The Stellar Demolition Derby in the Centre of the Galaxy

This illustration shows stars orbiting close to the Milky Way's central supermassive black hole. The black hole accelerates stars nearby and sends them crashing into one another. Credit: ESO/L. Calçada/

The region near the Milky Way’s centre is dominated by the supermassive black hole that resides there. Sagittarius A*’s overwhelming gravity creates a chaotic region where tightly packed, high-speed stars crash into one another like cars in a demolition derby.

These collisions and glancing blows change the stars forever. Some become strange, stripped-down, low-mass stars, while others gain new life.

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New Moons Found at Uranus and Neptune

The discovery image of the new Uranian moon S/2023 U1 using the Magellan telescope on November 4, 2023. Uranus is just off the field of view in the upper left, as seen by the increased scattered light. S/2023 U1 is the faint point of light in the center of the image with the yellow arrow. The trails are from background stars. Credit: Scott Sheppard.

Astronomers have found three new moons orbiting our Solar System’s ice giants. One is orbiting Uranus, and two are orbiting Neptune. It took hard work to find them, including dozens of time exposures by some of our most powerful telescopes over several years. All three are captured objects, and there are likely more moons around both planets waiting to be discovered.

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Astronomers See the Afterglow Where Two Ice Giant Planets Collided

This artist's illustration is a visualization of the huge, glowing planetary body produced by a planetary collision. In the foreground, fragments of ice and rock fly away from the collision and will later cross in between Earth and the host star which is seen in the background of the image. Image Credit: Mark Garlick

What would happen if two giant planets collided? It would be terrifying to behold if it happened in our Solar System. Imagine if Neptune and Uranus slammed into each other. Picture the chaos as a new super-heated object took their places, and clouds of debris blocked out the Sun. Think of the monumental destruction as objects are sent careening into each other.

Astronomers spotted the aftermath of a gigantic planetary collision like this in a distant solar system. From a safe distance, they were surprised and intrigued rather than terrified. Now, they intend to keep watching as the aftermath unfolds.

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Colliding Moons Might Have Created Saturn’s Rings

Saturn's rings are arguably the most recognizable feature in our Solar System and are made mostly of ice particles. New research says a collision between icy moons may have created them in the recent past. Image Credit: NASA/JPL/Space Science Institute

If we could wind the clock back billions of years, we’d see our Solar System the way it used to be. Planetesimals and other rocky bodies were constantly colliding with each other, and new objects would coalesce out of the debris. Asteroids rained down on the planets and their moons. The gas giants were migrating and contributing to the chaos by destroying gravitational relationships and creating new ones. Even moons and moonlets would’ve been part of the cascade of collisions and impacts.

When nature crams enough objects into a small enough space, it breeds collisions. A new study says that’s what happened at Saturn and created the planet’s dramatic rings.

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The Case of the “Missing Exoplanets”

An illustration of the variations among the more than 5,000 known exoplanets discovered since the 1990s. Could their stars' metallicity play a role in making them habitable to life? Credit: NASA/JPL-Caltech
An illustration of the variations among the more than 5,000 known exoplanets discovered since the 1990s. Could their stars' metallicity play a role in making them habitable to life? Credit: NASA/JPL-Caltech

Today, the number of confirmed exoplanets stands at 5,197 in 3,888 planetary systems, with another 8,992 candidates awaiting confirmation. The majority have been particularly massive planets, ranging from Jupiter and Neptune-sized gas giants, which have radii about 2.5 times that of Earth. Another statistically significant population has been rocky planets that measure about 1.4 Earth radii (aka. “Super-Earths”). This presents a mystery to astronomers, especially where the exoplanets discovered by the venerable Kepler Space Telescope are concerned.

