Space News & Blog Articles

As stars in the Milky Way move through space, some of them have an unexpected effect on the Solar System. Over time, one comes closer to the Sun during its orbit in the galaxy. Some of them actually get within a light-year of our star and pass through the Oort Cloud. Such close flybys can affect the orbits of the outer planets and send cometary nuclei on a long inward rush to the Sun.

Astronomer Igor Yu Potemine at the Université Paul Sabatier in France, and his colleagues decided to look for likely “close-passing” stars and so-called “Nemesis” stars. Their tool was the SIMBAD database, which contains updated stellar parallaxes and proper motions from ESA’s Gaia satellite. They found a number of possible candidates. These stars drifted through the outer Oort Cloud and then went back out to interstellar space. Their actions set off gravitational perturbations responsible for cometary visits to the inner Solar System over the past billions of years. It’s important to note that gravitational influences from the giant planets, as well as something called the “Galactic tide” can also perturb objects in the Oort Cloud. For purposes of his study, Potemine restricted his search to nearby stars as candidates for Oort Cloud disturbances.

When we look at which stars could cause a comet swarm from the Oort Cloud region, a couple of types of stellar candidates come to mind. The first is what some researchers call a “Nemesis” star. That’s the name for a still-theoretical companion star to the Sun. It’s thought to be a dwarf star that occasionally (like every 25-30 million years) passes too close to the Sun. That action sends a swarm of comets to the inner solar system. Astronomers continue to look for candidates for this solar Nemesis, although the search hasn’t identified “the one” as yet. They also look for other stars that periodically get too close to the Solar System and even pass through the inner regions of the Oort Cloud.

A comparison of the Solar System and its Oort Cloud. 70,000 years ago, Scholz’s Star and companion passed along the outer boundaries of our Solar System (Credit: NASA, Michael Osadciw/University of Rochester)

The Oort Cloud/outer solar system region is a still-largely unknown place. It’s not one monolithic cloud but several regions with populations of icy cometary bodies. The outer edge of the region could extend out 3.2 light-years away from the Sun. Inside the Oort Cloud is the Kuiper Belt, which also contains cometary bodies and a population of small worlds such as Pluto, Eris, Makemake, and others. There’s also a sort of intermediate population of cometary objects thought to exist between the Oort cloud and the Kuiper Belt, sometimes referred to as the Hills Cloud. This region may be populated with many more cometary nuclei than the actual Oort Cloud. So, there’s plenty of material “out there” for passing stars to perturb, and it’s likely many have in the billions of years that the Solar System has existed.

Can we secure our place in the Solar System? Not in any absolute sense because nature can be very unpredictable. But we can make the effort to safeguard our civilization by cataloguing potentially dangerous asteroids. An upcoming space telescope will help.

NASA’s SPHEREx (Spectro-Photometer for the History of the Universe, Epoch of Reionization, and Ices Explorer) mission will launch no later than April 2025. The orbiting telescope will conduct a two-year all-sky survey in optical and infrared light. The main focus of the mission is to gather data on more than 300 million galaxies and 100 million stars in the Milky Way. But SPHEREx will also add to our knowledge of Potentially Hazardous Objects (PHOs).

A new paper examines SPHEREx’s capabilities and how the mission can contribute to Planetary Defense (PD.) Its title is “Planetary Defense Use of the SPHEREx Solar System Object Catalog.” It’s currently in pre-print, and the lead author is Carey Lisse from the Space Exploration Sector at the Johns Hopkins University Applied Physics Laboratory.

SPHEREx “provides a unique space-based opportunity to detect, spectrally categorize, and catalogue
hundreds of thousands of solar system objects at NEOWISE sensitivities,” the authors write. NEOWISE is NASA’s successful asteroid-finding mission that just reached ten years of operation and has found over 3,000 NEOs (Near-Earth Objects). “By leveraging SPHEREx data, scientists and decision-makers can enhance our ability to track and characterize PHOs, ultimately contributing to the protection of our planet,” the authors of the new paper explain.

Among the many calamities that have struck life on Earth, asteroid impacts are the most dramatic. About 66 million years ago, an asteroid struck Earth and wiped out the dinosaurs. That asteroid was about 10 km in diameter and wreaked havoc on Earth’s biosphere at the time. The odds of another asteroid strike are never zero, and less massive impactors could still alter civilization forever. It could cause unimaginable suffering and strife.

