Stunning James Webb image shows the heart of our Milky Way | Digital Trends
A new image from the James Webb Space Telescope shows the heart of our galaxy, in a region close to the supermassive black hole at the center of the Milky Way, Sagittarius A*. The image shows a star-forming region where filaments of dust and gas are clumping together to give birth to new baby stars.
The image was captured using Webb’s NIRCam instrument, a camera that looks in the near-infrared portion of the electromagnetic spectrum with shorter wavelengths shown in blue and cyan and longer wavelengths shown in yellow and red.
The full view of the NASA/ESA/CSA James Webb Space Telescope’s NIRCam (Near-Infrared Camera) instrument reveals a 50 light-years-wide portion of the Milky Way’s dense center. An estimated 500,000 stars shine in this image of the Sagittarius C (Sgr C) region, along with some as-yet-unidentified features.NASA, ESA, CSA, STScI, S. Crowe (UVA)
This region is called Sagittarius C, and is located around 300 light-years away from the supermassive black hole Sagittarius A*. For reference, Earth is located much further away from the galactic center, at a distance of around 26,000 light years from Sagittarius A*.
There are thought to be as many as 500,000 stars in the Sagittarius C region, including many young protostars, some of which will go on to become main-sequence stars like our sun. As stars form, they give off powerful stellar winds which blow away nearby material and prevent more stars from forming very close to them.
These outflows are illuminated in the infrared wavelength, and the cyan-colored patches in the image are created by ionized gas. The young stars give off a great deal of energy, which ionizes the hydrogen gas around them and makes them glow in the infrared.
However, there are actually even more stars in this area than can be seen in the image. The pockets of darkness scattered throughout the image aren’t blank but are dense clouds that are dark in the infrared, including a large dense area in the heart of the region.
There are still some surprises to be found in the image too, with some features that scientists need to study in more depth. “Researchers say they have only begun to dig into the wealth of unprecedented high-resolution data that Webb has provided on this region, and many features bear detailed study,” Webb scientists write. “This includes the rose-colored clouds on the right side of the image, which have never been seen in such detail.”
James Webb snaps an image of the famous Crab Nebula | Digital Trends
Located 6,500 light-years away, the Crab Nebula is famous among astronomers for its elaborate and beautiful structure. A new image from the James Webb Space Telescope shows off the gorgeous nebula as seen in the infrared wavelength, highlighting the filaments of dust that create its cage-like shape.
The nebula is a supernova remnant, the result of a massive star that exploded at the end of its life centuries ago. The supernova was observed on Earth in 1054 CE, and since then astronomers have watched the nebula that resulted from that explosion grow and change.
NASA’s James Webb Space Telescope has gazed at the Crab Nebula in the search for answers about the supernova remnant’s origins. Webb’s NIRCam (Near-Infrared Camera) and MIRI (Mid-Infrared Instrument) have revealed new details in infrared light.NASA, ESA, CSA, STScI, Tea Temim (Princeton University)
The nebula has previously been imaged by other telescopes such as the Hubble Space Telescope which looks primarily in the optical wavelength and, more recently, NASA’s Imaging X-ray Polarimetry Explorer observatory which looks in the X-ray wavelength. These results have been combined into a previous image showing the nebula in optical, infrared, and X-ray.
The new Webb image, however, shows different aspects of the object. Using its NIRCam (Near-Infrared Camera) and MIRI (Mid-Infrared Instrument) instruments, Webb can see the structures of gas filaments, which are shown in red and orange, as well as the regions of dust that appear as the fluffy yellow, white, and green areas. Another aspect picked up in the infrared image is a type of radiation called synchrotron radiation, created by a rotating neutron star with a strong magnetic field, which is shown as the white milky substance in the interior of the nebula.
The nebula is being studied to learn about how it formed from the supernova event, which threw out clouds of material when the star exploded.
“Webb’s sensitivity and spatial resolution allow us to accurately determine the composition of the ejected material, particularly the content of iron and nickel, which may reveal what type of explosion produced the Crab Nebula,” said lead researcher Tea Temim of Princeton University in a statement.
There will be yet more data about the Crab Nebula coming soon, as Hubble has also recently re-imaged the object for the first time since it took its original observations in 1999 and 2000.
