Science
10 times Webb telescope blew us away with images of universe
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It is no exaggeration to say the James Webb Space Telescope (JWST) represents a new era for modern astronomy.
Launched on December 25 last year and fully operational since July, the telescope offers glimpses of the universe that were inaccessible to us before. Like the Hubble Space Telescope, the JWST is in space, so it can take pictures with stunning detail free from the distortions of Earth’s atmosphere.
However, while Hubble is in orbit around Earth at an altitude of 540km, the JWST is 1.5 million kilometres distant, far beyond the Moon. From this position, away from the interference of our planet’s reflected heat, it can collect light from across the universe far into the infrared portion of the electromagnetic spectrum.
This ability, when combined with the JWST’s larger mirror, state-of-the-art detectors, and many other technological advances, allows astronomers to look back to the universe’s earliest epochs.
As the universe expands, it stretches the wavelength of light travelling towards us, making more distant objects appear redder. At great enough distances, the light from a galaxy is shifted entirely out of the visible part of the electromagnetic spectrum to the infrared. The JWST is able to probe such sources of light right back to the earliest times, nearly 14 billion years ago.
The Hubble telescope continues to be a great scientific instrument and can see at optical wavelengths where the JWST cannot. But the Webb telescope can see much further into the infrared with greater sensitivity and sharpness.
Let’s have a look at ten images that have demonstrated the staggering power of this new window to the universe.
1. Mirror alignment complete
Despite years of testing on the ground, an observatory as complex as the JWST required extensive configuration and testing once deployed in the cold and dark of space.
One of the biggest tasks was getting the 18 hexagonal mirror segments unfolded and aligned to within a fraction of a wavelength of light. In March, NASA released the first image (centred on a star) from the fully aligned mirror. Although it was just a calibration image, astronomers immediately compared it to existing images of that patch of sky – with considerable excitement.
2. Spitzer vs MIRI
This early image, taken while all the cameras were being focused, clearly demonstrates the step change in data quality that JWST brings over its predecessors.
On the left is an image from the Spitzer telescope, a space-based infrared observatory with an 85cm mirror; the right, the same field from JWST’s mid-infrared MIRI camera and 6.5m mirror. The resolution and ability to detect much fainter sources is on show here, with hundreds of galaxies visible that were lost in the noise of the Spitzer image. This is what a bigger mirror situated out in the deepest, coldest dark can do.
3. The first galaxy cluster image
The galaxy cluster with the prosaic name of SMACS J0723.3–7327 was a good choice for the first colour images released to the public from the JWST.
The field is crowded with galaxies of all shapes and colours. The combined mass of this enormous galaxy cluster, over 4 billion light years away, bends space in such a way that light from distant sources in the background is stretched and magnified, an effect known as gravitational lensing.
These distorted background galaxies can be clearly seen as lines and arcs throughout this image. The field is already spectacular in Hubble images (left), but the JWST near-infrared image (right) reveals a wealth of extra detail, including hundreds of distant galaxies too faint or too red to be detected by its predecessor.
4. Stephan’s Quintet
These images depict a spectacular group of galaxies known as Stephan’s Quintet, a group that has long been of interest to astronomers studying the way colliding galaxies interact with one another gravitationally.
On the left we see the Hubble view, and the right the JWST mid-infrared view. The inset shows the power of the new telescope, with a zoom in on a small background galaxy. In the Hubble image we see some bright star-forming regions, but only with the JWST does the full structure of this and surrounding galaxies reveal itself.
5. The Pillars of Creation
The so-called Pillars of Creation is one of the most famous images in all of astronomy, taken by Hubble in 1995. It demonstrated the extraordinary reach of a space-based telescope.
It depicts a star-forming region in the Eagle Nebula, where interstellar gas and dust provide the backdrop to a stellar nursery teeming with new stars. The image on the right, taken with the JWST’s near-infrared camera (NIRCam), demonstrates a further advantage of infrared astronomy: the ability to peer through the shroud of dust and see what lies within and behind.
6. The ‘Hourglass’ Protostar
This image depicts another act of galactic creation within the Milky Way. This hourglass-shaped structure is a cloud of dust and gas surrounding a star in the act of formation – a protostar called L1527.
