In the span of a human lifetime, much of the Universe seems unchanging. But that’s an illusion; things are always changing, and that fact can make galaxies and the clusters they reside in very unruly places due to mergers and collisions.
Nuclear fusion is at the center of stellar evolution. Most of a star’s life is a battle between gravity and nuclear power. While we understand this process on a broad scale, many of the details still elude us. We can’t dive into a star to see its nuclear furnace, so we rely on complex computer simulations. A recent study has made a big step forward by modeling the entire fusion cycle of a single element.
Asteroid impacts have arguably killed off more species than almost any other type of disaster since life began on Earth. The most famous of these, the Chicxulub impactor, killed the dinosaurs about 65 million years ago, along with 76% of all species on the planet at the time. But that was by no means the worst disaster; as far as we can tell, it wasn’t even the biggest asteroid. That title currently goes to the Vredefort crater in South Africa. Coming in at over 300 kilometers wide, it was the largest asteroid crater so far found, at least when it was formed about 2 billion years ago. But that might be about to change if a theory from Andrew Glikson and Tony Yeates of New South Wales is correct. They have found what they believe to be the biggest impact crater on Earth since the Late Heavy Bombardment in their own Australian province of New South Wales, and they think it might have caused one of the other five mass extinction events.
In case you missed it, the weather’s been hot. From warmer-than-usual temperatures in northern climes to melting ice sheets in the polar regions, July 2023 was a record-breaking month. That’s not just some random perception. NASA has been keeping records and the agency confirms what most of us have observed for ourselves. It was a warm one.
It is a scientific certainty that Mars was once a much different place, with a denser atmosphere, warmer temperatures, and where water once flowed. Evidence of this past is preserved in countless surface features, ranging from river channels and alluvial deposits to lakebeds. However, roughly 4 billion years ago, the planet began to change into what we see today, an extremely cold and desiccated environment. Between all that, it is possible Mars experienced glacial and interglacial periods, which is evidenced by images like the one taken by the NASA Mars Reconnaissance Orbiter (MRO) shown above.
The Universe is expanding, and it’s doing so at an ever-increasing pace. Whether due to a dark energy field throughout the cosmos or due to a fundamental of spacetime itself, the cosmos is stretching the space between distant galaxies. But nearby galaxies, those part of our local group, are moving closer together. And how they are falling toward each other could tell us about the nature of cosmic expansion.
Astronomers have discovered an intense binary star system located about 1,400 light years away. It contains a brown dwarf with 80 times the mass of Jupiter which is bound closely with an incredibly hot white dwarf star. Observations have shown the brown dwarf is tidally locked to the white dwarf, allowing the daytime surface temperatures on the brown dwarf to reach 8,000 Kelvin (7,700 Celsius, 14,000 Fahrenheit) — which is much hotter than the surface of the Sun, which is about 5,700 K (5,427 C, 9,800 F). The brown dwarf’s nightside, on the other hand, is about 6,000 degrees K cooler.
The Sun dominates the Solar System in almost every way imaginable, yet much of its inner workings have been hidden from humanity. Over the centuries, and especially in the last few decades, technological advancements allowed us to ignore our mothers’ exhortations and stare at the Sun for as long as we want. We’ve learned a lot from all those observations.
Just how dark is the night sky?
One of the main objectives of the James Webb Space Telescope (JWST) is to use its powerful optics and advanced instruments to observe the earliest galaxies in the Universe. These galaxies formed about 1 billion years after the Big Bang, coinciding with the end of what is known as the “Cosmic Dark Ages.” This epoch is inaccessible for conventional optical telescopes because the only sources of photons were largely associated with the relic radiation of the Big Bang – visible today as the Cosmic Microwave Background (CMB) – or were the result of the reionization of neutral hydrogen (visible today the 21 cm line).
While many people are living through a sweltering summer, it’s the depths of winter in Antarctica. Usually, this means there’s a lot of sea ice around the continent. Yet, this year, it’s the lowest it’s ever been. What’s happening?