If you think about space travel and the means of escaping the confines of the Earth then most people, currently, are likely to think about the new Artemis project and the Space Launch System. That’s not the only new development though, Blue Origin have been working on their New Glenn rocket and finally we have got a glimpse of their new offering. The rocket was finally rolled onto the launch pad at Cape Canaveral for testing to commence and we may even see a launch later this year.

Blue Origin was founded in 2000 by the founder of Amazon, Jeff Bezos. It is American aerospace manufacturer based in Washington, USA and specialises in producing rocket engines for the Vulcan rocket and manufactures satellites, spacecraft and a variety of space based tech. Securing the deal to become the second provider of the Lunar lander for Artemis project, Blue Origin has most certainly become a major player in the space industry. 

Their latest announcement came with the incredible sight of the New Glenn vehicle rolling out onto Launch Complex 36 at Cape Canaveral. This was the first glimpse the world got of their new advanced heavy-lift vehicle which promises to support a number of different commercial customer missions and NASA’s Artemis program to get humans back to the Moon.

Space lovers will perhaps recognise the name Glenn from the first American to orbit the Earth, John Glenn. It stands an impressive 98m tall (only about 12m shorter than Saturn V used by the Apollo astronauts). It has an impressive 7m payload bay which is double the volume of most commercial launch capabilities available today. I don’t know about you but I struggle to visualise what that means but to give it context, Blue Origin state that it could accommodate three school busses! 

The first stage, like the Falcon rockets, are reusable and designed to be used for at least 25 launches.  They will land on a sea-based platform almost 1,000km downrange from the launch site. As with the Falcon systems, the reusability of the first stage helps to keep costs per launch down. 

Universe Today has investigated the importance of studying impact craters, planetary surfaces, exoplanets, and astrobiology, and what these disciplines can teach both researchers and the public about finding life beyond Earth. Here, we will discuss the fascinating field of solar physics (also called heliophysics), including why scientists study it, the benefits and challenges of studying it, what it can teach us about finding life beyond Earth, and how upcoming students can pursue studying solar physics. So, why is it so important to study solar physics?

Prof Maria Kazachenko, who is a solar astrophysicist and assistant professor in the Astrophysical & Planetary Science Department at the University of Colorado, Boulder, tells Universe Today, “Solar physics studies how our Sun works, and our Sun is a star. We should understand how our home star works for various reasons. First, stars are the building blocks of our Universe.  Even we are made of stardust. Second, our Sun provides energy for life and affects our life here on Earth (space weather, digital safety, astronauts’ safety). So, to be safe we need to understand our star. Finally, the Sun is the only star where we could obtain high-quality maps of magnetic fields, which define stellar activity. To summarize, studying the Sun is fundamental for our space safety and for understanding the Universe.”

The field of solar physics dates to 1300 BC Babylonia, where astronomers documented numerous solar eclipses, and Greek records show that Egyptians became very proficient at predicting solar eclipses. Additionally, ancient Chinese astronomers documented a total of 37 solar eclipses between 720 BC and 480 BC, along with keeping records for observing visible sunspots around 800 BC, as well. Sunspots were first observed by several international astronomers using telescopes in 1610, including Galileo Galilei, whose drawings have been kept to this day.

Presently, solar physics studies are conducted by both ground- and space-based telescopes and observatories, including the National Science Foundation’s (NSF) Daniel K. Inouye Solar Telescope located in Hawai’i and NASA’s Parker Solar Probe, with the latter coming within 7.26 million kilometers (4.51 million miles) of the Sun’s surface in September 2023. But with all this history and scientific instruments, what are some of the benefits and challenges of studying solar physics?

Prof. Kazachenko tells Universe Today that some of the scientific benefits of studying solar physics include “abundant observations and many science problems to work on; benefits from cross-disciplinary research (stellar physics, exoplanets communities)” with some of the scientific challenges stemming from the need to use remote sensing, sometimes resulting in data misinterpretation. Regarding the professional aspects, Prof. Kazachenko tells Universe Today that some of the benefits include “small and friendly community, large variety of research problems relying on amazing new observations and complex simulations, ability to work on different types of problems (instrumentation, space weather operation, research)” with some of the professional challenges including finding permanent employment, which she notes is “like everywhere in science”.