Only visible in the infrared, an “accretion disk” of material falling in (the black band in the centre) will eventually enable the protostar to gather enough mass to start fusing hydrogen, and a new star will be born.
In the meantime, light from the still-forming star illuminates the gas above and below the disk, making the hourglass shape. Our previous view of this came from Spitzer; the amount of detail is once again an enormous leap ahead.
7. Jupiter in infrared
The Webb telescope’s mission includes imaging the most distant galaxies from the beginning of the universe, but it can look a little closer to home as well.
Although JWST cannot look at Earth or the inner Solar System planets – as it must always face away from the Sun – it can look outward at the more distant parts of our Solar System. This near-infrared image of Jupiter is a beautiful example, as we gaze deep into the structure of the gas giant’s clouds and storms. The glow of auroras at both the northern and southern poles is haunting.
This image was extremely difficult to achieve due to the fast motion of Jupiter across the sky relative to the stars and because of its fast rotation. The success proved the Webb telescope’s ability to track difficult astronomical targets extremely well.
8. The Phantom Galaxy
These images of the so-called Phantom Galaxy or M74 reveal the power of JWST not only as the latest and greatest of astronomical instruments, but as a valuable complement to other great tools. The middle panel here combines visible light from Hubble with infrared from Webb, allowing us to see how starlight (via Hubble) and gas and dust (via JWST) together shape this remarkable galaxy.
Much JWST science is designed to be combined with Hubble’s optical views and other imaging to leverage this principle.
9. A super-distant galaxy
Although this galaxy – the small, red blob in the right image – is not among the most spectacularly picturesque our universe has to offer, it is just as interesting scientifically.
This snapshot is from when the universe was a mere 350 million years old, making this among the very first galaxies ever to have formed. Understanding the details of how such galaxies grow and merge to create galaxies like our own Milky Way 13 billion years later is a key question, and one with many remaining mysteries, making discoveries like this highly sought after.
It is also a view only the JWST can achieve. Astronomers did not know quite what to expect; an image of this galaxy taken with Hubble would appear blank, as the light of the galaxy is stretched far into the infrared by the expansion of the universe.
10. This giant mosaic of Abell 2744
This image (click here for full view) is a mosaic (many individual images stitched together) centred on the giant Abell 2744 galaxy cluster, colloquially known as “Pandora’s Cluster”. The sheer number and variety of sources that the JWST can detect is mind boggling; with the exception of a handful of foreground stars, every spot of light represents an entire galaxy.
In a patch of dark sky no larger than a fraction of the full Moon there are umpteen thousands of galaxies, really bringing home the sheer scale of the universe we inhabit. Professional and amateur astronomers alike can spend hours scouring this image for oddities and mysteries.
Over the coming years, JWST’s ability to look so deep and far back into the universe will allow us to answer many questions about how we came to be. Just as exciting are the discoveries and questions we can not yet foresee. When you peel back the veil of time as only this new telescope can, these unknown unknowns are certain to be fascinating.
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An asteroid the size of a delivery truck will whip past Earth on Thursday night, one of the closest such encounters ever recorded.
NASA insists it will be a near miss with no chance of the asteroid hitting Earth.
The U.S. space agency said Wednesday that this newly discovered asteroid will zoom 3,600 kilometres above the southern tip of South America. That’s 10 times closer than the bevy of communication satellites circling overhead.
The closest approach will occur at 7:27 p.m. ET.
Even if the space rock came a lot closer, scientists said most of it would burn up in the atmosphere, with some of the bigger pieces possibly falling as meteorites.
NASA’s impact hazard assessment system, called Scout, quickly ruled out a strike, said its developer, Davide Farnocchia, an engineer at the agency’s Jet Propulsion Laboratory in Pasadena, Calif.
“But despite the very few observations, it was nonetheless able to predict that the asteroid would make an extraordinarily close approach with Earth,” Farnocchia said in a statement.
“In fact, this is one of the closest approaches by a known near-Earth object ever recorded.”
