Jonathan Amos* says the pioneering James Webb Space Telescope has detected a strange dust storm on a planet 40 light years from Earth.
A raging dust storm has been observed on a planet outside our Solar System for the first time.
It was detected on the exoplanet known as VHS 1256b (artist’s impression pictured), which is about 40 light years from Earth.
It took the remarkable capabilities of the new James Webb Space Telescope (JWST) to make the discovery.
The dust particles are silicates — small grains comprising silicon and oxygen, which form the basis of most rocky minerals.
However, the storm detected by the JWST isn’t quite the same phenomenon you would get in an arid, desert region on our planet. It’s more of a rocky mist.
Beth Biller, from the University of Edinburgh and the Royal Observatory, Edinburgh, United Kingdom said the storm consisted of particles much finer than sand grains.
“We’re talking silicate grains the size of smoke particles,” Professor Biller said.
“That’s what the clouds on VHS 1256b would be like, but a lot hotter. This planet is a hot, young object. The cloud-top temperature is maybe similar to the temperature of a candle flame.”
VHS 1256b was first identified by the UK-developed Vista telescope in Chile in 2015.
It’s what’s termed a ‘super Jupiter’ — a planet similar to the gas giant in our own Solar System, but a lot bigger with perhaps 12-to-18 times the mass.
It circles a couple of stars at great distance — about four times the distance that Pluto is from our Sun.
Earlier observations of VHS 1256b showed it to be red-looking, hinting that it might have dust in its atmosphere. The JWST study confirmed it.
“It’s fascinating because it illustrates how different clouds on another planet can be from the water vapour clouds we are familiar with on Earth,” Professor Biller said.
“We see carbon monoxide (CO) and methane in the atmosphere of VHS 1256b, which is indicative of it being hot and turbulent, with material being drawn up from deep.”
She said there were probably multiple layers of silicate grains.
“The ones that we’re seeing are some of the very, very fine grains that are higher up in the atmosphere, but there may be bigger grains deeper down in the atmosphere,” Professor Biller said.
Telescopes have previously detected silicates in so-called brown dwarfs. These are essentially star-like objects that have failed to ignite properly, but this is a first for a planet-sized object.
To make the detection, the JWST used its Mid-Infrared Instrument (Miri), and its Near-Infrared Spectrometer (NirSpec).
They didn’t take pretty pictures of the planet, at least not in this instance.
What they did was tease apart the light coming from VHS 1256b into its component colours as a way to discern the composition of the atmosphere.
Miri Co-Principal Investigator, Gillian Wright said the JWST was the only telescope that could measure all these molecular and dust features together.
“The dynamic picture of the atmosphere of VHS 1256b provided by this study is a prime example of the discoveries enabled by using the advanced capabilities of Miri and NirSpec together,” Professor Wright said.
The JWST’s primary mission is to observe the pioneer stars and galaxies that first shone just a few hundred million years after the Big Bang.
However, a key objective is to investigate exoplanets. In Miri and NirSpec it has the tools to study their atmospheres in unprecedented detail.
Scientists hope they might even be able to tell whether some exoplanets have conditions suitable to host life.
The JWST is a collaborative project of the United States, European and Canadian Space Agencies.
It was launched in December 2021 and is regarded as the successor to the Hubble Space Telescope.
*Jonathan Amos has been Science Correspondent with the British Broadcasting Corporation since 1994. His online reporting focuses on the Earth sciences, with a particular interest in the changes taking place in polar regions. He can be contacted @BBCAmos.
This article first appeared on the BBC website.
