MysticStronomy

Discover the wonders of space and unlock the secrets of the universe in my blog, where we explore the intriguing mysteries that lie beyond Earth.🚀

[mysticstronomy]

DO WE LIVE IN A GIANT VOID??

Blog#560

Wednesday, December 24th, 2025

Welcome back,

One of the biggest mysteries in cosmology is the rate at which the universe is expanding. This can be predicted using the standard model of cosmology, also known as Lambda-cold dark matter (ΛCDM). This model is based on detailed observations of the light left over from the Big Bang – the so-called cosmic microwave background (CMB).

The universe’s expansion makes galaxies move away from each other. The further away they are from us, the more quickly they move. The relationship between a galaxy’s speed and distance is governed by “Hubble’s constant”, which is about 43 miles (70 km) per second per Megaparsec (a unit of length in astronomy). This means that a galaxy gains about 50,000 miles per hour for every million light years it is away from us.

But unfortunately for the standard model, this value has recently been disputed, leading to what scientists call the “Hubble tension”. When we measure the expansion rate using nearby galaxies and supernovas (exploding stars), it is 10% larger than when we predict it based on the CMB.

In our new paper, we present one possible explanation: that we live in a giant void in space (an area with below average density). We show that this could inflate local measurements through outflows of matter from the void.

Outflows would arise when denser regions surrounding a void pull it apart – they’d exert a bigger gravitational pull than the lower density matter inside the void.

In this scenario, we would need to be near the centre of a void about a billion light years in radius and with density about 20% below the average for the universe as a whole – so not completely empty.

Such a large and deep void is unexpected in the standard model – and therefore controversial. The CMB gives a snapshot of structure in the infant universe, suggesting that matter today should be rather uniformly spread out. However, directly counting the number of galaxies in different regions does indeed suggest we are in a local void.

Originally published on https://theconversation.com

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(Saturday, December 27th, 2025)

"WHAT ARE COSMIC RAYS??"

[mysticstronomy]

CAN LIGHT TRAVEL WITHOUT AIR??

Blog#559

Wednesday, December 17th, 2025

Welcome back,

When we think about light, many of us imagine the Sun shining through the sky or a lamp glowing in our room. But here’s a fascinating question : Does light actually need air to travel?

The short answer is: No, light does not need air.

Light is very different from sound. Sound waves are mechanical — they travel by vibrating particles of air, water, or solid matter. That’s why if there’s no air (like in outer space), sound cannot travel.

Light, however, is an electromagnetic wave. That means it doesn’t depend on particles of air to move. Instead, it’s made of oscillating electric and magnetic fields that can travel through the vacuum of space.

Think about sunlight: it takes about 8 minutes and 20 seconds for light from the Sun to reach Earth, crossing the vast emptiness of space where there is no air at all. If light needed air, we would live in complete darkness, unable to see stars, galaxies, or even our own Sun.

So, what medium does light need?

In a vacuum (space): Light travels at its fastest speed — about 299,792 km per second (the famous speed of light).

In air or water: Light slows down because it interacts with the particles in these materials. This is why a straw looks “bent” in a glass of water — a phenomenon called refraction.Light does not need air to travel. It can move freely through the vacuum of space. That’s the reason our universe is visible to us at all!

COMING UP!!

(Saturday, December 20th, 2025)

"DO WE LIVE IN A GIANT VOID??"

[mysticstronomy]

WHY IS PLUTO CALLED A DWARF PLANET??

Blog#558

Wednesday, December 17th, 2025

Welcome back,

Many of us remember being taught at school that Pluto was the 9th planet of the Solar System. So what changed?

In a nutshell, Pluto is considered to not be a planet because of its size, its shape, its orbit and the discovery of many other bodies just like it.

But let's take a look more closely at the history of Pluto, is re-classification as a dwarf planet and how this whole debate got started.

Pluto's status was re-classified from 'planet' to 'dwarf planet' on 24 August 2006 by the International Astronomical Union following a vote of its members.

The official act that took planetary classification from Pluto was IAU Resolution 5A, ‘Definition of a Planet in the Solar System’.

But why was Pluto re-classified, what led to the vote ever taking place, and is Pluto indeed a planet?.

Pluto's journey from its discovery as the 9th planet in our Solar System to its reclassification as a dwarf planet and Kuiper Belt Object is a fascinating tale.

What started off as a curious orbital anomaly in the 18th century turned into the discovery of an object that forced us to rethink our ideas of what a planet should be, and ultimately how our Solar System began.

Let's take a look back at how Pluto was first discovered.

Originally published on https://www.skyatnightmagazine.com

COMING UP!!

(Saturday, December 20th, 2025)

"CAN LIGHT TRAVEL WITHOUT AIR??"

[mysticstronomy]

HOW DO GALAXIES DIE??

Blog#557

Saturday, December 13th, 2025

Welcome back,

Most of what astronomers know about the universe comes from what they can see. So their ideas have been prejudiced toward stars and galaxies, which are bright. But most of the regular matter in the universe is in the form of gas, which is dim. Gas called the intergalactic medium fills the space between galaxies; the gas of the circumgalactic medium surrounds galaxies more closely. The gas in both places regulates the birth, life and death of the galaxies, and holds a detailed history of the universe. Only lately have astronomers been able to detect it.