Hubble captures a stunning ultraviolet image of Jupiter | Digital Trends
You can now see Jupiter in a whole new way, thanks to a new image from the Hubble Space Telescope. Showing the planet in the ultraviolet wavelength, the image highlights the planet’s Great Red Spot — an enormous storm larger than the width of the entire Earth that has been raging for hundreds of years.
The image was released in celebration of Jupiter reaching opposition, meaning it is directly opposite the sun as viewed from the Earth. That means that if you are a keen stargazer, now is a great time to go and look for Jupiter in the night sky as it will look its biggest and brightest.
NASA’s Hubble Space Telescope reveals an ultraviolet view of Jupiter.NASA, ESA, and M. Wong (University of California – Berkeley); Processing: Gladys Kober (NASA/Catholic University of America)
The Hubble Space Telescope looks mostly in the optical light wavelength, which is the same as the human eye can see. But it also has the ability to go beyond this range, both a little bit into the infrared and, in this case, into the ultraviolet. Looking at different wavelengths allows scientists to see different features of cosmic objects like planets and galaxies.
The James Webb Space Telescope, for example, looks in the infrared to observe extremely distant galaxies that are traveling away from us and, as a result. have light that is shifted into the infrared via a process called redshift. The infrared is also useful for being able to look through clouds of dust.
Looking in the ultraviolet wavelength, on the other hand, is useful for observing objects like very young, very hot stars, or looking at the sparse gas and dust floating between stars, called the interstellar medium.
In this case, the view Hubble has of Jupiter is part of a project to study its turbulent atmosphere, looking particularly at its superstorm, the Great Red Spot. The different wavelengths of ultraviolet light are translated into the visible light spectrum to give this color effect.
“Though the storm appears red to the human eye, in this ultraviolet image, it appears darker because high-altitude haze particles absorb light at these wavelengths,” NASA explains in a statement. “The reddish, wavy polar hazes are absorbing slightly less of this light due to differences in either particle size, composition, or altitude.”
You’ve Never Seen Jupiter Look So Much Like Cotton Candy
You probably know Jupiter, the rotund fifth planet from the Sun, as orange and tan with a big red splotch. But the Hubble Space Telescope recently imaged the gas giant in ultraviolet light, giving the world a very different look.
First Full-Color Images From Webb Space Telescope
At UV wavelengths, Jupiter’s clouds appear in bright pinks, blues, and purple hues. The image is false color, meaning that ultraviolet wavelengths—which the human eye cannot see—were assigned to visual light wavelengths for your viewing pleasure. False color image is a bit of a misnomer, because the images aren’t “fake.” Image processors are just doing the best they can to show you the planet how it could look, in the same way that all the images by the Webb Space Telescope are taken at infrared wavelengths our eyes cannot see.
The planet’s Great Red Spot—a massive storm system in Jupiter’s midriff—appears a deep azure instead of its usual dark red. The spot looks darker because, as explained in a NASA release, haze in the loftier parts of Jupiter’s atmosphere absorb light at ultraviolet wavelengths.
It’s not the first time Jupiter’s gotten a makeover through the eyes of one of NASA’s space observatories. In July 2022, the Webb telescope released its first portraits of the gas giant at infrared wavelengths, in which it appeared bright orange. Those images were taken with Webb’s Near-Infrared Camera, or NIRCam. The following month, Webb images of Jupiter and its luminous auroral regions showed the planet in a bluish-gray light.
The recent image was created from data taken by Hubble to study Jupiter’s superstorms, some particularly intense phenomena on what is already a very turbulent planet. Last month, researchers found a high-speed jet blasting through the Jupiter’s lower stratosphere.
But the ultraviolet image makes Jupiter look serene, like a sunset over calm waters. It puts a particularly surly planet in a new light.
Researchers discover a 320-mph jet stream around Jupiter | Digital Trends
The James Webb Space Telescope might be best known for its study of extremely distant galaxies, but it is also used for research on targets closer to home, like planets within our solar system. Last year, the telescope captured a stunning image of Jupiter as seen in the infrared wavelength, and now scientists who have been working on this data have published some of their findings about the planet — including a brand-new feature that they identified in its atmosphere.
