The search for other places in the universe that could harbour life has so far discovered more than 6,000 alien planets, but most of these have been hellish worlds rather than Earth-like oases.

Astronomers are now able to use the James Webb space telescope (JWST) to examine the rocky surfaces of planets in orbit around distant stars and have seized a “unique” opportunity to examine a “super-Earth” and find out what its crust is made of.

What they have discovered, however, is not somewhere likely to feature in any tourism brochures of the future as an idyllic interstellar holiday spot.

Instead, it is a “hot, barren rock” that resembles a giant version of the planet Mercury, hurtling around its host star once every 11 hours. But the finding is the “next step” in being able to examine alien planets in greater detail, aiding the search for habitable worlds.

The JWST has provided breathtaking detail about the atmospheres of “exoplanets”, studying the chemical make-up of their clouds by detecting small changes in the starlight that passes through them.

It is now being used to analyse radiation being emitted as heat by the planets, revealing unprecedented details about their surfaces.

A study, published in the journal Nature Astronomy, has documented a planet known as LHS 3844 b, in orbit around a red dwarf star, the most common type of star in our galaxy. It is classed as a “super-Earth” because it is about 30 per cent larger than Earth.

“Thanks to the amazing sensitivity of JWST, we can detect light coming directly from the surface of this distant rocky planet,” said Laura Kreidberg of the Max Planck Institute for Astronomy.

“We see a dark, hot, barren rock, devoid of any atmosphere.”

The study did not expect to find a habitable world on LHS 3844 b, however.

Instead, astronomers used the absence of an atmosphere to give them a clearer glimpse of the planet’s surface so they could detect heat being emitted in the form of infrared radiation.

The study noted the ability to describe the rocky surface of an exoplanet still eluded scientists. It said: “Different types of rock have distinct spectral features that are diagnostic of the chemical composition and other physical properties like surface texture. Measurements of these features can provide valuable clues about a planet’s geologic history and interior processes.”

LHS 3844 b is 48.5 light years from our sun. That is 285 trillion miles, or about 100,000 times farther from our sun than Neptune. This makes it a relatively near neighbour in cosmic terms, but it would still take a spacecraft 1.3 million years to reach if travelling at the top speed of last month’s Artemis II mission to the moon.

The planet is hot enough to release a detectable infrared signal, but not so hot as to be a molten world, offering a “unique opportunity” to study it. Astronomers could tell from the radiation that it does not have a silicate-rich crust like Earth, showing that it is unlikely to have had water or shifting tectonic plates. Instead, it is likely to be made mainly of basalt.

The readings suggest it has a powdery surface “like the Moon and Mercury”, caused by “space-weathering” as it is struck by radiation.

Researchers said: “This kind of deciphering [of] the geological properties of planets orbiting distant stars is the next step in unveiling their nature.”