Planets with DUSTY atmospheres are more likely to harbour alien life

Alien life may be common throughout the universe, researchers claim, saying it could be thriving on planets orbiting distance stars with a dusty atmosphere.   

Exoplanets outside the the solar system are less likely to be too hot or cold if they have a dusty atmosphere and are tidally locked, according to the study.

They would look similar to the land depicted in David Lynch’s 1984 sci-fi blockbuster Dune, or Luke Skywalker’s home planet Tatooine in Star Wars.

This discovery, by researchers from the University of Exeter, dramatically extends the number of planets able to host life – and expands the possible habitable zone.    

The dust in the atmosphere of planets orbiting near the inner edge of the habitable zone of red dwarf stars, collects in the atmosphere and stops water leaving.

A visualization of three computer simulations of terrestrial exoplanets, showing winds (arrows) and airborne dust (color scale), with an M-dwarf host star in the background. 

Met office physicist Dr Ian Boutle, based at the University of Exeter, explained: ‘On tidally locked planets – where the same side always faces the star – dust cools it.

‘At the same time, the night-side is kept warmer – therefore widening the habitable zone for such planets to exist in.’

He added: ‘Dust can slow down a planet’s water loss at the inner edge of the habitable zone – and warm planets at the outer edge.’

These tidally locked dusty planets are expected to orbit just inside the habitable zone of most red dwarf stars – the most common star type found in the universe 

These worlds would look similar to the land depicted in David Lynch's 1984 sci-fi blockbuster Dune, or Luke Skywalker's home planet Tatooine in Star Wars (pictured)

These worlds would look similar to the land depicted in David Lynch’s 1984 sci-fi blockbuster Dune, or Luke Skywalker’s home planet Tatooine in Star Wars (pictured)

Also known as the ‘Goldilocks zone’, it is the area where the temperature is just right – by allowing water – essential for life as we know it – to flow on the surface.

On Earth and Mars dust storms have both cooling and warming effects – with the former typically winning out but planets in a synchronised orbit ‘are very different’. 

‘Here, the dark sides are in perpetual night, and the warming effect wins out, whereas on the dayside, the cooling effect wins out,’ said Boutle.

‘The effect is to moderate the temperature extremes, thus making the planet more habitable, similar to the world shown in the sci-fi movie Dune.’

His team performed a series of simulations of rocky, Earth-sized exoplanets using state-of-the-art climate models.

It showed for the first time that naturally occurring mineral dust will have a significant impact on whether an exoplanet can support life.

‘The results highlight the need to consider the potential effects of dust when studying terrestrial exoplanets,’ said Dr Boutle.

This airborne material, mainly comprising particles of carbon-silicate from the surface, effects a climate system. The phenomenon has been ignored, until now.

It makes worlds habitable over a greater range of distances from their star – widening the window for those capable of sustaining life.

Planets orbiting close to suns smaller and cooler than Earth’s, known as M-dwarfs, are likely to exist in ‘synchronised rotation-orbit states’ – resulting in permanent day and night sides – also known as being tidally locked like the Moon.

The experiments by the Met Office researcher, found dust cools down and warms up the hotter day and night sides, respectively.

For planets in general, they suggested cooling by airborne dust plays a significant role at the inner edge of the habitable zone.

This is where it gets so hot planets lose their surface water and become inhabitable – a scenario thought to have occurred on Venus.

What’s more, the study showed dust can obscure the presence of key biomarkers such as water vapour, methane and oxygen.

The findings will also boost efforts to discover alien microbes and more complex forms of life, by narrowing down the best places to look and opens up a wider habitable zone. Stock image

The findings will also boost efforts to discover alien microbes and more complex forms of life, by narrowing down the best places to look and opens up a wider habitable zone. Stock image

‘This should be taken into consideration when interpreting observations about the habitability of exoplanets,’ said Boutle.

The presence of mineral dust is known to play a substantial role in climate – both regionally on Earth and globally on Mars.

Co author Professor Manoj Joshi, of the University of East Anglia, said the possibility of exoplanets supporting life depends on the atmospheric make-up as well as the amount of light from its star. 

‘Airborne dust is something that might keep planets habitable, but also obscures our ability to find signs of life on these planets,’ he said.

‘These effects need to be considered in future research.’

The quest to identify habitable planets far beyond our solar system is an integral part of current and future space missions.

Many missions are focused on answering the question of whether we are alone.

Latest calculations suggest there could be two trillion galaxies in the universe. The Milky Way alone has at least 100 billion alien planets, and possibly many more.     

Research has been published in the journal Nature Communications.

Scientists study the atmosphere of distant exoplanets using enormous space satellites like Hubble

Distant stars and their orbiting planets often have conditions unlike anything we see in our atmosphere. 

To understand these new world’s, and what they are made of, scientists need to be able to detect what their atmospheres consist of.  

They often do this by using a telescope similar to Nasa’s Hubble Telescope.

These enormous satellites scan the sky and lock on to exoplanets that Nasa think may be of interest. 

Here, the sensors on board perform different forms of analysis. 

One of the most important and useful is called absorption spectroscopy. 

This form of analysis measures the light that is coming out of a planet’s atmosphere. 

Every gas absorbs a slightly different wavelength of light, and when this happens a black line appears on a complete spectrum. 

These lines correspond to a very specific molecule, which indicates it’s presence on the planet. 

They are often called Fraunhofer lines after the German astronomer and physicist that first discovered them in 1814.

By combining all the different wavelengths of lights, scientists can determine all the chemicals that make up the atmosphere of a planet. 

The key is that what is missing, provides the clues to find out what is present.  

It is vitally important that this is done by space telescopes, as the atmosphere of Earth would then interfere. 

Absorption from chemicals in our atmosphere would skew the sample, which is why it is important to study the light before it has had chance to reach Earth. 

This is often used to look for helium, sodium and even oxygen in alien atmospheres.  

This diagram shows how light passing from a star and through the atmosphere of an exoplanet produces Fraunhofer lines indicating the presence of key compounds such as sodium or helium 

This diagram shows how light passing from a star and through the atmosphere of an exoplanet produces Fraunhofer lines indicating the presence of key compounds such as sodium or helium