This image of Jupiter from NASA’s James Webb Space Telescope’s NIRCam (Near-Infrared Camera) shows stunning details of the majestic planet in infrared light. In Webb’s images of Jupiter from July 2022, researchers recently discovered a narrow jet stream traveling 320 miles per hour (515 kilometers per hour) sitting over Jupiter’s equator above the main cloud decks.NASA, ESA, CSA, STScI, Ricardo Hueso (UPV), Imke de Pater (UC Berkeley), Thierry Fouchet (Observatory of Paris), Leigh Fletcher (University of Leicester), Michael H. Wong (UC Berkeley), Joseph DePasquale (STScI)
Jupiter’s atmosphere is a dramatic, turbulent place, with epic storms like the famous Great Red Spot, which is a storm stretching over 200 miles wide. But the researchers also identified a new feature there — a high-speed jet stream that is an incredible 3,000 miles wide and located over the planet’s equator. This jet stream is high up in the atmosphere, above the main cloud layer, and was visible in the data taken with Webb’s NIRCam instrument.
“This is something that totally surprised us,” said lead researcher Ricardo Hueso of Spain’s University of the Basque Country in a statement. “What we have always seen as blurred hazes in Jupiter’s atmosphere now appear as crisp features that we can track along with the planet’s fast rotation.”
Webb’s near-infrared instruments are ideal for looking at the upper layers of Jupiter’s atmosphere, and are accurate enough to resolve the blurry haze into clearer details. By tracking the movement of small clouds, the researchers could calculate the speed of the jet stream. That showed the jet stream moves at a speed of 320 mph, or around twice the wind speed of a Category 5 hurricane.
Researchers want to observe the jet stream over the next few years to see if its speed is related to the pattern of winds and temperatures seen in the planet’s stratosphere above the equator.
“It’s amazing to me that, after years of tracking Jupiter’s clouds and winds from numerous observatories, we still have more to learn about Jupiter, and features like this jet can remain hidden from view until these new NIRCam images were taken in 2022,” said team member Leigh Fletcher of England’s University of Leicester.
James Webb captures a stellar nursery in nearby dwarf galaxy | Digital Trends
A gorgeous new image from the James Webb Space Telescope shows a stunning sight from one of our galactic neighbors. The image shows a region of star formation called NGC 346, where new stars are being born. It’s located in the Small Magellanic Cloud, a dwarf galaxy that is a satellite galaxy to the Milky Way.
The star-forming region of the Small Magellanic Cloud (SMC) was previously imaged by the Hubble Space Telescope in 2005, but this new image gives a different view as it is taken in the infrared wavelength by Webb instead of the optical light wavelength used by Hubble.
This new infrared image of NGC 346 taken by NASA’s James Webb Space Telescope’s Mid-Infrared Instrument (MIRI) traces emissions from cool gas and dust. In this image, blue represents silicates and sooty chemical molecules known as polycyclic aromatic hydrocarbons, or PAHs. More diffuse red emission shines from warm dust heated by the brightest and most massive stars in the heart of the region. Bright patches and filaments mark areas with abundant numbers of protostars.Image: NASA, ESA, CSA, STScI, Nolan Habel (NASA-JPL); Image Processing: Patrick Kavanagh (Maynooth University)
This image was taken using the Mid-Infrared Instrument (MIRI), Webb’s instrument that operates in the mid-infrared range. Unlike the other three instruments, which operate in the near-infrared, MIRI is particularly suited to highlighting dust and the intricate structures that it forms. The colors here represent different processes, as red shows the warm dust that is heated by bright nearby stars, while the blue regions represent areas dominated by molecules called polycyclic aromatic hydrocarbons.
You can see the contrast in how objects look at different wavelengths by comparing this image taken with MIRI to a previous James Webb image of the same region taken with its NIRCam instrument.
NGC 346, shown here in this image from NASA’s James Webb Space Telescope Near-Infrared Camera (NIRCam), is a dynamic star cluster that lies within a nebula 200,000 light-years away.SCIENCE: NASA, ESA, CSA, Olivia C. Jones (UK ATC), Guido De Marchi (ESTEC), Margaret Meixner (USRA) IMAGE PROCESSING: Alyssa Pagan (STScI), Nolan Habel (USRA), Laura Lenkić (USRA), Laurie E. U. Chu (NASA Ames)
This image focuses on the near-infrared, which is ideal for highlighting the presence of stars and the arcs of gas in the region, which is primarily hydrogen.