Shortly after its birth, the universe was filled with gas, mostly hydrogen. Over time, here and there, gravity pulled the gas into clouds which turned into galaxies and in which stars ignited. Stars shine by thermonuclear burning of the gas; of those that die in explosions, some blow the gas back out of the galaxies. Out in intergalactic space, the gas cools and gets denser, until gravity pulls it back into the galaxy where new stars form. The process repeats: Gravity condenses gas into galaxies and stars, stars blow up and kick the gas out, gravity cycles the gas back in and makes new stars.

In time, any given galaxy begins to run out of recyclable gas. Without gas, it can’t form new stars; the old stars live out their lives and die, and eventually the galaxy dies too. Galaxies sit in a bath of gas, the medium from which they were born and which fuels them. The galaxies breathe gas in and out, and their stars burn until their gas is gone.

This is theory. The problem with verifying it has been that astronomers’ instruments could barely detect signs of gas, let alone map its comings and goings. With more sensitive instruments and dogged surveys, astronomers now know more. Convincing evidence suggests that the intergalactic medium is rich in gas, which fills the universe and seeds galaxies.

Less-convincing and sometimes puzzling evidence in the circumgalactic medium shows that galaxies live by recycling gas into and out of stars. And astronomers have only preliminary evidence supporting arguments for how galaxies might run out of gas, stop forming stars and die.

Galaxies shine, gas barely glows. Gas becomes visible when it sits in front of something bright — most notably quasars, the cores of extremely distant and extraordinarily brilliant galaxies — and absorbs its light. To astronomers analyzing the light that reaches Earth, the gas shows up as dark lines in the spectra of the quasars’ light. The pattern of the dark absorption lines held a surprising amount of information, including the distance (and so the age) of the gas: It was visible at distances vastly greater, and therefore at times vastly earlier, than normal galaxies then were.

Because spectra also reveal the gas’s chemical components, density, temperature, and motion toward or away from Earth, for the last 50 years quasar absorption line studies have remained one of the best ways to study

What is not a scenario but shown by hard evidence is that at some point, a galaxy runs out of fuel and dies — a process called “quenching.” Astronomers have known for nearly two decades, when the Sloan Digital Sky Survey classified galaxies into two general categories, that galaxies with lots of gas and actively forming stars are blue, and those with little gas and dying stars are red. Most galaxies are either blue or red, with almost nothing in between.

If galaxies are either living or dying, and if they die by running out of gas to make new stars, it means that however galaxies die, they run out of gas fast. How that happens remains unclear. Finding evidence for recycling has proved difficult, and finding evidence for a quenching mechanism is so far impossible.

The circumgalactic medium should hold that evidence, but in fact observations have only made the problem more intractable.

So far, what observers have found doesn’t add up to a coherent story of how galaxies are born, live and die. Stories are theory’s job, and in astronomy, theory often comes in the form of computer simulations. Theorists put together gravity, hydrodynamics, regular matter that shines and dark matter that doesn’t, and let the simulation re-create the evolution of galaxies. Then they compare the simulated galaxies with real ones: shape, rates of star formation, assumed method of quenching, rates of outflows, evidence of infalls, temperatures, density and metallicity. At present, the simulations run on two scales, the large intergalactic and smaller circumgalactic; no one simulation can cover both.

Originally published on https://www.astronomy.com

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(Saturday, December 17th, 2025)

"WHY IS PLUTO CALLED A DWARF PLANET??"

[mysticstronomy]

DO BLACK HOLES REALLY NEED SINGULARITIES??

Blog#556

Wednesday, November 12th, 2025

Welcome back,

Whenever someone talks about black holes, they almost always talk about the event horizon and the singularity. After all, that's what defines a black hole, right? Well, it depends on what you mean by black hole. There are some who would argue a black hole doesn't need a singularity, and that could mean they don't even have an event horizon.

Before we dive into black holes, let's first distinguish between the two types. On the one hand, we have theoretical black holes as described in general relativity. These are solutions to Einstein's GR field equations known as metrics. The first black hole metric was discovered by Karl Schwarzschild and describes a simple, non-rotating black hole.

Other metrics have been found over the years, such as the Kerr metric discovered in 1963 by Roy Kerr, which describes an uncharged rotating black hole. This is the metric used to visualize all those cool scenes in movies such as "Interstellar."

On the other hand, there are the black holes we have directly observed, such as M87* and the black hole at the center of our galaxy, SagA*. The Event Horizon Telescope has gathered a great deal of data on these two black holes, and from this we know they rotate and have a near-horizon structure that—to the limits of our observation—agrees perfectly with the Kerr model.

Of course, none of our observations can see inside a black hole, so we don't know for sure if it has a singularity. Likewise, we can't see the event horizon itself, since any light crossing the event horizon is trapped forever. So while we have no evidence to suggest black holes don't have singularities and event horizons, alternative models that agree with current observations are also theoretically possible.

The reason this matters is that while singularities and event horizons naturally appear in the black hole metrics, they also cause all manner of problems. A simple singularity is a mathematical point of infinite density and zero volume where the laws of physics break down.