Astronomers have been on the hunt for a new kind of exoplanet in recent years – one especially suited for habitability. They’re called hycean worlds, and they’re characterized by vast liquid water oceans and thick hydrogen-rich atmospheres. The name was coined in 2021 by Cambridge astronomer Nikku Madhusudhan, whose team got a close-up look at one possible hycean world, K2-18b, using the James Webb Space Telescope in 2023. In a newly accepted paper this January, Madhusudhan and coauthor Frances Rigby examined what the internal structure of hycean planets might look like, and what that means for the possibility of finding life within.

Hycean worlds are unlike anything we have seen in our own solar system, expanding the very definition of a habitable planet. They tend to be much bigger than Earth-like planets, earning them the moniker ‘mini-neptunes’. Their size makes them easier to detect than smaller rocky worlds, and their thick atmospheres give them a wider habitable zone.

Those same properties also make them ideal candidates for spectroscopic analysis, where measuring the chemical composition of the atmospheres might reveal biosignatures.

In order to tease out the potential characteristics of a habitable hycean world, Rigby and Madhusudhan used a modeling tool called HyRIS to map out possible planetary structures. They limited their models to only allow for habitable temperatures and pressures at the ocean’s surface, where the water meets the air.

Even with those strict conditions in place, the results showed a wide variety of possible internal structures. The ocean depths of a habitable hycean world could range from 10s of kilometers deep to 1000s of kilometers (for comparison, Earth’s ocean averages about 3.7km deep).

Intuitive Machines‘ Odysseus lander made space history today — becoming the first commercial spacecraft to survive a descent to the moon, and the first U.S.-built spacecraft to do so since the Apollo 17 mission in 1972. But it wasn’t a trouble-free landing.

Ground controllers had a hard time establishing contact with the robotic lander just after the scheduled touchdown time of 6:23 p.m. ET (2323 UTC). Several minutes passed, and then Intuitive Machines mission director Tim Crain reported that there was a faint signal coming from Odysseus’ high-gain antenna.

“We’re not dead yet,” he said.

A few minutes later, the IM-1 mission team decided that the signal was evidence enough that Odysseus was still operating.

“What we can confirm without a doubt is our equipment is on the surface of the moon, and we are transmitting,” Crain said. “So, congratulations, IM team, we’ll see how much more we can get from that.”

It’s a headline straight out of the movies yet the White House has recently confirmed it believes that Russia is building space-based anti-satellite weapon! There seems to be no conclusive evidence what this might be but one option may be a nuclear bomb that would indiscriminately wipe out satellites within a huge volume of space! Not only would it devastate satellites but would cause more problems down on the surface and create a whole load of space junk. 

In a statement, the National Security Council spokesperson John Kirby said that he did not believe the weapon had an ‘active capability’ yet and further went on to say he did not believe it had even been deployed. He went on to say that the White House was monitoring Russian activity and would continue to take it very seriously. 

Launching such a nuclear weapon into space would violate the 1967 Outer Space Treaty which countries of the United Nations, including Russia, signed. It prohibits putting nuclear weapons or weapons of mass destruction into space, on the Moon or on any other celestial object. Such an act would likely prompt sanctions from other nations and further compound the situation faced by Russia following its invasion of Ukraine. Note that such a device wouldn’t even actually need to be used, just deploying it into space would be sufficient to violate the Treaty. 

A spokesperson from Moscow has denied the existence of such a program suggesting it was “malicious fabrication” that has been created by the American political teams. The Kremlin went on to suggest that such a fabrication might coerce the Congress to pass a $97 billion foreign aid bill which includes $60 million for Ukraine. 

Tempting though such a nuclear device might seem to any countries wishing to unleash devastation to other nations, the impacts can be far reaching. The destruction of any object in orbit will create a whole debris field with components ranging from a few millimetres to several centimetres. At the moment, there are several hundreds of millions of pieces of space debris being tracked from Earth. The high velocity items drifting around pose a threat to other satellites still in operation and even the International Space Station which has had to apply course directions to avoid collisions. 

Supermassive black holes are messy feeders, and when they’re gorging on too much material, they can hurl high-energy jets into the surrounding Universe. Astronomers have found one of the most powerful eruptions ever seen, emanating from a black hole 3.8 billion light-years away. The powerful jets are blowing out cavities in intergalactic space and triggering the formation of a huge chain of star clusters.