“By combining Webb data in both the near-infrared and mid-infrared, astronomers are able to take a fuller census of the stars and protostars within this dynamic region,” Webb scientists explain. “The results have implications for our understanding of galaxies that existed billions of years ago, during an era in the universe known as ‘cosmic noon,’ when star formation was at its peak and heavy element concentrations were lower, as seen in the SMC.”
Webb telescope captures Ring Nebula in gorgeous detail | Digital Trends
The James Webb Space Telescope has just served up a couple more sublime images, this time showing the Ring Nebula in astonishing detail.
First spotted in the 18th Century and located around 2,500 light-years from Earth, the Ring Nebula’s colorful main ring is made up of gas thrown off by a dying star at the center of the nebula.
This star will eventually become a white dwarf — a very small, dense, and hot core that marks the final evolutionary stage for a star, and one that our own sun will eventually follow, the European Space Agency (ESA) explains on its website.
Webb captured the images using two different cameras. The first one (below) was taken by its near-infrared camera (NIRCam) and shows the intricate details of the filament structure of the inner ring.
The Ring Nebula captured by Webb’s near-infrared camera (NIRCam).ESA/Webb, NASA, CSA, M. Barlow (University College London), N. Cox (ACRI-ST), R. Wesson (Cardiff University)
The second image (below) used Webb’s mid-infrared instrument (MIRI) to reveal particular details in the concentric features in the outer parts of the nebulae’s ring.
The Ring Nebula captured by Webb’s mid-infrared instrument (MIRI).ESA/Webb, NASA, CSA, M. Barlow (University College London), N. Cox (ACRI-ST), R. Wesson (Cardiff University)
The Ring Nebula, which ESA describes as being shaped like a “distorted donut,” contains around 20,000 dense globules that are rich in molecular hydrogen. In contrast, the inner region is an area of very hot gas.
“The main shell contains a thin ring of enhanced emission from carbon-based molecules known as polycyclic aromatic hydrocarbons,” ESA said. “Roughly 10 concentric arcs are located just beyond the outer edge of the main ring. The arcs are thought to originate from the interaction of the central star with a low-mass companion orbiting at a distance comparable to that between the Earth and the dwarf planet Pluto. In this way, nebulae like the Ring Nebula reveal a kind of astronomical archaeology, as astronomers study the nebula to learn about the star that created it.”
ESA notes that while the middle of the donut may appear to be empty, in reality it’s full of lower density material that stretches both towards and away from us, “creating a shape similar to a rugby ball slotted into the donut’s central gap.”
NASA, the European Space Agency, and the Canadian Space Agency have worked together on the $10 billion endeavor, building and deploying the world’s most powerful space telescope in a quest to make groundbreaking discoveries about the origins of the universe while at the same time searching for faraway planets that could support life.
What comes after Webb? NASA’s next-generation planet-hunting telescope | Digital Trends
NASA
When it comes to building enormous, complex space telescopes, agencies like NASA have to plan far in advance. Even though the James Webb Space Telescope only launched recently, astronomers are already busy thinking about what will come after Webb — and they’ve got ambitious plans.
The big plan for the next decades of astronomy research is to find habitable planets, and maybe even to search for signs of life beyond Earth. That’s the lofty goal of the Habitable Worlds Observatory, a space telescope currently in the planning phase that is aimed at discovering 25 Earth-like planets around sun-like stars.
We spoke to two of the scientists working on plans for this next-generation space telescope to find out more.
The power of direct imaging
One of the big challenges in finding habitable planets beyond our solar system is this: We can rarely actually see these far-off planets directly, because planets are so small and dim compared to stars. So to identify an exoplanet, astronomers generally infer its existence due to its effects on its host star. Currently, tools like the Hubble or James Webb space telescopes most often look for dips in a star’s brightness when a planet passes in front of it, called a transit, or they look for a wobble of the star caused by the gravity of the planet, called the radial velocity method.
“This is a multigenerational, probably multi-century endeavor that we’re on.”
Those methods give us clues, but to really understand exoplanets in depth, we need to be able to image them directly. Current telescopes are rarely able to do this because it requires such a high level of precision, but scientists are already planning out a next generation of space telescopes that will be able to take images of exoplanets.
