Habitable Worlds Could Have Formed Before the First Galaxies

This artist’s impression shows the planet K2-18b, it’s host star and an accompanying planet in this system. K2-18b is now the only super-Earth exoplanet known to host both water and temperatures that could support life. Could habitable worlds like this have formed before galaxies formed? Image Credit: ESA/Hubble, M. Kornmesser

What came first, galaxies or planets? The answer has always been galaxies, but new research is changing that idea.

Could habitable planets really have formed before there were galaxies?

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Hubble Takes a 2.5 Gigapixel Image of Andromeda

This the largest photomosaic ever assembled from NASA/ESA Hubble Space Telescope observations. It is a panoramic view of the neighboring Andromeda galaxy, located 2.5 million light-years away. Image Credit: NASA, ESA, B. Williams (University of Washington)

The Andromeda galaxy is our closest galactic neighbour, barring dwarf galaxies that are gravitationally bound to the Milky Way. When conditions are right, we can see it with the naked eye, though it appears as a grey smudge. It’s the furthest object in the Universe that we can see without telescopic help.

The Hubble Space Telescope has created a massive 2.5-gigapixel panorama of Andromeda. It took 10 years and more than 1,000 orbits to capture all of the images.

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Astronomers are Watching a Newly Forming Super Star Cluster

An artist impression of young star formation in the Large Magellanic Cloud. Massive and low-mass stars appear within nebulous gas within which they are born. Credit: NSF/AUI/NSF NRAO/S.Dagnello

Six or seven billion years ago, most stars formed in super star clusters. That type of star formation has largely died out now. Astronomers know of two of these SSCs in the modern Milky Way and one in the Large Magellanic Cloud (LMC), and all three of them are millions of years old.

New JWST observations have found another SSC forming in the LMC, and it’s only 100,000 years old. What can astronomers learn from it?

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Sticks and Stones: The Molecular Clouds in the Heart of the Milky Way

Astronomers have created 3D maps of two giant molecular clouds in the Milky Way's Central Molecular Zone (CMZ). What happens to them in such an extreme environment? Image Credit: Alboslani et al. 2025.

The Central Molecular Zone (CMZ) at the heart of the Milky Way holds a lot of gas. It contains about 60 million solar masses of molecular gas in complexes of giant molecular clouds (GMCs), structures where stars usually form. Because of the presence of Sag. A*, the Milky Way’s supermassive black hole (SMBH), the CMZ is an extreme environment. The gas in the CMZ is ten times more dense, turbulent, and heated than gas elsewhere in the galaxy.

How do star-forming GMCs behave in such an extreme environment?

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The Most Accurate View of the Milky Way

Gaia showed us that our galaxy's disk, the dark brown horizontal spanning from one side to the other, has a bit of a wave to it. Gaia also showed us that the Milky Way has more than two spiral arms and that they aren't as pronounced as we thought. Image Credit: ESA/Gaia/DPAC, Stefan Payne-Wardenaar CC BY-SA 3.0 IGO

We can judge the value of any scientific endeavour based on how much of our knowledge it overturns or transforms. By that metric, the ESA’s Gaia mission is a resounding success. The spacecraft gave us a precise, 3D map of our Milky Way galaxy and has forced us to abandon old ideas and replace them with compelling new ones.

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The Gaia Mission’s Science Operations are Over

ESA’s Milky Way-mapper Gaia has completed the sky-scanning phase of its mission, racking up more than three trillion observations of about two billion stars and other objects over the last decade to revolutionise our view of our home galaxy and cosmic neighbourhood.

The ESA has announced that Gaia’s primary mission is coming to an end. The spacecraft’s fuel is running low, and the sky-scanning phase of its mission is over. The ground-breaking mission has taken more than three trillion observations of two billion objects, mostly stars.

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About a Third of Supermassive Black Holes are Hiding

A supermassive black hole surrounded by a torus of gas and dust is depicted in four different wavelengths of light in this artist’s concept. Visible light (top right) and low-energy X-rays (bottom left) are blocked by the torus; infrared (top left) is scattered and reemitted; and some high energy X-rays (bottom right) can penetrate the torus. Image Credit: NASA/JPL-Caltech

Supermassive black holes can have trillions of times more mass than the Sun, only exist in specific locations, and could number in the trillions. How can objects like that be hiding? They’re shielded from our view by thick columns of gas and dust.

However, astronomers are developing a way to find them: by looking for donuts that glow in the infrared.

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Webb Provides an Explanation for “Little Red Dots”

A team of astronomers sifted through James Webb Space Telescope data from multiple surveys to compile one of the largest samples of “little red dots” (LRDs) to date. From their sample, they found that these mysterious red objects that appear small on the sky emerge in large numbers around 600 million years after the big bang and undergo a rapid decline in quantity around 1.5 billion years after the big bang. Image Credit: NASA, ESA, CSA, STScI, Dale Kocevski (Colby College)

When a new space telescope is launched, it’s designed to address specific issues in astronomy and provide critical answers to important questions. The JWST was built with four overarching science goals in mind. However, when anticipating new telescopes, astronomers are quick to point out that they’re also excited by the unexpected discoveries that new telescopes make.

There has been no shortage of unexpected discoveries regarding the JWST, especially regarding the very early Universe.

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The Webb Shows Us Where Cosmic Dust Comes From

Concentric rings of dust form around the pair of binary stars named Wolf-Rayet 140. The dust is formed when the stellar winds from the stars slam into each other every few years. Image Credit: NASA, ESA, CSA, STScI, JPL-Caltech

Carbon-rich cosmic dust comes from different sources and spreads out into space, where it’s necessary for life and for the formation of rocky planets like ours. When astronomers aim their telescopes at objects in the sky, they often have to contend with this cosmic dust that obscures their targets and confounds their observations.

One reason the JWST was built is to see through some of this dust with its infrared vision and unlock new insights into astrophysical processes. In new work, the JWST was tasked with observing the dust itself.

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Gravitational Waves Could Give Us Insights into Fast Radio Bursts

This artist's illustration shows a neutron star with a powerful magnetic field, a magnetar. Scientists want to know if magnetars can generate both Fast Radio Bursts and Gravitational Waves. Image Credit: ESO/L. Calçada

Fast Radio Bursts (FRBs) are mysterious pulses of energy that can last from a fraction of a millisecond to about three seconds. Most of them come from outside the galaxy, although one has been detected coming from a source inside the Milky Way. Some of them also repeat, which only adds to their mystery.

Though astrophysicists think that a high-energy astrophysical process is the likely source of FRBs, they aren’t certain how they’re generated. Researchers used gravitational waves (GWs) to observe one nearby, known source of FRBs to try to understand them better.

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