Alexey A. Petrov, University of South Carolina Scientists working with the James Webb Space Telescope discovered three unusual astronomical objects in early 2025, which may be examples of dark stars. The concept of dark stars has existed for some time and could alter scientists’ understanding of how ordinary stars form. However, their name is somewhat misleading. “Dark stars” is one of those unfortunate names that, on the surface, does not accurately describe the objects it represents. Dark stars are not exactly stars, and they are certainly not dark. Still, the name captures the essence of this phenomenon. The “dark” in the name refers not to how bright these objects are, but to the process that makes them shine — driven by a mysterious substance called dark matter. The sheer size of these objects makes it difficult to classify them as stars. As a physicist, I’ve been fascinated by dark matter, and I’ve been trying to find a way to see its traces using particle accelerators. I’m curious whether dark stars could provide an alternative method to find dark matter.

What makes dark matter dark?

Dark matter, which makes up approximately 27% of the universe but cannot be directly observed, is a key idea behind the phenomenon of dark stars. Astrophysicists have studied this mysterious substance for nearly a century, yet we haven’t seen any direct evidence of it besides its gravitational effects. So, what makes dark matter dark?

Humans primarily observe the universe by detecting electromagnetic waves emitted by or reflected off various objects. For instance, the Moon is visible to the naked eye because it reflects sunlight. Atoms on the Moon’s surface absorb photons – the particles of light – sent from the Sun, causing electrons within atoms to move and send some of that light toward us. More advanced telescopes detect electromagnetic waves beyond the visible spectrum, such as ultraviolet, infrared or radio waves. They use the same principle: Electrically charged components of atoms react to these electromagnetic waves. But how can they detect a substance – dark matter – that not only has no electric charge but also has no electrically charged components? Although scientists don’t know the exact nature of dark matter, many models suggest that it is made up of electrically neutral particles – those without an electric charge. This trait makes it impossible to observe dark matter in the same way that we observe ordinary matter. Dark matter is thought to be made of particles that are their own antiparticles. Antiparticles are the “mirror” versions of particles. They have the same mass but opposite electric charge and other properties. When a particle encounters its antiparticle, the two annihilate each other in a burst of energy. If dark matter particles are their own antiparticles, they would annihilate upon colliding with each other, potentially releasing large amounts of energy. Scientists predict that this process plays a key role in the formation of dark stars, as long as the density of dark matter particles inside these stars is sufficiently high. The dark matter density determines how often dark matter particles encounter, and annihilate, each other. If the dark matter density inside dark stars is high, they would annihilate frequently.

What makes a dark star shine?

The concept of dark stars stems from a fundamental yet unresolved question in astrophysics: How do stars form? In the widely accepted view, clouds of primordial hydrogen and helium — the chemical elements formed in the first minutes after the Big Bang, approximately 13.8 billion years ago — collapsed under gravity. They heated up and initiated nuclear fusion, which formed heavier elements from the hydrogen and helium. This process led to the formation of the first generation of stars.

In the standard view of star formation, dark matter is seen as a passive element that merely exerts a gravitational pull on everything around it, including primordial hydrogen and helium. But what if dark matter had a more active role in the process? That’s exactly the question a group of astrophysicists raised in 2008. In the dense environment of the early universe, dark matter particles would collide with, and annihilate, each other, releasing energy in the process. This energy could heat the hydrogen and helium gas, preventing it from further collapse and delaying, or even preventing, the typical ignition of nuclear fusion. The outcome would be a starlike object — but one powered by dark matter heating instead of fusion. Unlike regular stars, these dark stars might live much longer because they would continue to shine as long as they attracted dark matter. This trait would make them distinct from ordinary stars, as their cooler temperature would result in lower emissions of various particles.

Can we observe dark stars?

Several unique characteristics help astronomers identify potential dark stars. First, these objects must be very old. As the universe expands, the frequency of light coming from objects far away from Earth decreases, shifting toward the infrared end of the electromagnetic spectrum, meaning it gets “redshifted.” The oldest objects appear the most redshifted to observers. Since dark stars form from primordial hydrogen and helium, they are expected to contain little to no heavier elements, such as oxygen. They would be very large and cooler on the surface, yet highly luminous because their size — and the surface area emitting light — compensates for their lower surface brightness. They are also expected to be enormous, with radii of about tens of astronomical units — a cosmic distance measurement equal to the average distance between Earth and the Sun. Some supermassive dark stars are theorized to reach masses of roughly 10,000 to 10 million times that of the Sun, depending on how much dark matter and hydrogen or helium gas they can accumulate during their growth. So, have astronomers observed dark stars? Possibly. Data from the James Webb Space Telescope has revealed some very high-redshift objects that seem brighter — and possibly more massive — than what scientists expect of typical early galaxies or stars. These results have led some researchers to propose that dark stars might explain these objects.