It's so problematic that physicists have invoked the cosmic censorship hypothesis to claim that singularities are always shrouded by an event horizon so we don't have to worry about them.

But event horizons have their own problems. Since any object crossing an event horizon can never escape the black hole, the information contained within the object is forever lost to the universe, creating an information paradox. Round and round we go.

One way to resolve all this is to find a black hole model without a singularity and event horizon. After all, general relativity is a classical theory like Newtonian dynamics. The real universe is quantum in nature, so we really should have a quantum theory of gravity.

And there's some evidence that quantum physics could solve these issues. Heisenberg's uncertainty principle states that you can't have an exact mass at an exact point, so quantum theory likely prevents singularities from forming, and Hawking radiation could allow energy and information to escape a black hole in time.

Most of the theoretical explorations of these ideas focus on the quantum side of things. For example, in loop quantum gravity, the quantum foam of spacetime could mean that black holes form a "Planck star" within the event horizon rather than a singularity. A similar model known as the fuzzball appears in string theory, where the singularity is replaced by a ball of degenerate strings. There are also alternative classical theories to general relativity that can eliminate the problems of GR.

Originally published on https://phys.org.

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(Saturday, November 15th, 2025)

"WHY IS OUR GALAXY DYING??"

[mysticstronomy]

WHY DOES THE SPEED OF LIGHT HAS A SPEED LIMIT??

Blog#555

Saturday, November 8th, 2025

Welcome back,

The speed of light in vacuum is the universal speed limit, meaning that nothing can ever travel faster than this speed. If the speed of light is a universal and fundamental limit, you may wonder why it has a seemingly random value of 299,792,458 meters per second. Why not 2 m/s more? or 5 m/s less? or a nice round number? What magical thing happens right at that speed?

The first thing to note is that the speed of light in vacuum only has the value of exactly 299,792,458 if you are using meters to measure lengths and seconds to measure time (using the post-1983 definition of the meter). If you instead use miles to measure lengths and hours to measure time, the speed of light in vacuum is approximately 670,616,629 mph. If you instead use miles per second, it is approximately 186,282 mi/s.

As should be obvious at this point, the actual number that describes the speed of light depends on which units you use. There is nothing special about these numbers themselves. These numbers have scientific meaning and can be useful, but only insofar as you have defined a unit system and measured things using that unit system. You can, in principle, define your unit system however you want and get the correct value for the speed of light to be whatever number you want (as long as it's greater than zero). For instance, if I define an "opti-oddimeter" as a distance that is exactly equivalent to 23,060,958 4/13 meters, then the correct value for the speed of light is exactly 13 opti-oddimeters per second, which might make some people uneasy!

The seemingly random nature of the numeric value of the speed of light is an artifact of choosing a non-ideal unit system. Meters, miles, seconds, and hours were defined long before much was known about the speed of light. The original definitions of these units have nothing to do with light, so it should be no surprise that the value for the speed of light using such units is such a seemingly random number.

Can we define a different unit system that is more relevant to the basic physical nature of light and therefore end up with a number for the speed of light that makes more sense? Yes. In fact, this has already been done by physicists. The unit system called the natural units of particle physics has its units defined such that the numeric value for the speed of light is exactly 1.

As you can see, this choice of units leads to a much more natural value for the speed of light in vacuum. The speed of light having a value of exactly 1 makes sense because no proper fraction is greater than 1, just like no speed can be greater than the speed of light. The number 1 is the same as 100%, and 100% often means the largest amount possible. Therefore the value of a speed in natural units gives you an immediate sense of how close that speed is to the highest possible speed. For instance, an object that has a speed of 0.20 in natural units has a speed that is 20% of the speed of light in vacuum, which is the maximum possible speed in the universe. In summary, the seemingly random value of the speed of light in vacuum is an artifact of using a non-ideal unit system. This randomness goes away when you use natural units.

Originally published on https://www.wtamu.edu

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(Wednesday, November 12th, 2025)

"DO BLACK HOLES REALLY NEED SINGULARITIES??"

[mysticstronomy]

WHERE DOES THE EXPANDING UNIVERSE BEGIN??

Blog#554

Wednesday, November 5th, 2025

Welcome back,

Some 13.8 billion years ago, the universe began with a rapid expansion we call the big bang. After this initial expansion, which lasted a fraction of a second, gravity started to slow the universe down. But the cosmos wouldn’t stay this way. Nine billion years after the universe began, its expansion started to speed up, driven by an unknown force that scientists have named dark energy.

But what exactly is dark energy?

The short answer is: We don't know. But we do know that it exists, it’s making the universe expand at an accelerating rate, and approximately 68.3 to 70% of the universe is dark energy.

It All Started With Cepheids

Dark energy wasn't discovered until the late 1990s. But its origin in scientific study stretches all the way back to 1912 when American astronomer Henrietta Swan Leavitt made an important discovery using Cepheid variables, a class of stars whose brightness fluctuates with a regularity that depends on the star's brightness.