The black hole is part of a massive galaxy cluster, named SDSS J1531, which contains hundreds of individual galaxies, and all these galaxies have huge reservoirs of hot gas and dark matter. Using several telescopes for multiwavelength observations — including the Chandra X-ray Observatory, the Low Frequency Array (LOFAR) radio telescope, the Atacama Large Millimeter and submillimeter Array (ALMA), the Gemini North telescope’s Gemini Multi-Object Spectrograph (GMOS), and the Very Large Array (VLA) — astronomers were able to discern that two of the central galaxies were engaged in a major merger. The merger activated the supermassive black hole in the center of one of the large galaxies, which produced an extremely powerful jet. As the jet moved through space, it pushed the surrounding hot gas away from the black hole, creating a gigantic cavity.

The merger and the resulting jets from the black hole created a remarkable and stunning chain of 19 young stellar superclusters wound the two galaxies like a string of beads.

In their paper, the astronomers said the dynamic environment of SDSS J1531 offers an excellent laboratory to study the interplay between mergers, and their multiwavelength studies allowed them to uncover the origin and evolution of the “beads on a string” star formation complex.

“We’ve reconstructed a likely sequence of events in this cluster that occurred over a vast range of distances and times,” said co-author Grant Tremblay, from the Harvard & Smithsonian Center for Astrophysics CfA). “It began with the black hole a tiny fraction of a light-year across forming a cavity almost 500,000 light-years wide. This single event set in motion the formation of the young star clusters nearly 200 million years later, each a few thousand light-years across.”

The conditions for life throughout the Universe are so plentiful that it seems reasonable to presume there must be extra-terrestrial civilizations in the galaxy. But if that’s true, where are they? The Search for Extra-terrestrial Intelligence (SETI) program and others have long sought to find signals from these civilizations, but so far there has been nothing conclusive. Part of the challenge is that we don’t know what the nature of an alien signal might be. It’s a bit like finding a needle in a haystack when you don’t know what the needle looks like. Fortunately, any alien civilization would still be bound by the same physical laws we are, and we can use that to consider what might be possible. One way to better our odds of finding something would be to focus not on a direct signal from a single world, but the broader echos of an interstellar network of signals.

As noted in a 2022 paper on the arXiv, one physical constraint is that there is a great deal of dust and interstellar gas in the Milky Way. Since radio light penetrates gas and dust better than visible light, the signals sent between stars are likely to be microwave radio signals. Another fact is that if you are traveling between the stars you need to know where you are and where you are going. One way to do this is to use pulsars as navigational beacons. In the paper the author argues that these can be combined as a broadband radio signal from the hub of the alien civilization that contains x-ray pulsar navigation metadata (XNAV).

One of the biggest challenges of detecting stray alien signals is that they would likely be difficult to distinguish from random noise. Even simple signals such as television broadcasts rely upon a known protocol. Without that protocol, we can’t decipher the message. This is similar to the challenge of breaking the Enigma code during World War II. One of the breakthroughs came when it was realized that most messages contained a weather report, so the message likely contained the German word for weather. Metadata in an alien signal could serve a similar role. If we know radio signals should contain XNAV metadata, then we can use this as a starting point. In game theory this is known as a Shelling Point.

The author outlines nine steps for how an interstellar civilization might construct a pulsar navigation system, and what the pattern of that network might be. By creating multiple scenarios, we might be able to recognize certain patterns as technosignatures. As the author notes, one limitation of this approach is that any metadata scenario we imagine is still based on how homo sapiens think, which might not be how an alien intelligence sees things.

All of this is speculative, but it’s worth considering. We will only recognize an alien signal if we better understand the forms they might take, and perhaps a few wild ideas like this one are exactly what we need.

Space debris is a thing.. It seems whether we explore the Earth or space we leave rubbish in our wake. Thankfully, organisations like Astroscale are trying to combat the problem of debris in space with a new commercial debris inspection demonstration satellite. Named ADRAS-J, the satellite – which is now in orbit – is hunting down an old Japanese upper stage rocket body which was launched in 2009.  It will approach to within 30 metres to study the module from every angle and work out how it can be safely de-orbited by a future mission. 