From June 18th to 22nd, the Penn State Extraterrestrial Intelligence Center (PSETI) held the second annual Penn State SETI Symposium. The event saw experts from many fields and backgrounds gathering to discuss the enduring questions about SETI, the technical challenges of looking for technosignatures, its ethical and moral dimensions, and what some of the latest experiments have revealed. Some very interesting presentations examined what will be possible in the near future and the likelihood that we will find evidence of extraterrestrial intelligence.
Plenty of areas in the solar system are interesting for scientific purposes but hard to access by traditional rovers. Some of the most prominent are the caves and cliffs of Mars – where exposed strata could hold clues to whether life ever existed on the Red Planet. So far, none of the missions sent there has been able to explore those difficult-to-reach places. But a mission concept from a team at Stanford hopes to change that.
At the Fermi National Accelerator Laboratory (aka. Fermilab), an international team of scientists is conducting some of the most sensitive tests of the Standard Model of Particle Physics. The experiment, known as Muon g-2, measures the anomalous magnetic dipole moment of muons, a fundamental particle that is negatively charged (like electrons) but over 200 times as massive. In a recent breakthrough, scientists at Fermilab made the world’s most precise measurement of the muon’s anomalous magnetic moment, improving the precision of their previous measurements by a factor of 2.
The Great Red Spot of Jupiter is a storm that has raged for hundreds of years. It was first observed by Gian Domenico Cassini in 1665, and except for a period between 1713 to 1830, it has been observed continuously ever since. Even if Cassini’s storm is not the one we see today, the current red spot has been around for nearly two centuries. While great storms appear now and then on Saturn and other gas planets, they don’t have the staying power of Jupiter’s great storm. Or so we thought.
The hunt for alien life and its radio signals from beyond our Solar System is still coming up dry. But, it’s not for lack of looking for possible advanced civilizations.
A few years ago, there was a panic about lithium-ion batteries that exploded and could do things like take down a jetliner. On a recent trip, an airline asked passengers to turn in any devices with batteries that had been banned because of safety concerns. These are indicators of a widely understood downside of lithium-ion batteries, ubiquitous in cell phones, laptops, and other electronic hardware – they can easily catch fire very spectacularly. However, a team at the Aerospace Company is working on an idea to turn this potentially catastrophic event into an asset – by using it to deorbit defunct satellites.
Radioisotope thermoelectric generators (RTGs) are the power plants of the interplanetary spacecraft. Or at least they have been for going on 50 years now. But they have significant drawbacks, the primary one being that they’re heavy. Even modern-day RTG designs run into the hundreds of kilograms, making them useful for large-scale missions like Perseverance but prohibitively large for any small-scale mission that wants to get to the outer planets. Solar sails aren’t much better, with a combined solar sail and battery system, like the one on Juno, coming in at more than twice the weight of a similarly powered RTG. To solve this problem, a group of engineers from the Aerospace Corporation and the US Department of Energy’s Oak Ridge National Lab came up with a way to take the underlying idea of an RTG and shrink it dramatically to the point where it could not potentially be used for much smaller missions.
Most of the comets we see in the sky were born in our solar system. They may have formed deep within the Oort cloud, and for some, it is their first visit to the inner solar system, but they are distinctly children of the Sun. We know of only two objects that came from beyond our solar system, Omuamua and Borisov. There are likely other interstellar objects visiting our solar system, we just haven’t found them. But that’s likely to change when Rubin Observatory comes online.
Multiple space agencies plan to send astronauts, cosmonauts, and taikonauts to the Moon in the coming years, with the long-term goal of establishing a permanent human presence there. This includes the NASA-led Artemis Program, which aims to create a “sustained program of lunar exploration and development” by the decade’s end. There’s also the competing Russo-Chinese International Lunar Research Station (ILRS) effort to create a series of facilities “on the surface and/or in orbit of the Moon” that will enable lucrative research.
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