Do Aliens Really Exist?

For thousands of years, humans have looked up at the night sky and asked the same question: are we alone? Ancient civilisations drew pictures of strange beings in their art and told stories about visitors from the sky. The ancient Egyptians, the Mayans of Central America, and many other early cultures created images that some people today think look like astronauts or flying machines. Of course, most historians say these are simply the way those cultures drew gods and spirits — but the mystery still excites people's imaginations.

In the twentieth century, the question became more serious. Scientists began to understand how enormous the universe really is. Our planet Earth orbits one star — the Sun. But our galaxy, the Milky Way, contains over two hundred billion stars. And astronomers now believe there are more galaxies in the observable universe than there are grains of sand on all the beaches of Earth. With so many stars and so many planets, many scientists believe it would be very strange if Earth were the only place where life developed. As the famous Italian physicist Enrico Fermi once asked: if the universe is so big and old, where is everybody?

The modern story of UFOs — Unidentified Flying Objects — really began in 1947. In June of that year, an American pilot called Kenneth Arnold reported seeing nine bright objects flying at incredible speed near Mount Rainier in Washington State. He described them moving like a saucer if you skipped it across water, and newspapers quickly called them "flying saucers." The term became famous around the world almost immediately.

Just weeks later, in July 1947, something crashed in the desert near Roswell, New Mexico. The US Army Air Force first announced they had recovered a "flying disc" — but the next day they changed the story and said it was just a weather balloon. This change of story made many people suspicious. For decades, people who believed in UFOs claimed that the US government had found a crashed alien spacecraft and kept it secret. The US government officially denied this. However, in 2021, the American government released a report about what it calls UAPs — Unidentified Aerial Phenomena — admitting that military pilots had recorded many objects in the sky that could not be easily explained. It was the most serious official statement about UFOs in history, and it changed the conversation completely.

While some people look for aliens in old photographs or UFO reports, scientists are searching in a very different way. NASA and other space agencies have sent rovers to Mars to look for signs that life may have existed there billions of years ago. Mars once had liquid water on its surface, and water is one of the key ingredients scientists believe life needs to develop. So far, no direct evidence of past or present life on Mars has been found — but the search continues.

Scientists have also discovered thousands of exoplanets — planets that orbit stars other than our Sun. Some of these planets are in what scientists call the "habitable zone" — the area around a star where the temperature is right for liquid water to exist. One programme called SETI — the Search for Extraterrestrial Intelligence — has been listening to radio signals from space since the 1960s, hoping to detect a message from another civilisation. In 1977, a radio telescope in Ohio picked up a strong, unusual signal from space that became known as the "Wow! Signal" — scientists have never been able to fully explain it. The search for intelligent life remains one of the most exciting scientific projects in human history.

Most people imagine aliens the way they appear in movies — with large heads, big eyes, and humanoid bodies. But scientists think this is very unlikely. Life on Earth took billions of years to develop, and it was shaped by very specific conditions on our planet. Life on another world would develop under completely different conditions, with different gravity, different chemicals, different temperature, and different light from a different star. It might look nothing like anything we have ever seen — or it might be so different from us that we would not even recognise it as life.

Many scientists now believe that if we find life beyond Earth, it will most likely be microbial — extremely tiny, single-celled organisms similar to bacteria. This would still be one of the greatest discoveries in human history. But the possibility of intelligent life — beings that can think, communicate, and build technology — raises much bigger questions. How would we communicate with them? What would we say? And perhaps most importantly: would contact with another intelligent species be a wonderful moment of connection, or would it be dangerous? Some scientists, including the late Stephen Hawking, warned that it might be unwise to try to make contact — pointing out that when technologically advanced civilisations meet less advanced ones on Earth, it has rarely ended well for the less advanced group.