The next big space telescope to be launched is the Nancy Grace Roman Space Telescope, scheduled to launch in 2027. It will perform a survey of the sky to estimate how many habitable exoplanets are out there. After that comes the Habitable World Observatory, a planned space telescope that will directly image Earth-like exoplanets around sun-like stars and which should launch around 2040. This will be the best chance we’ll have to date of discovering habitable Earth-like worlds where we could search for evidence of life beyond Earth.
Choosing the right wavelength
If you’ve followed the news about the James Webb Space Telescope, you’ve likely heard that it looks in the infrared part of the electromagnetic spectrum. That’s essential for its goal of studying the earliest galaxies, as it allows scientists to see galaxies with high levels of redshift. Infrared is also useful for looking through clouds of dust and seeing structures that would otherwise be hidden.
The plan for the Habitable Worlds Observatory, however, is to look in the optical and ultraviolet wavelengths. These wavelengths are useful for identifying the signatures of specific atoms such as hydrogen or oxygen, so we can point our instruments toward a planet and learn what its atmosphere is composed of.
There are all sorts of options for what particular atoms or compounds we could look for, but oxygen is the leading choice right now for what is called a biomarker, or a clue that indicates the potential presence of life. Spotting oxygen on a distant planet may be a sign that it warrants further inspection.
“There’s no perfect biomarker signature,” said David Sing of Johns Hopkins University, as we could also look for atoms like methane, and there’s always the possibility of a false positive, “but oxygen is a really important one.”
Oxygen also gives off a very strong signal, which makes it relatively easier to detect. In particular, ozone — which is a variation of oxygen with three atoms bound together — has a very strong signature in the ultraviolet wavelength. Think about how the ozone layer on Earth protects us from the ultraviolet radiation from the sun, and you can see how scientists could infer the presence of ozone on a distant planet if they saw a particular wavelength of ultraviolet light being blocked.
How to build an optical/UV telescope
With its focus on optical and ultraviolet wavelengths, the Habitable Worlds Observatory will be more similar to the Hubble Space Telescope than the James Webb Space Telescope. And that brings some advantages in terms of how you build a telescope.
Infrared telescopes like Webb are very sensitive to temperature (because when things get hot, they give off infrared radiation). So to work accurately, Webb needs to be cooled to extremely low operating temperatures of just a few Kelvin for some instruments. That makes the telescope more complex and expensive to build, as it requires a cryogenic cooling system.
For a telescope like the Habitable Worlds Observatory, that kind of extreme cooling isn’t necessary, which helps to keep the costs down.
NASA
Another key difference between infrared telescopes like Webb and optical/ultraviolet telescopes like the Habitable Worlds Observatory is the mirror. Webb’s primary mirror is coated with gold, which reflects infrared light very well. But an optical/ultraviolet telescope has a mirror coated with silver, which is more efficient at reflecting those wavelengths.
New technologies for a new decade
In some ways, we already know exactly what sorts of instruments will be required to look for habitable worlds, as these are updates to existing instruments rather than entirely new concepts.
For example, the instruments on Habitable Worlds will be somewhat similar to those on James Webb or Hubble, as they will consist of cameras and spectrographs. The cameras will be used to look for exoplanets in other star systems, and once a planet has been identified, it can be studied in more depth using the spectrographs. Spectrographs work by splitting incoming light into different wavelengths, to see which wavelengths have been absorbed. That tells you what the object that you’re looking at is composed of — and that’s how you can see whether an exoplanet has an atmosphere, and what that atmosphere is made of.
NASA
Refining these instruments and making them more accurate is not a trivial endeavor. In addition to direct detection, the next generation of space telescopes will also use techniques like radial velocity for identifying exoplanets. And more accurate spectrographs will enable techniques like extreme precision radial velocity, which allows more accurate measurements of the masses of exoplanets orbiting sun-like stars.
But more theoretical advances are required as well. One major factor required to improve our understanding of exoplanets, for example, is improving our understanding of stars. Stars can become brighter or dimmer for all sorts of reasons, and we need to be able to model this more accurately if we want to determine whether a variation is caused by the presence of an exoplanet, or is due to variation of the star.