All Cepheid stars with a certain period (a Cepheid’s period is the time it takes to go from bright, to dim, and bright again) have the same absolute magnitude, or luminosity – the amount of light they put out. Leavitt measured these stars and proved that there is a relationship between their regular period of brightness and luminosity. Leavitt’s findings made it possible for astronomers to use a star’s period and luminosity to measure the distances between us and Cepheid stars in far-off galaxies (and our own Milky Way).

Around this same time in history, astronomer Vesto Slipher observed spiral galaxies using his telescope’s spectrograph, a device that splits light into the colors that make it up, much like the way a prism splits light into a rainbow.

He used the spectrograph, a relatively recent invention at the time, to see the different wavelengths of light coming from the galaxies in different spectral lines. With his observations, Silpher was the first astronomer to observe how quickly the galaxy was moving away from us, called redshift, in distant galaxies. These observations would prove to be critical for many future scientific breakthroughs, including the discovery of dark energy.

Redshift is a term used when astronomical objects are moving away from us and the light coming from those objects stretches out.

Light behaves like a wave, and red light has the longest wavelength. So, the light coming from objects moving away from us has a longer wavelength, stretching to the “red end” of the electromagnetic.

Discovering an Expanding Universe

The discovery of galactic redshift, the period-luminosity relation of Cepheid variables, and a newfound ability to gauge a star or galaxy’s distance eventually played a role in astronomers observing that galaxies were getting farther away from us over time, which showed how the universe was expanding. In the years that followed, different scientists around the world started to put the pieces of an expanding universe together.

In 1922, Russian scientist and mathematician Alexander Friedmann published a paper detailing multiple possibilities for the history of the universe. The paper, which was based on Albert Einstein’s theory of general relativity published in 1917, included the possibility that the universe is expanding.

In 1927, Belgian astronomer Georges Lemaître, who is said to have been unaware of Friedmann’s work, published a paper also factoring in Einstein’s theory of general relativity. And, while Einstein stated in his theory that the universe was static, Lemaître showed how the equations in Einstein’s theory actually support the idea that the universe is not static but, in fact, is actually expanding.

Originally published on https://science.nasa.gov

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(Saturday, November 8th, 2025)

"WHY DOES THE SPEED OF LIGHT HAS A SPEED LIMIT??"

[mysticstronomy]

WHY IS 95% OF THE UNIVERSE INVISIBLE??

Blog#553

Saturday, November 1st, 2025

Welcome back,

For as long as humans have roamed the Earth, we have sought to find our place in the cosmos. From the city-states of ancient Greece to the soaring capstones of the Egyptian pyramids, across the deserts and towering mountains of ancient China down to the rolling plains of Mesoamerica, humans have sought to understand how the universe works. They developed mathematics to trace the motions of the planets, estimated the circumference of the Earth by walking from city to city, created star tables and timekeeping codices, and even recorded celestial events like Halley’s Comet, supernovae, and eclipses.

With time, we have refined our models of the Universe. Using ellipses, Johannes Kepler reconfigured celestial motions. Galileo revolutionized Copernicus’ heliocentric model of the Solar System by discovering that the Sun, not the Earth, is the body around which all other elements of the Solar System orbit. Isaac Newton developed the theory of gravity, which was later supplanted by Albert Einstein’s theory of general relativity.

Discovery by discovery, we paint in the gaps of the picture of our Universe; and yet somehow, with each brushstroke, that image morphs, evolving into something ever-changing, new, and unrecognizable. The Universe that Kepler and Galileo, Copernicus and Kepler, Newton and Galileo, and even Einstein understood is different from the one we know today.

Today’s understanding of the Universe is unsettling. It is not one that fits in a tidy little box with neat lines and a perfect lid. Our Universe is mystifying, complex. It defies expectations.

For starters, our Universe is not a static, enclosed entity. Our Universe is expanding. From everywhere all at once, the fabric of spacetime is stretching away from everywhere else like an inflating balloon, carrying galaxies along with it. Photons traveling the lanes of the cosmos are stretched along with spacetime, their wavelengths growing ever-longer, or redder, thus red-shifting with the expansion of space.

Our Universe isn’t expanding into anything. To our knowledge, there is no extra dimension around the Universe; rather, space itself is expanding, causing the space between galaxy clusters — the largest gravitationally bound objects in the Universe — to get bigger and bigger with time.

And this leads us to the following unsettling conclusion: there’s no center to our Universe. Everywhere is the “center” because everything everywhere is moving away from everything else, all at once.

But the Universe isn’t just expanding.

It’s accelerating.

With each passing moment, an unknown repulsive, persistent force dubbed “dark energy” is stretching the fabric of the Universe. Dark energy is a fundamental property of space itself; invisible, smooth, and constant — and yet we are entirely unsure what it truly is.

And then there is dark matter — the invisible, clumpy matter that binds galaxies together. In many ways, dark matter is the corollary to dark energy: Where dark energy stretches space apart, dark matter knits matter together. They are both invisible — neither interacts with radiation or light — and yet they are ever-present, dark matter acting as the cosmic glue for large-scale structure formation, and dark energy a principal ingredient in the Universe’s evolution.