Space debris, or space junk comprises of man made objects orbiting Earth that are no longer needed.  It’s been about 70 years since the launch of Sputnik, the first human made satellite and already, debris in space is a problem and it can be anything from  spent rocket stages to defunct satellites or even fragments that are the results of collisions. Collectively these objects pose a real threat to operational spacecraft due their high speed. Left unchecked, space debris will become a major problem and could even, ultimately, cut off our access to space. 

The ADRAS-J mission marks the world’s first attempt to safely approach and survey a piece of space debris through the Rendezvous and Proximity Operations (RPO) technique. Designed to approach a Japanese upper stage rocket body, ADRAS-J aims to showcase the technique while capturing images to assess the object’s movement and condition.

ADRAS-J was successfully launched from New Zealand on February 18 and is part of Phase 1 of the Japan Aerospace Exploration Agency’s plan to deal with space debris. Its name gives recognition to that purpose ‘Active Debris Removal by Astroscale-Japan’. Its initial target, the Japanese H2A upper stage rocket body. 

The target object lacks any GPS data making it more tricky for the team to rendezvous but perhaps makes it a more realistic target for testing debris analysis activity. Over the next few weeks, the ADRAS-J team will continue to undertake in-orbit tests and checks before it finally, cautiously approaches the object. They will resort to using ground based observational data to approximate its position to make the approach as safe as possible. The initial approach will then be followed up with closer approachers to fully assess the object. 

For over a century, people have dreamed of the day when humanity (as a species) would venture into space. In recent decades, that dream has moved much closer to realization, thanks to the rise of the commercial space industry (NewSpace), renewed interest in space exploration, and long-term plans to establish habitats in Low Earth Orbit (LEO), on the lunar surface, and Mars. Based on the progression, it is clear that going to space exploration will not be reserved for astronauts and government space agencies for much longer.

But before the “Great Migration” can begin, there are a lot of questions that need to be addressed. Namely, how will prolonged exposure to microgravity and space radiation affect human health? These include the well-studied aspects of muscle and bone density loss and how time in space can impact our organ function and cardiovascular and psychological health. In a recent study, an international team of scientists considered an often-overlooked aspect of human health: our microbiome. In short, how will time in space affect our gut bacteria, which is crucial to our well-being?

The team consisted of biomedical researchers from the Ionizing and Non-ionizing Radiation Protection Research Center (INIRPRC) at the Shiraz University of Medical Sciences (SUMS), the Lebanese International University, the International University of Beirut, the MVLS College at The University of Glasgow, the Center for Applied Mathematics and Bioinformatics (CAMB) at Gulf University in Kuwait, the Nuclear Physics Institute (NPI) of the Czech Academy of Sciences (CAS), and the Technische Universität Wien Atominstitut in Vienna. The paper that describes their findings recently appeared in Frontiers of Microbiology.

Artist’s impression of the Space Launch System (SLS) taking off. Credit: NASA

A microbiome is the collection of all microbes that live on and within our bodies, including bacteria, fungi, viruses, and their respective genes. These microbes are key to how our body interacts with the surrounding environment since they can affect how we respond to the presence of foreign bodies and substances. In particular, some microbes alter foreign bodies in ways that make them more harmful, while others act as a buffer that mitigates the effects of toxins. As they note in their study, the microbiota of astronauts will encounter elevated stress from microgravity and space radiation, including Galactic Cosmic Rays (GCR).

Cosmologists are wrestling with an interesting question: how much clumpiness does the Universe have? There are competing but not compatible measurements of cosmic clumpiness and that introduces a “tension” between the differing measurements. It involves the amount and distribution of matter in the Universe. However, dark energy and neutrinos are also in the mix. Now, results from a recent large X-ray survey of galaxy clusters may help “ease the tension”.

The eROSITA X-ray instrument orbiting beyond Earth performed an extensive sky survey of galaxy clusters to measure matter distribution (clumpiness) in the Universe. Scientists at the Max Planck Institute for Extraterrestrial Physics recently shared their analysis of its cosmologically important data.

“eROSITA has now brought cluster evolution measurement as a tool for precision cosmology to the next level,” said Dr. Esra Bulbul (MPE), the lead scientist for eROSITA’s clusters and cosmology team. “The cosmological parameters that we measure from galaxy clusters are consistent with state-of-the-art cosmic microwave background, showing that the same cosmological model holds from soon after the Big Bang to today.”

