Astronomers have seen dozens of rogue planets drifting free from their stars after passing the Euclid Space Telescope to look at a distant region of the Milky Way.
The wandering worlds were spotted deep within the Orion Nebula, a giant cloud of dust and gas 1,500 light-years away, and described in the first scientific results announced by Euclidean mission researchers.
The European Space Agency (Esa) launched the €1bn (£851m) observatory last summer on a six-year mission to create a 3D map of the cosmos. Armed with its images, scientists hope to understand more about the mysterious 95% of the universe that is unexplained.
According to astronomers’ theories, most of the universe consists of dark matter, an invisible substance that clings to galaxies and acts like a cosmic glue, and dark energy, which is said to drive the accelerating expansion of the universe.
The first wave of science results comes from just 24 hours of observations, revealing 11m objects in visible light and 5m in infrared. Along with the rogue planets, the researchers describe new star clusters, dwarf galaxies and very distant, bright galaxies from the first billion years of the universe.
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A wave of new images from the same observations are the largest ever taken in space and demonstrate the stunning wide-field views astronomers can expect from Euclid in the coming years. Among those released Thursday is a stunning image of Messier 78, a vibrant star nursery shrouded in interstellar dust, revealing complex filaments of gas and dust in unprecedented detail.
“I was absolutely amazed by the images I saw,” says Prof Mark Cropper, the lead scientist on Euclid’s VIS camera at UCL. “These are not just pretty pictures, these pictures are packed with new information.”
One of the newly released images shows Abell 2390, a giant conglomeration of more than 50,000 Milky Way-like galaxies. Such galaxy clusters contain up to 10 trillion times the mass of the sun, much of which is believed to be elusive dark matter. Another image of the Abell 2764 galaxy cluster reveals hundreds of galaxies orbiting in a halo of dark matter.
Other images capture NGC 6744, one of the largest spiral galaxies in the nearby Universe, and the Dorado Group of galaxies, where evolving and merging galaxies produce shell-like structures and vast, curved tyres.
The rogue planets spotted by Euclid are about 3m years old, making them youngsters on the cosmic scale. They are at least four times the size of Jupiter and were detected thanks to the warmth they emit. Astronomers know they are free-floating because they are so far from the nearest stars. The celestial strays are destined to drift through the galaxy unless they encounter a star that pulls them into orbit.
“The fact that we took some observations and saw these planets means that if we go deeper and look over larger areas, which we will, we will see an abundance of planets and learn a lot more about planet formation,” said Christopher Conselice, professor of extragalactic astronomy at the University of Manchester.
Rogue planets have been found before, but not on this scale. By studying them in numbers, astronomers hope to gain a clearer understanding of the mechanisms that can remove them from early solar systems. “It’s just the very early days, there’s a lot more to do,” Conselice added. “It’s a good time to be working on Euclid and in astronomy in general.”