The afterglow of the Big Bang, known as the cosmic microwave background, is imprinted on the fabric of spacetime, a relic of radiation from when the Universe was extraordinarily hot, dense, and smooth. By mapping its bumps and irregularities and comparing with galaxy surveys, scientists have found that 70% of the Universe is made up of dark energy. Meanwhile, 25% of the Universe is dark matter.

Just 5% of the Universe is ordinary matter.

That’s the ordinary matter of everyday life: your hair and clothes, your atoms and organs, the food you eat and the dogs that kiss you, the air and the sea, the Sun and the Moon. Everything we know — everything we see — is just 5% of everything in the Universe.

Originally published on https://bigthink.com

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(Wednesday, November 5th, 2025)

"WHERE DOES THE EXPANDING UNIVERSE BEGIN??"

[mysticstronomy]

WHAT ARE THE FERMI BUBBLES??

Blog#552

Wednesday, October 29th, 2025

Welcome back,

In 2010, gamma-ray observations by Fermi revealed previously unknown features in our galaxy that stretch halfway across the sky. Now called the Fermi Bubbles, these mysterious structures (magenta in the image above) emerge above and below the center of our galaxy, spanning a total length of about 50,000 light-years.

The plane of our galaxy (shown in blue above) glows brightly in gamma rays, which result when high-energy particles called cosmic rays interact with gas and dust. The Fermi Bubbles emit higher-energy gamma rays than the rest of the galaxy's disk. (In the interactive, clicking on the Gamma-ray Catalog button changes the background to an all-sky view of this so-called diffuse emission.)

The bubbles may be related to the release of vast amounts of energy emitted from the supermassive black hole at the center of our Milky Way galaxy. We know that in other galaxies, supermassive black holes that ingest large amounts of matter can power high-energy jets. It's possible the Milky Way's central black hole went through such a phase in the past, producing jets responsible for the Fermi Bubbles we see today.

A completely unexpected discovery like the Fermi Bubbles is a special treat. However, scientists know that there are many more surprises waiting to be uncovered by Fermi. In the most recent catalog of sources from Fermi's Large Area Telescope, fully a third of detected source positions are not known to have a gamma-ray emitting object at that location. What could be producing these gamma rays?

That's the question many scientists are hoping to answer as Fermi continues its mission.

Originally published on https://fermi.gsfc.nasa.gov

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(Saturday, November 1st, 2025)

"WHY IS 95% OF THE UNIVERSE INVISIBLE??"

[mysticstronomy]

WHAT IS THE PHOENIX CLUSTER??

Blog#551

Saturday, October 25th, 2025

Welcome back,

The core of a massive cluster of galaxies appears to be pumping out far more stars than it should. Now researchers at MIT and elsewhere have discovered a key ingredient within the cluster that explains the core’s prolific starburst.

In a new study published in Nature, the scientists report using NASA’s James Webb Space Telescope (JWST) to observe the Phoenix cluster — a sprawling collection of gravitationally bound galaxies that circle a central massive galaxy some 5.8 billion light years from Earth. The cluster is the largest of its kind that scientists have so far observed. For its size and estimated age, the Phoenix should be what astronomers call “red and dead” — long done with any star formation that is characteristic of younger galaxies.

But astronomers previously discovered that the core of the Phoenix cluster appeared surprisingly bright, and the central galaxy seemed to be churning out stars at an extremely vigorous rate. The observations raised a mystery: How was the Phoenix fueling such rapid star formation?

In younger galaxies, the “fuel” for forging stars is in the form of extremely cold and dense clouds of interstellar gas. For the much older Phoenix cluster, it was unclear whether the central galaxy could undergo the extreme cooling of gas that would be required to explain its stellar production, or whether cold gas migrated in from other, younger galaxies.

Now, the MIT team has gained a much clearer view of the cluster’s core, using JWST’s far-reaching, infrared-measuring capabilities. For the first time, they have been able to map regions within the core where there are pockets of “warm” gas. Astronomers have previously seen hints of both very hot gas, and very cold gas, but nothing in between.

The detection of warm gas confirms that the Phoenix cluster is actively cooling and able to generate a huge amount of stellar fuel on its own.

“For the first time we have a complete picture of the hot-to-warm-to-cold phase in star formation, which has really never been observed in any galaxy,” says study lead author Michael Reefe, a physics graduate student in MIT’s Kavli Institute for Astrophysics and Space Research. “There is a halo of this intermediate gas everywhere that we can see.”

“The question now is, why this system?” adds co-author Michael McDonald, associate professor of physics at MIT. “This huge starburst could be something every cluster goes through at some point, but we’re only seeing it happen currently in one cluster.

The other possibility is that there’s something divergent about this system, and the Phoenix went down a path that other systems don’t go. That would be interesting to explore.”

The Phoenix cluster was first spotted in 2010 by astronomers using the South Pole Telescope in Antarctica. The cluster comprises about 1,000 galaxies and lies in the constellation Phoenix, after which it is named. Two years later, McDonald led an effort to focus in on Phoenix using multiple telescopes, and discovered that the cluster’s central galaxy was extremely bright. The unexpected luminosity was due to a firehose of star formation. He and his colleagues estimated that this central galaxy was turning out stars at a staggering rate of about 1,000 per year.