To get a better feel for what this means, let’s look at what the team is trying to confirm. The idea is to figure out just what the Universe has been like through time. That means understanding matter, its distribution (or clumpiness), and what role dark matter and dark energy have played. It all began just after the Big Bang when the Universe was in a hot, dense state. The only things existing were photons and particles. The Universe expanded and began to condense into regions of higher density. Think of these as density variations, or areas of more or less clumpiness in the primordial soup. As things cooled and expanded, the denser clumps in the soup became galaxies and eventually galaxy clusters. The clumpiness was smoother (or “isotropic”) than expected. That raises questions about the role of dark matter and dark energy, among other things.

eROSITA’s observations of galaxy clusters and distribution of matter showed several interesting results. First, both dark matter and visible matter (baryonic matter), make up about 29 percent of the total energy density of the Universe. Presumably, the rest consists of dark energy, which we don’t know much about, yet. Energy density is the amount of energy stored in a region of space as a function of volume. In cosmology, it also includes any mass in that volume of space.

Astronomers say there’s a wave rippling through our galactic neighborhood that’s playing a part in the birth and death of stars — and perhaps in Earth’s history as well.

The cosmic ripple, known as the Radcliffe Wave, was identified in astronomical data four years ago — but in a follow-up study published today by the journal Nature, a research team lays out fresh evidence that the wave is actually waving, like the wave that fans in a sports stadium create by taking turns standing up and sitting down.

“Similar to how fans in a stadium are being pulled back to their seats by the Earth’s gravity, the Radcliffe Wave oscillates due to the gravity of the Milky Way,” study lead author Ralf Konietzka, a researcher at Harvard and the Harvard-Smithsonian Center for Astrophysics, or CfA, said in a news release. 

The wave — which is named in honor of Harvard Radcliffe Institute, where the undulation was discovered — consists of a string of star clusters spread out over a stretch of the Milky Way measuring about 9,000 light-years in length.

Astronomers reported in 2020 that they identified the wavy pattern by correlating the 3-D locations of the clusters in data from the European Space Agency’s Gaia space telescope, plus observations of dust and gas clouds in the same region.

The gigantic galaxies we see in the Universe today, including our own Milky Way galaxy, started out far smaller. Mergers throughout the Universe’s 13.7 billion years gradually assembled today’s massive galaxies. But they may have begun as mere star clusters.

In an effort to understand the earliest galaxies, the JWST has examined their ancient light for clues as to how they became so massive.

The JWST can effectively see back in time to when the Universe was only about 5% as old as it is now. In that distant past, structures that would eventually become as massive as the Milky Way, and even larger, were only about 1/10,000th as massive as they are now. What clues can the powerful infrared space telescope uncover that show us how galaxies grew so large?

A new paper presents JWST observations of a galaxy at redshift z~8.3. At that redshift, the light has been travelling for over 13 billion years and began its journey only 600 million years after the Big Bang. The galaxy, called the Firefly Sparkle, contains a network of massive star clusters that are evidence of how galaxies grow.

The paper is “The Firefly Sparkle: The Earliest Stages of the Assembly of A Milky Way-type Galaxy in a 600 Myr Old Universe.” The lead author is Lamiya Mowla, an observational astronomer and assistant professor of Physics and Astronomy at Wellesley College. The paper is in pre-print and hasn’t yet been peer-reviewed.

It’s an exciting time in astronomy today, where records are being broken and reset regularly. We are barely two months into 2023, and already new records have been set for the farthest black hole yet observed, the brightest supernova, and the highest-energy gamma rays from our Sun. Most recently, an international team of astronomers using the ESO’s Very Large Telescope in Chile reportedly saw the brightest object ever observed in the Universe: a quasar (J0529-4351) located about 12 billion light years away that has the fastest-growing supermassive black hole (SMBH) at its center.

The international team responsible for the discovery consisted of astrophysicists from the Research School of Astronomy and Astrophysics (RSAA) and the Center for Gravitational Astrophysics (CGA) at the Australian National University (ANU). They were joined by researchers from the University of Melbourne, the Paris Institute of Astrophysics (IAP), and the European Southern Observatory (ESO). The paper that describes their findings, titled “The accretion of a solar mass per day by a 17-billion solar mass black hole,” recently appeared online and will published in the journal Nature Astronomy.

