The study of the universe as a whole
Star formation peaked during the Cosmic Noon, which spanned from 10 to 12 billion years ago. During Cosmic Noon, star formation was 10 to 100 times greater than it is now. New research shows that a particular class of galaxy was experiencing its first intense burst of star formation during this time. Were these galaxies the progenitors of galaxies like the Milky Way?
The early universe was shrouded in darkness. Just hundreds of millions of years after the Big Bang, a thick fog of hydrogen gas choked the cosmos, blocking light from traveling far. At some point, this gas became ionized, stripped of its electrons. Thanks to the James Webb Space Telescope, astronomers have identified the culprit: low-mass starburst galaxies emitting huge amounts of ultraviolet light. In just one patch of sky. They discovered 83 of these galactic powerhouses in one part of the sky at a time when the Universe was only 800 million years old.
An international team of astronomers using the [*Cosmology Large Angular Scale Surveyor*](https://sites.krieger.jhu.edu/class/) (CLASS) [reported the first-ever measurement](https://hub.jhu.edu/2025/06/11/telescopes-look-at-cosmic-dawn/) announced the first-ever detection of radiation from the cosmic microwave background (CMB) interacting with the first stars in the Universe.
The Hubble Deep Field revolutionised astronomy by staring at a seemingly empty patch of sky for thousands of hours, unveiling a cosmos teeming with distant galaxies. But even Hubble can't peer back far enough to witness the universe's first moment of illumination; the Cosmic Dawn, when primordial darkness gave way to starlight. Now, the Square Kilometre Array promises to shatter that barrier. In a groundbreaking simulation, researchers have modelled 1000 hours of SKA observations, creating astronomy's next great deep field, one designed to capture the universe's very first sunrise.
The COSMOS scientific collaboration has released the largest map of the Universe ever created. It contains almost 800,000 galaxies, some from the Universe's earliest times. The map challenges some of our ideas about the early Universe.
For years, scientists have been scratching their heads over the "Hubble Tension,” the mismatch between how fast the cosmos was expanding in its youth versus how fast it's expanding today. But now, armed with the most precise data ever captured by the James Webb Space Telescope, astronomers have found the perceived gap is starting to narrow! In fact, the expansion rate measured by Cepheid variables versus the cosmic background has overlapping error bars again. Will the tension mystery finally be resolved?
In a recent paper, an international team proposed an ultra-long wavelength radio interferometer that could examine the Cosmic Dark Ages and Cosmic Dawn. Known as the Dark Ages Explorer (DEX), this telescope could provide fresh insights into how and when the first stars and galaxies formed.
For a while now, there has been a problematic mystery at the heart of the standard cosmological model. Although all observations support the expanding Universe model, observations of the early period of the cosmos give a lower rate of acceleration than more local observations. We call it the Hubble tension problem, and we have no idea how to solve it. Naturally, there have been several proposed ideas: what if general relativity is wrong; what if dark matter doesn't exist; what if the rate of time isn't uniform; heck, what if the entire Universe rotates. So, let's add a new idea to the pile: what if dark matter evolves?
The Cosmic Microwave Background is one of the bedrock pieces of evidence for the Big Bang. It's described as the cosmic afterglow from the Universe's birth. However, new research calls into question our understanding of the CMB and what it tells us about the evolution of the Universe.
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We don't have to rely solely on the JWST to observe the Universe's oldest stars. Some of the oldest stars in the Universe reside in globular clusters, and the Milky Way has about 150 of them. How old exactly? New research has the answer.
Has your dinner time conversations been dragging a bit of late? Feel like raising its knowledge level to a bit higher than the usual synopsis of the most recent reality TV show? Then take the challenge presented by Sean Carroll in his book "The Biggest Ideas in the Universe – Space, Time and Motion". Using this, your conversation might soon be sparkling with grand thoughts about modern physics, time travel, going faster than light and the curvature of the universe.
About 380,000 years after the Big Bang, the first atoms formed. The first light of what we now see as the cosmic microwave background was released, and the primordial hydrogen and helium grew cold and dark. The cosmos entered a dark age for about 100 million years until the first stars and galaxies started to form. You could say the rise of galaxies marked cosmic morning. But star formation didn't really kick into gear for another 2-3 billion years, during what astronomers call cosmic noon. This period can be difficult to observe, but a new study gives us an unprecedented view of this epoch.
Everything in the Universe spins. Galaxies, planets, stars, and black holes all rotate, even if just a bit. It comes from the fact that the clouds of scattered gas and dust of the cosmos are never perfectly symmetrical. But the Universe as a whole does not rotate. Some objects spin one way, some another, but add them all up, and the total rotation is zero. At least that's what we've thought. But a new study suggests that the Universe does rotate, and this rotation solves the big mystery of cosmology known as the Hubble tension.
One of the things about astronomy that captivates me is that for every question we answer, we open up a whole bunch of other questions. Dark matter and dark energy are one such phenomenon that rather continues to confound us. There's also the mystery of missing infrared light too but a team of astronomers think they may have found it! The team examined a region of sky using the Herschel Space Telescope and, by staking 141 images, found where individual dust-rich galaxies appeared blended together. The galaxies are absorbing starlight and re-emitting infrared radiation, and is this that may well account for the missing light.
When galaxies run out of primordial hydrogen and helium, they cease star formation, shifting to primarily long-lived red stars. These galaxies are considered "red and dead." It usually takes billions of years for galaxies to run out of hydrogen, but now astronomers using JWST have found examples of galaxies that have already stopped forming stars just 700 million years after the Big Bang, much earlier than predicted by cosmological models.
When the James Webb Space Telescope was launched in December 2021, one of its primary purposes was to see the first galaxies in the Universe forming just a few million years after the Big Bang. In true JWST style though, it has surpassed all expectations and now, a team of astronomers think they have gone even further back, seeing one galaxy clearing the early fog that obscured the Universe! The image represents a point in time 330 million years after the Big Bang and reveals a bright hydrogen emission from the fog surrounding a galaxy. It was somewhat unexpected though as current models predict it would have been blown away long ago!
Dark matter is a confounding concept that teeters on the leading edges of cosmology and physics. We don't know what it is or how exactly it fits into the Standard Cosmological Model. We only know that its unseen mass is a critical part of the Universe.
It's looking more and more as if dark energy, the mysterious factor that scientists say is behind the accelerating expansion of the universe, isn't as constant as they once thought. The latest findings from the Dark Energy Spectroscopic Instrument, or DESI, don't quite yet come up to the level of a confirmed discovery, but they're leading scientists to rethink their views on the evolution of the universe — and how it might end.
One of the Holy Grails in cosmology is a look back at the earliest epochs of cosmic history. Unfortunately, the Universe's first few hundred thousand years are shrouded in an impenetrable fog. So far, nobody's been able to see past it to the Big Bang. As it turns out, astronomers are chipping away at that cosmic fog by using data from the Atacama Cosmology Telescope (ACT) in Chile.
Universe Today