Originally published on https://news.mit.edu

COMING UP!!

(Wednesday, October 29th, 2025)

"WHAT ARE THE FERMI BUBBLES??"

[mysticstronomy]

WHAT DOES A WHITE HOLE DO??

Blog#550

Wednesday, October 22nd, 2025

Welcome back,

White holes are theoretical cosmic regions that function in the opposite way to black holes. Just as nothing can escape a black hole, nothing can enter a white hole.

White holes were long thought to be a figment of general relativity born from the same equations as their collapsed star brethren, black holes. More recently, however, some theorists have been asking whether these twin vortices of spacetime may be two sides of the same coin.

To a spaceship crew watching from afar, a white hole looks exactly like a black hole. It has mass. It might spin. A ring of dust and gas could gather around the event horizon — the bubble boundary separating the object from the rest of the universe. But if they kept watching, the crew might witness an event impossible for a black hole — a belch. "It's only in the moment when things come out that you can say, 'ah, this is a white hole,'" said Carlo Rovelli, a theoretical physicist at the Centre de Physique Théorique in France.

Physicists describe a white hole as a black hole's "time reversal," a video of a black hole played backwards, much as a bouncing ball is the time-reversal of a falling ball. While a black hole's event horizon is a sphere of no return, a white hole's event horizon is a boundary of no admission — space-time's most exclusive club. No spacecraft will ever reach the region's edge.

Objects inside a white hole can leave and interact with the outside world, but since nothing can get in, the interior is cut off from the universe's past: No outside event will ever affect the inside. "Somehow it's more disturbing to have a singularity in the past that can affect everything in the outside world," said James Bardeen, a black-hole pioneer and professor emeritus at the University of Washington.

Einstein's field equations hit physics like a tsunami in 1915, and theorists are still sorting through the wreckage. Beyond describing the force of gravity, his hypotheses also brought a paradigm-shattering message about the nature of reality. More than a rigid backdrop, space and time bend and fold along with the mass of stars and planets. That insight sparked a race to calculate just how much abuse space could take from the matter that drifts through it.

Within a year, physicist and astronomer Karl Schwarzschild found the first exact solution to Einstein's equations, calculating how space-time curves around a single ball of mass. In his answer lay the seeds of what physicists today call a singularity — a spherical mass shrunken down to an infinitely dense point, wrapping space around it so tightly that the region pinches off from the rest of the universe. It forms a no man's land whose event horizon fractures the link between cause and effect.

Originally published on https://www.space.com

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(Saturday, October 25th, 2025)

"WHAT IS THE PHOENIX CLUSTER??"

[mysticstronomy]

IS THE UNIVERSE INFINITE, OR DOES IT HVAVE A LIMIT??"

Blog#549

Saturday, October 18th, 2025

Welcome back,

After a century of observations spanning the breadth of the cosmos and theoretical insights that push humanity's vision of the universe to its utmost limits, we can finally, confidently say that the universe is infinite.

Or not. It's complicated.

Let's start with something we can say for certain: We live in an expanding universe. But if the universe is expanding, then what is it expanding into? And what is it expanding from? Where's the edge of the universe, and where is its center?

It's easy to imagine an expanding universe, and there are plenty of analogies to help guide our thinking. We can imagine drawing little galaxies on the surface of a balloon and inflating that balloon to see the galaxies getting farther apart. We can imagine baking a loaf of bread with raisins in it and seeing how, as the bread rises, the raisins get farther apart.

But the balloon has both a center and an edge. And the bread has a center and a crust. So where's the center of the universe, and where is its edge?

Here's the uncomfortable answer: The Big Bang has no center, and it has no edge. How can this make any sense?

Let's start with the center. Where did the Big Bang start? Right here. And right over there. And in the next galaxy over. The Big Bang happened everywhere, all at once. It had to happen everywhere, because everywhere is, by definition, part of the universe. It was not an explosion that occurred somewhere in space. It was an explosion of space — when the expansion of the universe first got started. It was not a place but a time.

Now what about the other side of the coin? If the universe is expanding, what is it expanding into? Where's the crust in our expanding loaf of bread, and what's the oven we're sitting in?

This is going to get weird. I don't even want to say something like "the universe isn't expanding into anything," because that still conjures up the wrong mental image. It's too tempting to imagine a wall or boundary, with galaxies and stuff on one side and nothingness on the other, with the universe expanding to fill that nothingness.

But that's wrong. Even the vacuum of space is something. There are still points, locations and existence. There's no "outside" of the universe because "outside" implies existence, even an empty one. But the universe is, by definition, all there is. There is nothing to physical reality except the universe. Walls separate one region from another, but the universe comprises all of the regions simultaneously.

If there were an edge, you could imagine working hard enough to get outside that edge. But that's not possible. There is no outside; there is no side. There is just the universe.

Originally published on https://www.space.com

COMING UP!!

(Wednesday, October 22nd, 2025)

"WHAT DOES A WHITE HOLE DO??"

[mysticstronomy]

WHAT IS THE GREAT ATTRACTOR??

Blog#548

Wednesday, October 15th, 2025

Welcome back,

No matter what you're doing right now – sitting, standing, walking – you're moving.