First observed in 1963 by Dutch-American astronomer Maarten Schmidt, quasars (short for “quasi-stellar objects”) are the bright cores of galaxies powered by SMBHs. These black holes collect matter from their surroundings and accelerate it to near the speed of light, which releases tremendous amounts of energy across the electromagnetic spectrum. Quasars become so bright that their cores will outshine all the stars in their disk, making them the brightest objects in the sky and visible from billions of light-years away.

As a general rule, astronomers gauge the growth rate of SMBHs based on the luminosity of their galaxy’s core region – the brighter the quasar, the faster the black hole is accreting matter. In this case, the SMBH at the core of J0529-4351 is growing by the equivalent of one Solar mass a day, making it the fastest-growing black hole yet observed. In the process, the accretion disk alone releases a radiative energy of 2 × 1041 Watts, more than 500 trillion times the luminous energy emitted by the Sun. Christian Wolf, an ANU astronomer and lead author of the study, characterized the discovery in a recent ESO press release:

“We have discovered the fastest-growing black hole known to date. It has a mass of 17 billion Suns, and eats just over a Sun per day. This makes it the most luminous object in the known Universe. Personally, I simply like the chase. For a few minutes a day, I get to feel like a child again, playing treasure hunt, and now I bring everything to the table that I have learned since.”

Japan successfully tested its new flagship H3 rocket after an earlier version failed last year. The rocket lifted off from the Tanegashima Space Center on Saturday, February 17, reaching an orbital altitude of about 670 kilometers (420 miles). It deployed a set of micro-satellites and a dummy satellite designed to simulate a realistic payload.

With the successful launch of the H3, Japan will begin transitioning away from the previous H-2A rocket which has been in service since 2001 and is set to be retired after two more launches. Several upcoming missions depend on the H3, so this successful test was vital.

The launch came after two days of delays because of bad weather. The H3 rocket, built by Mitsubishi Heavy Industries, is now set to become the main launch vehicle of Japan’s space program. The rocket’s first flight in March 2023 failed to reach orbit, which resulted in the loss of an Earth imaging satellite.

The successful launch and deployment of the satellites was a relief for JAXA and members of the project. A livestream of the launch and subsequent successful orbit insertion showed those in the JAXA command cheering and hugging each other.

“I now feel a heavy load taken off my shoulders,” said JAXA H3 project manager Masashi Okada, speaking at a press briefing after the launch. “But now is the real start for H3, and we will work to steadily improve it.”

One of the central predictions of general relativity is that in the end, gravity wins. Stars will fuse hydrogen into new elements to fight gravity and can oppose it for a time. Electrons and neutrons exert pressure to counter gravity, but their stability against that constant pull limits the amount of mass a white dwarf or neutron star can have. All of this can be countered by gathering more mass together. Beyond about 3 solar masses, give or take, gravity will overpower all other forces and collapse the mass into a black hole.

While black holes have a great deal of theoretical and observational evidence to prove their existence, the theory of black holes is not without issue. For one, general relativity predicts that the mass compresses to an infinitely dense singularity where the laws of physics break down. This singularity is shrouded by an event horizon, which serves as a point of no return for anything devoured by the black hole. Both of these are problematic, so there has been a long history of trying to find some alternative. Some mechanism that prevents singularities and event horizons from forming.

One alternative is a gravitational vacuum star or gravitational condensate star, commonly called a gravastar. It was first proposed in 2001, and takes advantage of the fact that most of the energy in the universe is not regular matter or even dark matter, but dark energy. Dark energy drives cosmic expansion, so perhaps it could oppose gravitational collapse in high densities.

Illustration of a hypothetical gravastar. Credit: Daniel Jampolski and Luciano Rezzolla, Goethe University Frankfurt

The original gravastar model proposed a kind of Bose-Einstein condensate of dark energy surrounded by a thin shell of regular matter. The internal condensate ensures that the gravastar has no singularity, while the dense shell of matter ensures that the gravastar appears similar to a black hole from the outside. Interesting idea, but there are two central problems. One is that the shell is unstable, particularly if the gravastar is rotating. There are ways to tweak things just so to make it stable, but such ideal conditions aren’t likely to occur in nature. The second problem is that gravitational wave observations of large body mergers confirm the standard black hole model. But a new gravastar model might solve some of those problems.

One of the largest reentries in recent years, ESA’s ERS-2 satellite is coming down this week.

After almost three decades in orbit, an early Earth-observation satellite is finally coming down this week. The European Space Agency’s (ESA) European Remote Sensing satellite ERS-2 is set to reenter the Earth’s atmosphere on or around Wednesday, February 21st.