In particular, a recent study analyzing James Webb Space Telescope data identified three candidates consistent with supermassive dark star models. Researchers looked at how much helium these objects contained to identify them. Since it is dark matter annihilation that heats up those dark stars, rather than nuclear fusion turning helium into heavier elements, dark stars should have more helium. The researchers highlight that one of these objects indeed exhibited a potential “smoking gun” helium absorption signature: a far higher helium abundance than one would expect in typical early galaxies.

Dark stars may explain early black holes

What happens when a dark star runs out of dark matter? It depends on the size of the dark star. For the lightest dark stars, the depletion of dark matter would mean gravity compresses the remaining hydrogen, igniting nuclear fusion. In this case, the dark star would eventually become an ordinary star, so some stars may have begun as dark stars. Supermassive dark stars are even more intriguing. At the end of their lifespan, a dead supermassive dark star would collapse directly into a black hole. This black hole could start the formation of a supermassive black hole, like the kind astronomers observe at the centers of galaxies, including our own Milky Way. Dark stars might also explain how supermassive black holes formed in the early universe. They could shed light on some unique black holes observed by astronomers. For example, a black hole in the galaxy UHZ-1 has a mass approaching 10 million solar masses, and is very old – it formed just 500 million years after the Big Bang. Traditional models struggle to explain how such massive black holes could form so quickly. The idea of dark stars is not universally accepted. These dark star candidates might still turn out just to be unusual galaxies. Some astrophysicists argue that matter accretion — a process in which massive objects pull in surrounding matter — alone can produce massive stars, and that studies using observations from the James Webb telescope cannot distinguish between massive ordinary stars and less dense, cooler dark stars. Researchers emphasize that they will need more observational data and theoretical advancements to solve this mystery. Alexey A. Petrov, Professor of physics and astronomy, University of South Carolina This article is republished from The Conversation under a Creative Commons license. Read the original article.

NASA goes on an ESCAPADE – twin small, low-cost orbiters will examine Mars’ atmosphere

Christopher Carr, Georgia Institute of Technology and Glenn Lightsey, Georgia Institute of Technology Envision a time when hundreds of spacecraft are exploring the solar system and beyond. That’s the future that NASA’s ESCAPADE, or Escape and Plasma Acceleration and Dynamics Explorers, mission will help unleash: one where small, low-cost spacecraft enable researchers to learn rapidly, iterate, and advance technology and science. The ESCAPADE mission launched on Nov. 13, 2025 on a Blue Origin New Glenn rocket, sending two small orbiters to Mars to study its atmosphere. As aerospace engineers, we’re excited about this mission because not only will it do great science while advancing the deep space capabilities of small spacecraft, but it also will travel to the red planet on an innovative new trajectory. The ESCAPADE mission is actually two spacecraft instead of one. Two identical spacecraft will take simultaneous measurements, resulting in better science. These spacecraft are smaller than those used in the past, each about the size of a copy machine, partly enabled by an ongoing miniaturization trend in the space industry. Doing more with less is very important for space exploration, because it typically takes most of the mass of a spacecraft simply to transport it where you want it to go.

Having two spacecraft also acts as an insurance policy in case one of them doesn’t work as planned. Even if one completely fails, researchers can still do science with a single working spacecraft. This redundancy enables each spacecraft to be built more affordably than in the past, because the copies allow for more acceptance of risk.

Studying Mars’ history

Long before the ESCAPADE twin spacecraft Blue and Gold were ready to go to space – billions of years ago, to be more precise – Mars had a much thicker atmosphere than it does now. This atmosphere would have enabled liquids to flow on its surface, creating the channels and gullies that scientists can still observe today. But where did the bulk of this atmosphere go? Its loss turned Mars into the cold and dry world it is today, with a surface air pressure less than 1% of Earth’s. Mars also once had a magnetic field, like Earth’s, that helped to shield its atmosphere. That atmosphere and magnetic field would have been critical to any life that might have existed on early Mars.

