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Aliens: Astronomy’s Most Puzzling Mystery

  • Writer: Sophia Yang
    Sophia Yang
  • Sep 19
  • 5 min read

Scientists have captured black holes, discovered new planets and everything, but why haven’t they found any evidence of extraterrestrials yet? Extraterrestrial creatures, often referred to as "aliens", have been a prominent and recurring theme in science fiction, from E.T, The X-Files, to Men in Black etc. Fiction has consistently depicted aliens arriving on Earth as either friends or foes; however, to date, no one has definitively shown that they have encountered an alien, nor has such an encounter been scientifically verified. While these portrayals may appear fictional, one may wonder whether such beings are real and exist somewhere within the universe.


Could there be countless sentient life forms out there just waiting to be found? Will we meet them someday and be able to exchange knowledge? Will we even recognize them as intelligent life forms if/when we meet them?


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2. A Galaxy Full of Possibilities

Before we get to the long-awaited answer, let’s start with a quick astronomy lesson. The Milky Way, a spiral galaxy with a disk of stars that stretches over 100,000 light-years contains hundreds of billions of stars, with each star, on average, believed to host at least one exoplanet. An exoplanet is any planet beyond the solar system; more than 5,800 exoplanets out of the billions have been confirmed to exist in the galaxy. (NASA, n.d.) Earth is located along one of the galaxy’s spiral arms, see those little white dots? Yep, that’s where we live, somewhere between those endless stars. 


So, given all these findings, how is it that there is not a single proof of the existence of extraterrestrial life?


3. Where is everybody?

“Where is everybody?”  With just three words, physicist Enrico Fermi posed one of the most profound questions in science. The universe is enormous, ancient, and filled with billions of potentially habitable exoplanets. Yet, despite decades of exploration, the cosmos remains eerily silent. This contradiction is known as the Fermi Paradox, a concept first introduced by Fermi himself in 1950.


The initial reason, and one of the hypotheses associated with the paradox, is that they’re out there, but we haven’t found them yet. Scientists have developed several methods to detect their presence, one of the most prominent is radio signal detection, using large radio telescopes to listen for unusual, non-random signals from space. However, this method has limitations. First, the speed of light, approximately 300.000 kilometers per second, limits how quickly signals, including radio waves, can travel. Although this speed is incredibly fast, space is so vast that even light takes years to traverse certain regions of our galaxy. Meanwhile, the signals we've sent are weak and tend to scatter quickly, making Earth's "cosmic noise" even quieter. In essence, our planetary "hello" to the universe has diminished into a faint whisper, similar to trying to call a number that's been disconnected or sent to voicemail (Amos, 2010)


Two more hypothetical ideas about why we haven't found evidence of extraterrestrial life suggest either that they are intentionally staying quiet or that there are huge challenges preventing their growth. The Zoo Hypothesis and The Dark Forest theory both propose that intelligent extraterrestrial civilizations might choose not to reveal themselves, either to quietly watch us, like animals in a reserve, or to stay hidden because the universe could be dangerous, and any signals they send might lead to their destruction (Dobrijevic, 2025)


One of the most well-known attempts to address the Fermi Paradox is the “Drake Equation” developed by physicist Frank Drake as a way to estimate the probability of extraterrestrial civilizations likely to exist in the Milky Way galaxy. While it has proven to be a durable framework for research and space technology, it is not a reliable tool for calculating the exact number of civilizations, many of its variables are based on speculation and as of now, no direct discoveries of extraterrestrial life from the Drake Equation itself has been found (NASA, 2016) The search for life continues through telescopes, probes, and experiments from SETI (Search for Extraterrestrial Intelligence).making it more of a thought experiment than a precise formula (Weisberger, 2017)


4. If We Can’t Find Them, Can They Find Us?

With the rise of our modern technology and radio signals, new research says that we are actually able to send signals. In April of 2023, Howard T Isaacson, an astrophysicist at UC Berkeley, calculated whether some of these transmissions, up to 20 kilowatts, might reach other stars as they wash over the remote spacecraft and continue their journey into space. He found four nearby stars and any accompanying planets would have already received the transmissions, with more than 1,000 stars likely to hear the signals by the year 2300 (Isaacson & Derrick, 2023)


According to Jonathan Jiang, an astrophysicist from Nasa's Jet Propulsion Laboratory, there is a possibility that alien civilisations with more advanced telescopes might already be able to spot us. “They might have already built a 330ft space telescope that could be seeing us right now" he says. Knowing the tilt and rotation of Earth, they are able to work out if it is inhabited, the light emitted by our planet could be used to make a crude map of our surface, showing land, oceans, and even coastlines (Jiang, 2023)


This raises a mulitude of questions on whether we want to be noticeable or not, as in fictional stories, aliens are perceived as foes or we are the ones being invaded. However, in reality, scientists are eager to make our presence known, occasionally even sending out purposeful messages into the universe (O'Callaghan, 2023) To locate and enable extraterrestrial civilizations to receive our signals we would need a billion times more advanced technologies than we have now. Though this may sound like a lot, society went from one car to over a billion in just a few decades. Therefore, the technologies needed to make ourselves known to the universe might seem impossible now, but progress can happen faster than we imagine.


Written by Keira Aghni Zhillalunissa Rambe

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Destiny T. Wontcheu
Oct 01
Rated 5 out of 5 stars.

Very interesting, particularly the ideas in point 3.

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