The wait is over. The first scientific image from NASA’s James Webb Space
Telescope has dropped, and astronomers are mesmerized. US President Joe
Biden released the historic picture, which is the deepest astronomical image
of the distant Universe, during a press conference at the White House on
Monday. NASA will publish more images on 12 July.
The first image, closely guarded before the reveal, showcases the
telescope’s transformational capabilities. It shows thousands of distant
galaxies in the constellation Volans, fainter than any galaxies seen before,
in a patch of sky no larger than that covered by a grain of sand held at
arm’s length.
It shows “the oldest documented light in the history of the Universe, from
over 13 billion — let me say that again — 13 billion years ago”, said Biden
when releasing the image. “It’s hard to even fathom.”
“I’m just amazed,” says Vivian U, an astronomer at the University of
California, Irvine. “I’m just panning through the image, figuring out what
all the smudges are and why they’re there.”
Scientists expect Webb, the largest telescope ever launched into space, to
revolutionize the study of the cosmos. The first batch of images to be
released, including the deep-field shot, has been selected to encompass all
of the observatory’s major scientific targets: the early Universe, the
evolution of galaxies and stars, and planets beyond the Solar System.
A transformational telescope
Unlike the Hubble Space Telescope — one of the largest and most famous space
telescopes — Webb detects mainly infrared wavelengths. By studying infrared
light, it can penetrate the clouds of dust that obscure newborn stars and
can peer farther into the cosmos than ever before. Webb “is not Hubble
version 2 — it’s really a very different telescope”, says Zolt Levay, a
retired astronomer and image processor who worked for decades on Hubble
imagery. “It’s invisible light that we’re looking at.”
Galaxies that lie very far from Earth can be seen only in infrared
wavelengths, because the expansion of the Universe has shifted their light
out of the visible part of the electromagnetic spectrum and into the
infrared. Webb’s first deep-field image shows this effect dramatically
around a cluster of galaxies known as SMACS 0723, which lies around 4
billion light-years from Earth. The clusters’ gravity bends and magnifies
the light of objects behind it, allowing astronomers to glimpse extremely
distant objects.
“The things that are catching my eye are the distorted galaxies,” says Lisa
Dang, an astronomer at McGill University in Montreal, Canada. “They look
like no other galaxies that we know of.”
Webb’s first image shows galaxies that might date back more than 13 billion
years, nearly all of the way to the Big Bang that created the Universe 13.8
billion years ago. It calls to mind several iconic deep-field images taken
by Hubble. The first of those, made over the course of 10 days during the
Christmas holidays in 1995, revealed that a seemingly empty patch of sky was
dotted with thousands of previously unseen galaxies. Webb’s first image took
just 12.5 hours to compile, compared with the weeks it took Hubble to
observe other deep fields.
Webb also specializes in spectroscopy, the study of how light at various
wavelengths interacts with matter. The infrared spectra of astronomical
objects that Webb will produce can reveal what the objects are made of
chemically — to a degree that images cannot. “That’s where some of the
really exciting science will happen,” says Elizabeth Kessler, a historian at
Stanford University in California who has studied the aesthetic impact of
Hubble imagery.
Webb’s first scientific images come as something of a catharsis for the
telescope project, which has suffered from years of delays and billions of
dollars in cost overruns. Initially envisioned in 1989, Webb ultimately cost
NASA nearly US$10 billion. It is the most complex space observatory ever
built. Its 6.5-metre-wide primary mirror had to launch folded up, and then
open like a butterfly spreading its wings, through a series of
anxiety-inducing manoeuvres. Engineers had to test its tennis-court-sized
sunshield — made of gossamer-thin layers of aluminium-coated polymer film —
multiple times to be sure that it would unfurl properly and then protect the
telescope’s instruments in the deep freeze of outer space.
NASA’s partners, the European and Canadian space agencies, contributed
approximately another $1 billion in total to make the telescope a reality.
Webb ultimately launched in December 2021 and spent six months readying its
instruments for science; it is expected to operate for at least 20 years.
The world is watching
Webb is named after James E. Webb, who ran NASA during the height of the
Apollo Moon-exploration programme in the 1960s. Some astronomers have called
for the telescope to be renamed, given that James Webb held a prominent
leadership role at the US State Department in the late 1940s and early
1950s, when the department was at the forefront of the US government’s
effort to identify and fire gay and lesbian employees. NASA has said that it
has no evidence to warrant changing the telescope’s name. Its acting chief
historian, along with another historian, continue to research the issue and
are expected to release a report on their findings soon.
The first images from Webb represent only a sliver of the science it will
make possible. They were taken over just 120 hours of observation during the
past few weeks. Upcoming studies include explorations of the planets Jupiter
and Saturn, of small faint stars known as red dwarfs, of distant galaxies
that are colliding with one another and of hot rocky planets around other
stars. U, who has observing time on Webb, is already anticipating getting
her first data from the telescope on Thursday. That’s when the Webb team
will upload observations of galaxy mergers to a website for her and her
colleagues to access.
Levay remembers working on some of Hubble’s most iconic image releases, such
as the publication of pictures taken after astronauts visited the
Earth-orbiting telescope to upgrade its instruments. “You know the whole
world’s watching, and that you’d better deliver,” he says.
Webb seems to have done just that. “It’s working better than I think anybody
expected,” Levay says. “And that’s great.”
Source: Link
Tags:
Space & Astrophysics