Specifically, you're moving at least four different ways.

First, Earth is spinning around on its axis at about 1,000 miles per hour right now, or about 1,600 kilometers per hour. This rotation is the reason we have days. Second, Earth and other planets in our solar system are orbiting the sun. Our planet does that at around 67,000 miles per hour, or about 108,000 kilometers per hour.

That's why we have years. And third, you're moving because the sun and the rest of our solar system is orbiting the center of the Milky Way galaxy at over 500,000 miles per hour, or 828,000 kilometers per hour.

On top of all that, you're moving because the entire universe is expanding outward. All the time.

But in the 1970s, astrophysicists noticed that something was off about our galactic neighborhood, or Local Group. The whole clump of neighboring galaxies were being pulled off course at over one million miles per hour, towards something we couldn't see.

They called this region the Great Attractor. But their ability to study it was limited.

"The Milky Way has millions and millions of stars and a lot of dust, which is blocking all that information that we could be measuring in that direction. So our own galaxy's blocking the Great Attractor," says Jorge Moreno, a computational astrophysicist at Pomona College. This area we cannot see is known to researchers as the Zone of Avoidance.

Scientists still don't know the full details of what and exactly how the Milky Way and its neighboring galaxies off course, but there have been several candidates over the last few decades.

Most recently, the prime suspect is the supercluster Laniakea, which is Hawaiian for 'immense heaven' or 'immeasurable heaven.'

Originally published on https://www.npr.org

COMING UP!!

(Saturday, October 18th, 2025)

"IS GHE UNIVERSE INFINITE, OR DOES IT HVAVE A LIMIT??"

[mysticstronomy]

DO ZOMBIE STARS EXIST??

Blog#547

Saturday, October 11th, 2025

Welcome back,

This white dwarf, WD 0525+526, hides carbon traces in its atmosphere that only ultraviolet light could reveal — a telltale sign of its explosive past.

An international group of astronomers has identified a rare stellar object: an ultra-massive white dwarf created when a white dwarf combined with another star, rather than forming from the life cycle of a single star. Using the ultraviolet sensitivity of NASA’s Hubble Space Telescope, the team uncovered this unusual case, hinting that such merger-born white dwarfs may occur more often than scientists once believed.

“It’s a discovery that underlines things may be different from what they appear to us at first glance,” explained Boris Gaensicke of the University of Warwick in the United Kingdom, principal investigator of the Hubble program. “Until now, this appeared as a normal white dwarf, but Hubble’s ultraviolet vision revealed that it had a very different history from what we would have guessed.”

Astronomers using NASA’s Hubble Space Telescope have found a rare ultra-massive white dwarf formed from a stellar merger. The discovery was made possible by Hubble’s sensitive ultraviolet observations and suggests these unusual white dwarfs may be more common than once thought.

A white dwarf is an extremely dense stellar remnant about the size of Earth, marking the final stage for stars that are not large enough to end their lives in core-collapse supernovae. In roughly 5 billion years, our own Sun will follow this path and shrink into a white dwarf.

Although a white dwarf can theoretically reach up to 1.4 times the Sun’s mass, most are less massive. The heavier examples, known as ultra-massive white dwarfs, can arise in two ways: either from the evolution of a single massive star or from the merger of a white dwarf with another star, such as a close binary companion.

Originally published on https://scitechdaily.com

COMING UP!!

(Wednesday, October 15th, 2025)

"WHAT IS THE GREAT ATTRACTOR??"

[mysticstronomy]

WHAT WAS THE EARLY UNIVERSE LIKE??

Blog#546

Wednesday, October 8th, 2025

Welcome back,

The cosmic story that unfolded following the Big Bang is ubiquitous no matter where you are. The formation of atomic nuclei, atoms, stars, galaxies, planets, complex molecules, and eventually life is a part of the shared history of everyone and everything in the Universe. As we understand it today, life on our world began, at the latest, only a few hundred million years after Earth was formed.

That puts life as we know it already nearly 10 billion years after the Big Bang. The Universe couldn’t have formed life from the very first moments; both the conditions and the ingredients were all wrong. But that doesn’t mean it took all those billions and billions of years of cosmic evolution to make life possible. It could have begun when the Universe was just a few percent of its current age. Here’s when life might have first arisen in our Universe.

At the moment of the hot Big Bang, the raw ingredients for life could in no way stably exist. Particles, antiparticles, and radiation all zipped around at relativistic speeds, blasting apart any bound structures that might form by chance. As the Universe aged, though, it also expanded and cooled, reducing the kinetic energy of everything in it. Over time, antimatter annihilated away, stable atomic nuclei formed, and electrons could stably bind to them, forming the first neutral atoms in the Universe.

Yet these earliest atoms were only hydrogen and helium: insufficient for life. Heavier elements, such as carbon, nitrogen, oxygen and more, are required to build the molecules that all life processes rely on. For that, we need to form stars in great abundance, have them go through their life-and-death cycle, and return the products of their nuclear fusion to the interstellar medium.

