The mysterious trail of magnetic fields and electrons connects two clusters of galaxies named Abell 0399 and Abell 0401. The find offers astronomers new insight into the "cosmic web" of filamentary structures that connect distant objects in the universe.
"Until today, a magnetic field had never been observed in the filaments that connect the clusters between them. The filaments of this web are in fact extremely rarefied and difficult to observe," read the statement announcing the findings.

The galaxy clusters' cores (red) can be seen in X-ray-light. They're linked by a thin filament (yellow and blue)
LoFar is a large radio telescope network made up of more than 25 thousand antennas spread over 51 stations, mainly in the Netherlands but also across Europe. It's designed to explore the universe at low radio frequencies.
The findings were published in the journal Science, but there's still a lot to be learned from the groundbreaking discovery, such as whether emissions detected in this connective filament are a common phenomenon in space, beyond galaxy clusters.