First image from James Webb telescope shows most distant galaxies
Infant galaxies forming in the young universe more than 13bn years ago enraptured viewers when Nasa released the first image from the James Webb Space Telescope on Monday night.
The picture shows a galaxy cluster called SMACS 0723 as it appeared 4.6bn years ago — about the time when the Earth formed — acting as a gravitational lens and magnifying the far more distant and older galaxies that appear behind it.
Bill Nelson, Nasa administrator, revealed the image at a White House briefing with President Joe Biden and Vice-president Kamala Harris. He said the oldest galaxies in the picture might date back to within 300mn years of the birth of the universe 13.8bn years ago.
The “deep field” image covers a patch of sky about the size of a grain of sand held at arm’s length by someone on the ground, Nelson said. It is a composite made from images at different infrared wavelengths over a period of 12 hours.
Nasa and its partner, the European Space Agency, will release four more early scientific observations from the $10bn telescope on Tuesday.
One will include an analysis of a planet orbiting a distant star. The spectrum of the giant gas planet Wasp-96b, orbiting a star 1,150 light years away, will indicate the chemical composition of its atmosphere.
Astronomers hope that this technique will eventually show which planets are likely to host life — for example through the presence of methane, oxygen and organic molecules — though the discovery of another inhabited world is not expected in the near future.
The three other observations will show: Carina Nebula, a “stellar nursery” 7,600 light years away; Southern Ring Nebula, a giant expanding gas cloud 2,000 light years away; and Stephan’s Quintet, a compact group of five galaxies 290mn light years from Earth.
“These scientific images come from five days observing,” said Mark McCaughrean, Esa’s senior science adviser. “Think of what’s to come in the months and years ahead.”
This week’s Webb pictures are not the first seen by the public — Nasa released a few “engineering images” last month from the telescope’s commissioning period — but they are the first full-colour scientific images.
Webb’s images have false colour added to show the wavelengths observed because they are recorded in the infrared region, beyond the range of human eyes. In contrast the Hubble Space Telescope, still working after 32 years in orbit, observes visible light.
After three decades of design and construction, plagued by delays and cost overruns, Webb had a perfect launch on an Ariane 5 rocket on Christmas Day last year.
The launcher directed Webb so precisely in the right direction to its destination, the “second Lagrange point” 1.5mn km from Earth, that the spacecraft had to use less fuel than expected for final positioning, said Richard Ellis, astrophysics professor at University College London, who has been involved in the project from its early years. It therefore has more fuel left to keep itself in place during the mission.
“The launch precision has extended the expected life of the telescope,” he said. “The original specification was five years with a goal of 10. Now Webb can easily achieve 10 years and might go on for 15.”