It takes 50-to-100 million years to form the first stars, sure, which form in relatively large clusters. But in the densest regions of space, these star clusters will gravitationally pull in other matter, including material for additional stars and other star clusters, paving the way for the first galaxies. By time only ~200-to-250 million years have passed, not only will multiple generations of stars have lived-and-died, but the earliest star clusters will have grown into galaxies.

This is important, because we don’t just need to create the heavy elements like carbon, nitrogen, and oxygen; we need to create enough of them — and all of the life-essential elements — to produce a wide diversity of organic molecules.

We need those molecules to stably exist in a location where they can experience an energy gradient, such as on a rocky moon or planet in the vicinity of a star, or with enough undersea hydrothermal activity to support certain chemical reactions.

And we need for those locations to be stable enough that whatever counts as a life process can self-sustain.

Originally published on https://www.forbes.com

COMING UP!!

(Saturday, October 11th, 2025)

"DO ZOMBIE STARS EXIST?? "

[mysticstronomy]

WHY DOES STARS TWINKLE AND PLANETS DO NOT??

Blog#545

Saturday, October 4th, 2025

Welcome back,

Stars twinkle because they’re so far away from Earth that, even through large telescopes, they appear only as pinpoints. And it’s easy for Earth’s atmosphere to disturb the pinpoint light of a star. As a star’s light pierces our atmosphere, it’s refracted – causing it to change direction slightly – by the various temperature and density layers in Earth’s atmosphere. You might think of it as the light traveling a zig-zag path to our eyes, instead of the straight path the light would travel if Earth didn’t have an atmosphere.

Astronomers use the term “scintillation” to describe the twinkling of stars.

Planets shine more steadily because they’re closer to Earth and so appear not as pinpoints, but as tiny disks in our sky. You can see planets as disks if you looked through a telescope, while stars remain pinpoints. Earth’s atmosphere refracts the light from these little disks as it travels toward our eyes.

But – while the light from one edge of a planet’s disk might “zig” one way – light from the opposite edge of the disk might be “zagging” in an opposite way. The zigs and zags of light from a planetary disk cancel each other out, and that’s why planets appear to shine steadily.

You might see planets twinkling if you spot them low in the sky. That’s because, in the direction of any horizon, you’re looking through more atmosphere than when you look overhead.

If you could see stars and planets from outer space, both would shine steadily. There’d be no atmosphere to disturb the steady streaming of their light.

Can you figure out which objects are stars and which are planets just by looking for the twinklers vs the non-twinklers? Experienced observers often can, but, at first, if you can recognize a planet in some other way, you might notice the steadiness of its light by contrasting it to a nearby star.

Originally published on https://earthsky.org

COMING UP!!

(Wednesday, October 8th, 2025)

"WHAT WAS THE EARLY UNIVERSE LIKE??"

[mysticstronomy]

IS OUR SOLAR SYSTEM SURROUNDED BY A VOID??

Blog#544

Wednesday, October 1st, 2025

Welcome back,

The Solar System floats in the middle of a peculiarly empty region of space.

This region of low-density, high-temperature plasma, about 1,000 light-years across, is surrounded by a shell of cooler, denser neutral gas and dust. It's called the Local Bubble, and precisely how and why it came to exist, with the Solar System floating in the middle, has been a challenge to explain.

A team of astronomers led by the Harvard & Smithsonian Center for Astrophysics (CfA) has now mapped the Local Bubble with the highest precision yet – and found that the Local Bubble was likely carved out of the interstellar medium by a series of supernova explosions millions of years ago.

This is consistent with previous studies, with an additional sting in the tail: the still-expanding Local Bubble is responsible for regions of heightened star formation at its perimeter.

"This is really an origin story; for the first time we can explain how all nearby star formation began," says astronomer Catherine Zucker of the Space Telescope Science Institute, who conducted the research while at the CfA.

The Local Bubble was only discovered relatively recently, in the 1970s and 1980s, through a combination of optical, radio, and X-ray astronomy. Gradually, these surveys and observations revealed a huge region about 10 times less dense than the average interstellar medium in the Milky Way galaxy.

Since we know supernovae can carve out cavities in space, sweeping up gas and dust as they expand outwards, this seemed a reasonable explanation for the Local Bubble.

But piecing together how and when was more tricky. It's hard, for one thing, to measure the dimensions of a region of space when you're inside it; and doubly hard to measure a void when you're surrounded by bright stars and other cosmic objects.

Zucker and her team used data from the most recent Gaia data release – an ongoing project to map the positions and motions of stars in the Milky Way with the highest precision yet – to map the gas and young stars within 200 parsecs (around 650 light-years) of the Sun.

They found that all young stars and star-forming regions are on the "surface" of the Local Bubble.

This makes sense; as a supernova expands outwards, it shocks and compresses the material it expands into. This creates dense knots in molecular gas floating in the interstellar medium that collapse under their own gravity to form baby stars.

Next, the researchers conducted simulations and tracebacks of the motions of star-forming regions to model the Bubble's expansion. This allowed them to reconstruct its history, matching the outcomes of their calculations against their map of the bubble.

Originally published on https://www.sciencealert.com

COMING UP!!

(Saturday, October 4th, 2025)

"WHY DOES STARS TWINKLE AND PLANETS DO NOT??"