Asteroid spotted by amateur astronomer in Crimea
Discovered Saturday, the asteroid known as 2023 BU is believed to be 3.5 to 8.5 metres across.
It was first spotted by Gennady Borisov, the same amateur astronomer in Crimea who discovered an interstellar comet in 2019.
Within a few days, dozens of observations were made by astronomers around the world, allowing them to refine the asteroid’s orbit.
The asteroid’s path will be drastically altered by Earth’s gravity once it zips by. Instead of circling the sun every 359 days, it will move into an oval orbit lasting 425 days, according to NASA.
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WASHINGTON –
The United States plans to test a spacecraft engine powered by nuclear fission by 2027 as part of a long-term NASA effort to demonstrate more efficient methods of propelling astronauts to Mars in the future, the space agency’s chief said on Tuesday.
NASA will partner with the U.S. military’s research and development agency, DARPA, to develop a nuclear thermal propulsion engine and launch it to space “as soon as 2027,” NASA administrator Bill Nelson said during a conference in National Harbor, Maryland.
The U.S. space agency has studied for decades the concept of nuclear thermal propulsion, which introduces heat from a nuclear fission reactor to a hydrogen propellant in order to provide a thrust believed to be far more efficient than traditional chemical-based rocket engines.
NASA officials view nuclear thermal propulsion as crucial for sending humans beyond the moon and deeper into space. A trip to Mars from Earth using the technology could take roughly four months instead of some nine months with a conventional, chemically powered engine, engineers say.
That would substantially reduce the time astronauts would be exposed to deep-space radiation and would also require fewer supplies, such as food and other cargo, during a trip to Mars.
“If we have swifter trips for humans, they are safer trips,” NASA deputy administrator and former astronaut Pam Melroy said Tuesday.
The planned 2027 demonstration, part of an existing DARPA research program that NASA is now joining, could also inform the ambitions of the U.S. Space Force, which has envisioned deploying nuclear reactor-powered spacecraft capable of moving other satellites orbiting near the moon, DARPA and NASA officials said.
DARPA in 2021 awarded funds to General Atomics, Lockheed Martin and Jeff Bezos’ space company Blue Origin to study designs of nuclear reactors and spacecraft. By around March, the agency will pick a company to build the nuclear spacecraft for the 2027 demonstration, the program’s manager Tabitha Dodson said in an interview.
The joint NASA-DARPA effort’s budget is US$110 million for fiscal year 2023 and is expected to be hundreds of millions of dollars more through 2027.
Reporting by Joey Roulette; Editing by Chizu Nomiyama and David Gregorio
Science
The green comet ZTF returns to the solar system 50,000 years later… and it will be visible from Earth
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For astronomy enthusiasts, February 1 is marked in red on their calendars. The reason: it is not every day that there is a chance to see a green comet.
In fact, it is the first time in 50,000 years that C/2022 ZTF will return to the solar system. And it will be early next month when it will reach its closest position to Earth.
Specifically, the green comet ZTF will pass 42 million light years from our planet. Experts are not 100 percent sure whether it will be visible from the surface without the use of any instrument. However, if we have specific astronomy binoculars or telescopes, we will be able to see it without any problem.
As usually happens in these cases, the best places to observe the comet, this one or any other, are places with little artificial light. That is to say, we should move away from urban centres and it is preferable to do so in the hours before dawn.
Why is comet ZTF green?
Comet ZTF has a brightness and a colour that, although not unique, is clearly distinctive. Its hue is due to the fact that it is composed, among other materials, of diatomic carbon.
When it comes into contact with sunlight, the decomposition of this element causes the gas to acquire this spectacular colour.
Comet ZTF was discovered in March 2022
Frank Masci and Bryce Bolin of the Palomar Observatory in California were responsible for spotting the striking comet ZTF in the sky. It is so named because its discovery is part of the Zwicky Transient Facility surveillance programme, which uses the powerful Schmidt telescope at the facility.
Initially, the scientists responsible for the discovery thought it was an asteroid, but they quickly realised that this was not the case. Despite the striking colour of this comet, experts advise keeping expectations low. In any case, it is an event that has aroused great interest in the community.
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