Looking into the cosmos is like peeking into the universe’s past. Everything that NASA and other space agencies observe, whether it’s thousands, millions, or even billions of light-years away, has already happened. We’re only seeing it now because light takes time to travel to Earth. In a way, we’re always late to the universe’s breaking news. Yet, light eventually reaches us, revealing new cosmic objects and reminding us that our understanding of the cosmos is still just a fraction of the whole.
It happened billions of years ago, but only reached Earth recently
This signal has been traveling towards Earth for 11 billion years – and we were only capable of unveiling the meaning recently. As this event took place a couple of years after the big expansion, in cosmic timescales, it means that it was right after – it also took an additional 11 billion years to arrive on our planet due to the speed of light.
As NASA develops ever more powerful tools, scientists are sending telescopes into space, deploying rovers on Mars, and launching probes to distant regions. They’re also investing in Earth-based observatories to aid discoveries–and sometimes make their own. Recently, South Africa’s MeerKAT radio telescope array picked up a radio signal from a time when most galaxies were not around.
The most distant radio signal in history: It’s from the beginning of the universe
Using the MeerKAT radio telescope, an international team of astronomers discovered a new fast radio burst, FRB 20240304B. Its measured redshift makes it the most distant FRB known so far. The findings were shared in a research paper posted on arXiv on August 3.
Fast radio bursts (FRBs) are extremely brief flashes of radio waves lasting just a few milliseconds. While their exact origins remain a mystery, astronomers suggest possibilities ranging from emissions from young magnetars in supernova remnants to cosmic string cusps. Most FRBs detected until now have been relatively nearby, with redshifts below 0.5, making high-redshift discoveries like FRB 20240304B especially valuable for studying galaxy formation in the early universe.
The discovery that started everything: It saw further into the past than anything
FRB 20240304B was spotted on March 4, 2024, by the Transient User Supplied Equipment (TUSE) on the MeerKAT telescope. Its properties include a dispersion measure of 2,458.20 pc/cm³, a peak flux of 0.49 Jy, and a scattering time of 5.6 milliseconds at 1 GHz. The discovery not only sets a new record for distance but also marks the first FRB detected during cosmic noon, roughly 10–11 billion years ago, when star formation was at its peak.
The discovery also shows that the universe’s magnetic fields are surprisingly complex, stretching across billions of light-years. The path of the burst passed near structures like the Virgo Cluster and other foreground groups, and each of these left its mark on the signal as it traveled to Earth, like in the one captured by Chandra not long ago.
What was happening during this time in the universe: The first light
Even more interesting, this FRB proves that such bursts were happening during the universe’s peak of star formation. It also highlights how FRBs can be used to study galaxy formation during the most active periods in cosmic history.
According to graphics about the history of our universe, after the Big Bang, there was a period of thousands of years in which the cosmos was in total darkness, called the dark age. A billion years into the big expansion, things got bright faster: the Era of Reionization happened, when the radiation of the first stars and galaxies changed the universe by turning neutral hydrogen gas into ionized plasma, and allowed light to travel freely – making the cosmos transparent for the first light.