Of the more than 2,600 planets Kepler discovered, there’s an apparent rarity of exoplanets with a radius of about 1.8 times that of Earth – which they refer to as the “radius valley.” A second mystery, known as “peas in a pod,” refers to neighboring planets of similar size found in hundreds of planetary systems with harmonious orbits. In a study led by the Cycles of Life-Essential Volatile Elements in Rocky Planets (CLEVER) project at Rice University, an international team of astrophysicists provide a new model that accounts for the interplay of forces acting on newborn planets that could explain these two mysteries.

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This is How You Get Moons. An Earth-Sized World Just got Pummeled by Something Huge.

An MIT-led team has discovered evidence of a giant impact in the nearby HD 17255 star system, in which an Earth-sized terrestrial planet and a smaller impactor likely collided at least 200,000 years ago, stripping off part of one planet’s atmosphere. Credits:Image: Mark A. Garlick

Titanic collisions are the norm in young solar systems. Earth’s Moon was the result of one of those collisions when the protoplanet Theia collided with Earth some 4.5 billion years ago. The collision, or series of collisions, created a swirling mass of ejecta that eventually coalesced into the Moon. It’s called the Giant Impact Hypothesis.

Astronomers think that collisions of this sort are a common part of planet formation in young solar systems, where things haven’t settled down into predictability. But seeing any of these collisions around other stars has proved difficult.

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A Black Hole or Neutron Star Fell Into Another Star and Triggered a Supernova

Artist's conception of the ring of material surrounding a star shortly after engulfing a dense companion. Credit: Bill Saxton, NRAO/AUI/NSF

What happens when you slam a neutron star (or black hole, take your pick) into a companion star? A supernova, that’s what. And for the first time ever, astronomers think they’ve spotted one.

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When Galaxies Collide, Black Holes Don’t Always Get the Feast They Were Hoping for

galaxies collide
This illustration shows a stage in the predicted merger between our Milky Way galaxy and the neighboring Andromeda galaxy, as it will unfold over the next several billion years. In this image, representing Earth's night sky in 3.75 billion years, Andromeda (left) fills the field of view and begins to distort the Milky Way with tidal pull. (Credit: NASA; ESA; Z. Levay and R. van der Marel, STScI; T. Hallas; and A. Mellinger)

What happens when galaxies collide? Well, if any humans are around in about a billion years, they might find out. That’s when our Milky Way galaxy is scheduled to collide with our neighbour the Andromeda galaxy. That event will be an epic, titanic, collision. The supermassive black holes at the center of both galaxies will feast on new material and flare brightly as the collision brings more gas and dust within reach of their overwhelming gravitational pull. Where massive giant stars collide with each other, lighting up the skies and spraying deadly radiation everywhere. Right?

Maybe not. In fact, there might be no feasting at all, and hardly anything titanic about it.

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About 3% of Starlinks Have Failed So Far

An artist's conception of Starlink in orbit. Credit: SpaceX

SpaceX has drawn plenty of praise and criticism with the creation of Starlink, a constellation that will one-day provide broadband internet access to the entire world. To date, the company has launched over 800 satellites and (as of this summer) is producing them at a rate of about 120 a month. There are even plans to have a constellation of 42,000 satellites in orbit before the decade is out.

However, there have been some problems along the way as well. Aside from the usual concerns about light pollution and Radio Frequency Interference (RFI), there is also the rate of failure these satellites have experienced. Specifically, about 3% of its satellites have proven to be unresponsive and are no longer maneuvering in orbit – which could prove hazardous to other satellites and spacecraft in orbit.

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Astronomers See the Wreckage from a Collision Between Exoplanets

RArtist’s concept illustrating a catastrophic collision between two rocky exoplanets in the planetary system BD +20 307, turning both into dusty debris. Credits: NASA/SOFIA/Lynette Cook

The history of our Solar System is punctuated with collisions. Collisions helped create the terrestrial planets and end the reign of the dinosaurs. And a massive collision between Earth and an ancient body named Theia likely created the Moon.

Now astronomers have found of evidence of a collision between two exoplanets in a distant solar system.

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