If the thought of receiving radio signals from space conjures an image of Jodie Foster in the movie Contact, huddled over a computer console and eagerly listening for spaceship schematics transmitted from intelligent beings in the Vega star system, consider this a fascinating starting point for grasping what scientists envision when they tune into the cosmic radio waves. The reality of these endeavors may lack the dramatic flair of Hollywood, but it is far from dull. Scientists are engaged in a profound exploration of the universe that encompasses a wide range of phenomena and signals, all providing invaluable insights into the workings of our cosmos.

Radio telescopes, renowned for their groundbreaking work, include the iconic Arecibo Observatory in Puerto Rico and numerous installations scattered across deserts around the globe. However, it’s essential to clarify that these telescopes are not primarily designed to detect intentional communication signals from extraterrestrial life. This would be akin to stating that our eyes are solely for spotting rabid grizzly bears; while that may not be entirely inaccurate, it does not capture the true purpose of their existence. Instead, these instruments serve as essential tools for unraveling the mysteries of the universe, capturing invaluable data about a variety of cosmic phenomena.

In essence, radio telescopes function somewhat like our eyes; rather than simply “listening” as the term “radio” might imply, they are more accurately observing what is often referred to as the “radio sky.” This term encompasses the myriad detectable emissions produced by cosmic objects from our perspective on Earth. Among these emissions are pulsar beacons, solar flares and their impacts on our planet, and the pervasive microwave background radiation that fills the universe. Furthermore, the radio sky captures signals from nearer sources, such as spacecraft exploring our solar system and the satellites that orbit our planet, providing a comprehensive view of the cosmos.

In 2024, the radio receivers situated on and around Earth collected a wealth of intriguing emissions. Many of these signals remain shrouded in mystery, but none are likely to originate from space invaders. Instead, they provide a treasure trove of data that is arguably more captivating than anything fiction could conjure. Here are five of the most compelling radio signals recorded in 2024:

Discovering the Enigma of a Mysteriously Slow Pulse

One of the standout discoveries of 2024 was the detection of a perplexing signal known as ASKAP J193505.1+214841.0, which was identified by the Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope. Although this signal was initially spotted prior to this year, the research team published their findings in June 2024. What makes this signal particularly enigmatic is its unique characteristic of repeating almost hourly — specifically every 53.8 minutes. This frequency is far too slow for anything currently understood by astronomers, leaving scientists scratching their heads in search of answers.

The intervals between emissions from ASKAP J193505.1+214841.0 are too prolonged to be attributed to pulsars, which are known to emit signals from rapidly rotating neutron stars, achieving extraordinarily high rotational speeds. The unprecedented duration of this newly discovered signal gap has left scientists bewildered, yet it is important to note that every great scientific discovery often begins with the identification of something that appears “impossible.” This ongoing research may eventually unlock new understandings of cosmic phenomena.

Unraveling the Mystery of a Powerful, Distant Burst

Imagine metaphorically “staring” at the radio sky. For radio astronomers, the radio wave bursts known as fast radio bursts (FRBs) can be likened to quick, blinding flashes that momentarily overpower all other signals before vanishing just as quickly. One such astonishing burst is FRB 20220610A, which remarkably traversed the cosmos for an astounding 8 billion years before being detected on Earth. To put this into perspective, the Big Bang occurred approximately 13.8 billion years ago, making this signal one of the oldest ever captured.

Not only is FRB 20220610A one of the most distant FRBs ever observed, but it also ranks among the “brightest” (or most energetic) radio signal bursts recorded by humanity’s instruments. This exceptional signal was detected by ASKAP, with the assistance of the Hubble Space Telescope, and its source may have originated from a region in space where “as many as seven galaxies on a possible path to merging” were detected, according to a NASA blog post detailing this remarkable discovery.

Addressing Radio Pollution from Starlink Satellites

In recent years, researchers have raised concerns about the disruptive signals emitted by the over 6,000 SpaceX-operated Starlink satellites currently orbiting Earth, which transmit data to internet users on the planet’s surface. The signals from these satellites can create unwanted noise that interferes with specific instruments used to observe the radio sky. However, a 2024 study conducted by researchers at the Netherlands’ LOFAR observatory revealed that the latest V2-mini line of satellites emits up to 32 times more unwanted noise than previous Starlink models.

This increase in Starlink noise is obstructing astronomers’ ability to detect certain low-frequency signals essential for studying exoplanets, black holes, and ancient cosmic phenomena. Regulatory measures do exist to protect radio telescopes from such interference, with designated radio quiet zones established for their benefit. However, these zones are primarily enforced against interference from nearby mobile phones and do not account for the noise generated by objects launched into space. The emissions from satellites represent an unregulated area, and with Starlink having deployed around 6,000 satellites into this regulatory void, the implications for astronomical research are significant. Thanks as always, Elon!

Uncovering Clues from Another FRB for Scientists

Another noteworthy FRB is providing critical insights into the enigmatic origins of massive radio signal bursts in 2024. This significant finding stems from research centered around phenomena known as magnetars. Specifically, magnetar SGR 1935+2154 emitted its intriguing signal back in 2020, and after pinpointing its source, the research team at Caltech’s Deep Synoptic Array-110 (DSA-110) concluded that such signals originate from neutron stars located within massive, star-forming galaxies rich in metals. This revelation significantly narrows the possibilities for identifying neutron stars capable of producing FRB-generating attributes, leading to a more precise understanding of where these extreme cosmic events occur.