Most likely, you pictured some human-like figure, maybe with a big head, big eyes, and green or grey skin. Why is this the image we always jump to when we hear aliens.

Moreover, you may think of a hostile race, that wants to come to Earth to take over. Maybe it is for our resources, maybe it is to colonise, or maybe we do know why, but we should fear and fight them.

Humans are a very self-centred species - we think a lot of ourselves. We think that the world, and by extension other worlds, revolve around us. Therefore, we think that all life on other planets must look, act, and think like us. They would also want we have, and it is up to us to defend ourselves.

This view doesn't come from science, but science fiction. Movies, TV shows, and novels have created and built up this stereotype, embedding it into our culture. When H.G. Wells wrote War of the Worlds in the late 19th century, Wells created a view of aliens that has stuck with us to this day.

In War of the Worlds, big-headed creatures with tentacles that operated machines came from Mars to colonise Earth. The book was rooted in science, but also a critique of the world at the time.

Wells was strongly against British colonialism and the issues, especially for indigenous peoples around the world, it created. In one passage, Wells even refers to Tasmania, saying that why should Earthlings condemn the Martians when we have done similar things on Earth, using Tasmania as an example.

War of the Worlds is using the idea of beings from other worlds as a way to tell and critique what is happening in the world. We should actually fear ourselves.

This view, both physically how aliens look, and how they act, is repeated over and over in science fiction. From Independence Day to Mars Attacks. Even in films like Arrival, the aliens look similar to classic portrayals and, while not meant to be hostile, we automatically assume they are.

When aliens seemingly visit us here on Earth, they are hostile creatures out to harm or take over our planet. When we Earthlings travel and explore other worlds and meet aliens there, we are innocent explorers. How come it is not the reverse? It is a matter of projection - we are projecting our own worries and fears, not necessarily scientific ones.

Even prominent scientists like the late Stephen Hawking have warned we should not contact an alien species as they are likely to be hostile. We worry about aliens, but should we?

Most alien life is likely, if it exists at all, to be simple, like bacteria. We forget that most of the life on our own planet is not us, but everything else. Plants, dogs, bacteria, fish are all life and make up the majority of this planet. Then there is also the life that has been in the past, and will be in the future.

The next time you think of aliens, first try think of all the life that exists on Earth. And instead of thinking about it being hostile or dangerous, realise it is the aliens that should be afraid of us.