powerful magnetic field or was it always magnetically feeble?
Through the Artemis Program, NASA hopes to establish a permanent human presence on the Moon in its southern polar region. China, Russia, and the European Space Agency (ESA) have similar plans, all of which involve building bases near the permanently shadowed regions (PSRs) - i.e., craters that contain water ice - that dot the South Pole-Aitken Basin. For these and other agencies, it is vital that these bases be as self-sufficient as possible since resupply missions cannot be launched regularly and take several days to arrive.
You could fit about a dozen of them across the full stop at the end of this sentence. Under a microscope they look like tiny eight legged bears shuffling around in slow motion. They have been frozen, boiled, irradiated, sent into the vacuum of open space and brought back alive. Scientists have been studying them for over two hundred years and they still have the capacity to astonish. Their name is tardigrade, though most people know them by the rather more charming nickname of water bears. And right now, they might be one of our best tools for figuring out how to survive on Mars.
Something arrived in our Solar System last summer that had been travelling for longer than the Earth has existed. It came from somewhere out there in the dark between the stars, possibly from a planetary system that formed billions of years before our own Sun even ignited. We don't know exactly where it came from. We may never know. But for a brief, extraordinary window of time, this ancient wanderer passed close enough to study, and the world's astronomers dropped almost everything to watch.
In the summer of 2023, something happened that engineers had talked about for decades but few genuinely expected to see in their lifetimes. SpaceX's Starship, a stainless steel tower taller than a thirty storey building lit its thirty three engines simultaneously and lifted off from the Texas coast. It did not go entirely to plan. But it went. And when the Super Heavy booster returned in flight test five to be caught, mid air, by the enormous mechanical arms of its own launch tower, it was clear that the rules of spaceflight had fundamentally changed.
In the future, farmers on the Moon and Mars will have a big challenge: how to grow healthy food in two extremely unhealthy environments. That's because the soil on both worlds isn't at all hospitable to plants and animals. Neither are other conditions. Both are irradiated worlds, Mars has a thin atmosphere and the Moon has none at all. So, how will future colonists on either world grow their food?
It's been about 8 months since the Vera Rubin Observatory (VRO) saw first light. Now the telescope is scanning the night sky to detect transient changes and sending alerts to astronomers and observatories around the world so they can perform follow-up observations. This alert system is one of the last milestones before the VRO starts its primary endeavour: the decade-long Legacy Survey of Space and Time (LSST).

