Astronomers have spotted dozens of rogue planets floating free from their stars after turning the Euclid space telescope to look at a distant region of the Milky Way.
The wandering worlds were seen deep inside the Orion nebula, a giant cloud of dust and gas 1,500 light years away, and described in the first scientific results announced by Euclid 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 is made up of dark matter, an invisible substance that clings around galaxies and behaves like a cosmic glue, and dark energy, which is said to drive the accelerating expansion of the universe.
The first wave of scientific results come from only 24 hours of observations, which revealed 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.
A flurry of new images from the same observations are the largest ever taken in space and demonstrate the stunning wide-field views that astronomers can expect from Euclid in the coming years. Among those released on Thursday is a breathtaking image of Messier 78, a vibrant star nursery shrouded in interstellar dust, that reveals complex filaments of gas and dust in unprecedented detail.
“I’ve been absolutely amazed at the images I’ve seen,” said Prof Mark Cropper, the lead scientist on Euclid’s VIS camera at UCL. “These are not just pretty pictures, these images 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 as much mass as 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 within 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, curving tidal tails.
The rogue planets spotted by Euclid are about 3m years old, making them youngsters on the cosmic scale. They are at least four times as big as Jupiter and were detected thanks to the warmth they emit. Astronomers know they are free-floating because they are so far away 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’ve taken a few observations and seen these planets means that if we go deeper and look over larger areas, which we will, we’ll see a plethora 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 turf them out of early solar systems. “This is just the very early days, there’s a lot more to be done,” Conselice added. “It’s a great time to be working on Euclid and in astronomy in general.”