ESCAPADE will measure remnants of this magnetic field that have been preserved by ancient rock and study the flow and energy of Mars’ atmosphere and how it interacts with the solar wind, the stream of particles that the sun emits along with light. These measurements will help to reveal where the atmosphere went and how quickly Mars is still losing it today.

Weathering space on a budget

Space is not a friendly place. Most of it is a vacuum – that is, mostly empty, without the gas molecules that create pressure and allow you to breathe or transfer heat. These molecules keep things from getting too hot or too cold. In space, with no pressure, a spacecraft can easily get too hot or too cold, depending on whether it is in sunlight or in shadow. In addition, the Sun and other, farther astronomical objects emit radiation that living things do not experience on Earth. Earth’s magnetic field protects you from the worst of this radiation. So when humans or our robotic representatives leave the Earth, our spacecraft must survive in this extreme environment not present on Earth. ESCAPADE will overcome these challenges with a shoestring budget totaling US$80 million. That is a lot of money, but for a mission to another planet it is inexpensive. It has kept costs low by leveraging commercial technologies for deep space exploration, which is now possible because of prior investments in fundamental research. For example, the GRAIL mission, launched in 2011, previously used two spacecraft, Ebb and Flow, to map the Moon’s gravity fields. ESCAPADE takes this concept to another world, Mars, and costs a fraction as much as GRAIL. Led by Rob Lillis of UC Berkeley’s Space Sciences Laboratory, this collaboration between spacecraft builders Rocket Lab, trajectory specialists Advanced Space LLC and launch provider Blue Origin – all commercial partners funded by NASA – aims to show that deep space exploration is now faster, more agile and more affordable than ever before.

How will ESCAPADE get to Mars?

ESCAPADE will also use a new trajectory to get to Mars. Imagine being an archer in the Olympics. To hit a bull’s-eye, you have to shoot an arrow through a 15-inch – 40-centimeter – circle from a distance of 300 feet, or 90 meters. Now imagine the bull’s-eye represents Mars. To hit it from Earth, you would have to shoot an arrow through the same 15-inch bull’s-eye at a distance of over 13 miles, or 22 kilometers. You would also have to shoot the arrow in a curved path so that it goes around the Sun. Not only that, but Mars won’t be at the bull’s-eye at the time you shoot the arrow. You must shoot for the spot that Mars will be in 10 months from now. This is the problem that the ESCAPADE mission designers faced. What is amazing is that the physical laws and forces of nature are so predictable that this was not even the hardest problem to solve for the ESCAPADE mission. It takes energy to get from one place to another. To go from Earth to Mars, a spacecraft has to carry the energy it needs, in the form of rocket fuel, much like gasoline in a car. As a result, a high percentage of the total launch mass has to be fuel for the trip. When going to Mars orbit from Earth orbit, as much as 80% to 85% of the spacecraft mass has to be propellant, which means not much mass is dedicated to the part of the spacecraft that does all the experiments. This issue makes it important to pack as much capability into the rest of the spacecraft as possible. For ESCAPADE, the propellant is only about 65% of the spacecraft’s mass. ESCAPADE’s route is particularly fuel-efficient. First, Blue and Gold will go to the L2 Lagrange point, one of five places where gravitational forces of the Sun and Earth cancel out. Then, after about a year, during which they will collect data monitoring the Sun, they will fly by the Earth, using its gravitational field to get a boost. This way, they will arrive at Mars in about 10 more months. This new approach has another advantage beyond needing to carry less fuel: Trips from Earth to Mars are typically favorable to save fuel about every 26 months due to the two planets’ relative positions. However, this new trajectory makes the departure time more flexible. Future cargo and human missions could use a similar trajectory to have more frequent and less time-constrained trips to Mars. ESCAPADE is a testament to a new era in spaceflight. For a new generation of scientists and engineers, ESCAPADE is not just a mission – it is a blueprint for a new collaborative era of exploration and discovery. This article was updated on Nov. 13, 2025 to reflect the ESCAPADE launch’s date and success. Christopher Carr, Assistant Professor of Aerospace Engineering, Georgia Institute of Technology and Glenn Lightsey, Professor of Space Systems Technology, Georgia Institute of Technology This article is republished from The Conversation under a Creative Commons license. Read the original article.