New data from the ALMA Radio Telescope Array in Chile has revealed a cloud filled with organic chemicals surrounding a distant star. It's now looking like the ingredients involved in life are common throughout the universe. So, where are all the aliens?
And if we find them, what will they look like?
Methyl cyanide, a complex carbon-based molecule, has been found along with other types of cyanide around the star MWC 480. This star is twice as massive as our sun, located 455 light years from here. It is also a very young star, which is why it is surrounded by a disc of material that has not yet coalesced into planets.
In other words, it is a model of what our own solar system looked like not long after the sun was born more than four billion years ago.
The organics are located in the outer reaches of the cloud, at about the same distance as a swarm of comets called the Oort Cloud that surrounds our own sun. Comets, as we have seen from missions such as Rosetta, also contain organics, and some believe comets could have delivered them, along with water, to the primordial Earth.
Meanwhile, the Curiosity rover has found organics on Mars, as well. And new images from the Mars Reconnaissance Orbiter show that massive glaciers are hidden beneath the red sands of Mars, providing further evidence that Mars was once a warm and much wetter world than it is today.
So, if the chemicals for life are common across the galaxy, and water, essential for life, is everywhere, why haven't we found any alien life-forms out there?
First of all, life is hard to spot from a distance.
Even looking at the Earth from the moon, it is difficult to see signs of life. You would see the blue colour from all the water, as well as changing colours on the land throughout the seasons to suggest vegetation. You could analyze the atmosphere for oxygen and organics, but you wouldn't be able to actually prove there is life on Earth, or what form it is in, unless you landed on the surface and took a close look.
Of course, if you had a radio receiver you could pick up all the noise from our civilization from a distance, but wireless transmissions are a very recent invention by humans. For most of the Earth's history it has been radio silent. So too, it appears, are other planets around other stars.
Nothing has turned up so far, at any rate. No radio signals or pulsing laser beams carrying messages from other civilizations, no sign of plants or vegetation on other planets, not a single microbe or even an alien fossil.
Still, some scientists are optimistic that we will find alien life by 2025.
If we do, the big question is, will it be like us?
To think that aliens will have a humanoid shape is convenient for science fiction movies, but actually somewhat arrogant. Humans are a recent addition to life on Earth. For most of the Earth's history, life has come in vastly different forms.
To get a better idea of what we might find on other worlds, let's again take a look at our own. Here are photos of the 35 main groups, or phyla, that make up animal life on our planet. Pretty weird looking, eh?
Is this what we will find in space, or will life out there be even stranger?