Launched atop an Ariane-4 rocket from the Kourou Space Center in French Guiana on April 21st, 1995, ERS-2 was one of ESA’s first Earth observation satellites. ERS-2 monitored land masses, oceans, rivers, vegetation and the polar regions of the Earth using visible light and ultraviolet sensors. The mission was on hand for several natural disasters, including the flood of the Elbe River across Germany in 2006. ERS-2 ceased operations in September 2011.

ERS-2 was placed in a retrograde, Sun-synchronous low Earth orbit, inclined 98.5 degrees relative to the equator. This orbit is typical for Earth-observing and clandestine spy satellites, as it allows the mission to image key target sites at the same relative Sun angle, an attribute handy for image interpretation.

Reentry predictions for the satellite are centered on February 21st at 00:19 Universal Time (UT)+/- 25 hours. As we get closer, expect that time to get refined. The mass of ERS-2 at launch (including fuel) was 2,516 kilograms. Expect most of the satellite to burn up on reentry.

The solar cycle has been reasonably well understood since 1843 when Samuel Schwabe spent 17 years observing the variation of sunspots. Since then, we have regularly observed the ebb and flow of the sunspots cycle every 11 years. More recently ESA’s Solar Orbiter has taken regular images of the Sun to track the progress as we head towards the peak of the current solar cycle. Two recently released images from February 2021 and October 2023 show how things are really picking up as we head toward solar maximum.

The Sun is a great big ball of plasma, electrically charged gas, which has the amazing property that it can move a magnetic field that may be embedded within.  As the Sun rotates, the magnetic field gets dragged around with it but, because the Sun rotates faster at the equator than at the poles, the field lines get wound up tighter and tighter.

Under this immense stressing, the field lines occasionally break, snap or burst through the surface of the Sun and when they do, we see a sunspot. These dark patches on the visible surface of the Sun are regions where denser concentrations of solar material prohibit heat flow to the visible surface giving rise to slightly cooler, and therefore darker patches on the Sun. 

The slow rotation of the Sun and the slow but continuous winding up of the field lines means that sun spots become more and more numerous as the field gets more distorted. Observed over a period of years the spots seem to slowly migrate from the polar regions to the equatorial regions as the solar cycle progresses. 

To try and help understand this complex cycle and unlock other mysteries of the Sun, the European Space Agency launched its Solar Orbiter on 10 February 2020. Its mission to explore the Sun’s polar regions, understand what drives the 11 year solar cycle and what drives the heating of the corona, the outer layers of the Sun’s atmosphere. 

Quasars are fascinating objects; supermassive black holes that are actively feasting on material from their accretion disks. The result is a jet that can outshine the combined light from the entire galaxy! There are smaller blackholes too that are the result of the death of stars and these also sometimes seem to host accretion disks and jets just like their larger cousins. We call these microquasars and, whilst there are similarities between them, there are differences too.

The term quasar gives a clue to their nature, the term is an abbreviated version of ‘qausi-stellar radio source’ which is exactly what they are.  A source of radio energy which seems to present as the pinpoint nature of stars.  The first quasar to be discovered was given the rather unimaginative name ‘3C 273’ and it was found in the constellation Virgo.  Most objects of this nature tend to have catalogue numbers rather than more common names and in the case of 3C 273 it tells us it is the 273rd object in the 3rd Cambridge Catalogue of Radio Sources.

It was in 1964 that we started to understand the nature of quasars and their incredible luminosity which is the result of the accretion of material onto a supermassive black hole. The accretion process seems to drive twin radio lobes that appear as opposing jets out of their rotational axis. The microquasars seem to be scaled-down versions. 

In a paper recently published by J I Katz from the Washington University the differences between the two are explored and, despite the common nature of quasars across the Universe, to date only 19 microquasars have been discovered and there is one key difference emerging.

It seems that the radio lobes are the key.  In quasars, a significant propotion of the power appears to come from particle acceleration along their polar jets, driving the energy release from the radio lobes. In microquasars, this seems to be the opposite with thermal emissions from their accretion disk more prominent. In quasars, for some as yet unknown reason, the accretion of material onto the supermassive black holes seems to drive the particle acceleration along the jet rather than thermal radiation yet this is not the case for the smaller microquasars.