Monday, April 15, 2024

WORLD | 13-07-2022 14:38

NASA telescope reveals never-before-seen details, heralding new era of astronomy

From its celestial perch almost one million miles from Earth, the James Webb Space Telescope is giving humanity its deepest look ever into the farthest reaches of the universe.

The cosmic cliffs of a stellar nursery and a quintet of galaxies bound in a celestial dance: NASA released the next wave of images from the James Webb Space Telescope this week, heralding a new era of astronomy.

"Every image is a new discovery," said NASA administrator Bill Nelson. "Each will give humanity a view of the universe that we've never seen before."

Released in a drip feed from the Goddard Space Flight Center, the new images demonstrated the full power of the US$10-billion observatory, which uses infrared cameras to gaze into the distant universe with unprecedented clarity.

"They're beautiful and they're full of wonderful discoveries and science, and lots of things we haven't identified are in there," said Nobel-winning cosmologist and Webb senior project scientist John Mather, reacting to the images.

On Monday, Webb revealed the sharpest image to date of the early universe, teeming with thousands of galaxies going back more than 13 billion years.

The latest tranche included the "mountains" and "valleys" of a star-forming region called NGC 3324 in the Carina Nebula, dubbed the "Cosmic Cliffs," 7,600 light years away.

"For the first time we're seeing brand new stars that were previously completely hidden from our view," said NASA astrophysicist Amber Straughn.

Scientists expect a torrent of knowledge from the telescope, which scans infrared frequencies that aren’t visible to the human eye, but are rich in information about the building blocks of the universe.

“I’m very excited,” said Christopher Johns-Krull, a professor of physics and astronomy at Rice University in Houston who studies planets outside Earth’s solar system. “The James Webb is going to reveal a lot, and truly move the field forward.” 

The telescope “is going to be particularly powerful for looking at planets around other stars,” he said. Possibilities include finding a planet that supports life, and knowledge about how galaxies are formed.


Stellar nurseries and graveyards

Webb also revealed never-before-seen details of Stephan's Quintet, a grouping of five galaxies including four that experience repeated close encounters, which provide insights into how early galaxies formed at the start of the universe.

At the centre of the cluster is a black hole called an active galactic nucleus, "which means stuff is flowing in, it gets cooked to high temperatures, and some of it gets spit back out again," explained Mather.

Studying the black hole will allow scientists to better understand the one at the centre of our own Milky Way, called Sagittarius A*.

A dim star at the centre of the Southern Ring Nebula was found for the first time to be cloaked in dust, as it spews out rings of gas and dust in its death throes.

Understanding the molecules present in such stellar graveyards can help scientists learn more about the process of stellar death. 

The telescope also detailed water vapour in the atmosphere of a faraway giant gas planet. 

The spectroscopy – an analysis of light that reveals detailed information – was of planet WASP-96 b, which was discovered in 2014.

Scientists will next hope to train the spectrographic instruments on small rocky worlds such as our own, to search for signs of habitability.

Fundamental discoveries expected

Webb's first images have set the space community alight, and were shown this week on giant screens in New York City's Times Square and in London.

Launched in December 2021 from French Guiana on an Ariane 5 rocket, Webb is orbiting the Sun at a distance of a million miles (1.6 million kilometres) from Earth, in a region of space called the second Lagrange point. It remains in a fixed position relative to the Earth and Sun, with minimal fuel required for course corrections and manoeuvring its instruments.

A wonder of engineering, Webb is one of the most expensive scientific platforms to date, comparable to the Large Hadron Collider at CERN, and also among the most complex machines ever built. Its primary mirror is over 21 feet (6.5 metres) wide and is made up of 18 gold-coated mirror segments. Like a camera held in one's hand, the structure has to remain very still for the best shots, with Webb's engineers minimising its wobble to just 17 millionths of a millimetre.

After the first images, astronomers around the globe will get shares of time on the telescope, with projects selected competitively through a process in which applicants and selectors don't know each other's identities, to minimise bias.

Thanks to an efficient launch, NASA estimates Webb has enough propellant for a 20-year life, as it works in concert with the Hubble and Spitzer space telescopes to answer fundamental questions about the cosmos – including those scientists don't yet know to ask.

Hubble played a key role in discovering that dark energy is causing the universe to expand at an ever-growing rate, "so it's hard to imagine what we might learn with this 100 times more powerful instrument."

More to come

The James Webb Space Telescope's first images aren't just breathtaking – they contain a wealth of scientific insights and clues that researchers are eager to pursue. Its first image, released Monday, delivered the deepest and sharpest infrared image of the distant universe so far, "Webb's First Deep Field." The white circles and ellipses are from the galaxy cluster in the foreground called SMACS 0723, as it appeared more than 4.6 billion years ago – roughly when our Sun formed too. The reddish arcs are from light from ancient galaxies that has travelled more than 13 billion years, bending around the foreground cluster, which acts as a gravitational lens. The composite image, which required a 12.5 hour exposure time, is considered a practice run. Given longer exposure time, Webb should break all-time distance records by gazing back to the first few hundred million years after the Big Bang, 13.8 billion years ago. 


related news


More in (in spanish)