Hunting for habitability
Even with a brand-new telescope equipped with brand-new technology, however, it won’t be a simple matter to find life beyond our solar system. That’s because habitability is a complex concept that requires more than just identifying an Earth-like planet orbiting a sun-like star.
“A planet that looks like it’s about the right brightness to be an Earth-sized planet, that has a roughly circular orbit in what we would call the habitable zone, shows some evidence for water vapor, maybe some oxygen, there’s no inner giant planet that has stirred things up, the star isn’t too active — that’s the kind of system we’re hoping to find as a candidate for a potentially habitable planet,” Scott Gaudi of the Ohio State University said.
NASA
But as tempting as it is to imagine a scenario where we build this telescope, find a habitable planet, then immediately detect life, that’s not how this will work, Gaudi said.
To properly search for habitable exoplanets, “we really have to get the whole context, which means studying the other planets in the systems, the debris disks, studying the stars,” Gaudi said. “That’s what’s really going to help us understand whether or not these planets are truly habitable.”
There’s a temptation to imagine that “we’re going to build the Habitable Worlds Observatory, we’re going to find life, and we’re done,” Gaudi said, but “it’s not going to work that way. If we’re lucky, we’re going to find one or two, maybe three, systems that look pretty promising. And then we’re going to have to build something even bigger and better.”
A multigenerational endeavor
Even if we’re able to find the ideal-looking system with a potentially habitable Earth-like world, then the next step would be to look at even more advanced factors, such as how much of the planet is covered by oceans and how much is land mass. Searching for life isn’t something that is going to be solved any time soon, but scientists are now laying the groundwork for Habitable Worlds Observatory to take on the next part of the job in 20 years’ time.
That’s similar to the way that planning for the James Webb Space Telescope began around 2000, and scientists today are just starting to be able to use this tool for discovery.
“Several decades ago, I was just a young student. But I’ve reaped the rewards of all that hard work that people did at the time,” Sing said. “And that generation of scientists felt that way because people did it for them with the Hubble Space Telescope. So there’s this legacy where you’re reaping the rewards of what senior scientists did 20 years ago. And you want to make sure that legacy will continue 20 years from now.”
NASA
Because wondering whether life could exist beyond Earth is one of the most profound questions facing science today, and it won’t be solved quickly. The Habitable Worlds Observatory is the next step on that journey, but it won’t be the end point.
“This is a multigenerational, probably multi-century endeavor that we’re on,” Gaudi said. “And I think that we should be optimistic about that process, but we should also be humble.”
What comes after Webb? NASA’s next-generation planet-hunting telescope | Digital Trends
NASA
When it comes to building enormous, complex space telescopes, agencies like NASA have to plan far in advance. Even though the James Webb Space Telescope only launched recently, astronomers are already busy thinking about what will come after Webb — and they’ve got ambitious plans.
The big plan for the next decades of astronomy research is to find habitable planets, and maybe even to search for signs of life beyond Earth. That’s the lofty goal of the Habitable Worlds Observatory, a space telescope currently in the planning phase that is aimed at discovering 25 Earth-like planets around sun-like stars.
We spoke to two of the scientists working on plans for this next-generation space telescope to find out more.
The power of direct imaging
One of the big challenges in finding habitable planets beyond our solar system is this: We can rarely actually see these far-off planets directly, because planets are so small and dim compared to stars. So to identify an exoplanet, astronomers generally infer its existence due to its effects on its host star. Currently, tools like the Hubble or James Webb space telescopes most often look for dips in a star’s brightness when a planet passes in front of it, called a transit, or they look for a wobble of the star caused by the gravity of the planet, called the radial velocity method.
“This is a multigenerational, probably multi-century endeavor that we’re on.”
Those methods give us clues, but to really understand exoplanets in depth, we need to be able to image them directly. Current telescopes are rarely able to do this because it requires such a high level of precision, but scientists are already planning out a next generation of space telescopes that will be able to take images of exoplanets.
The next big space telescope to be launched is the Nancy Grace Roman Space Telescope, scheduled to launch in 2027. It will perform a survey of the sky to estimate how many habitable exoplanets are out there. After that comes the Habitable World Observatory, a planned space telescope that will directly image Earth-like exoplanets around sun-like stars and which should launch around 2040. This will be the best chance we’ll have to date of discovering habitable Earth-like worlds where we could search for evidence of life beyond Earth.
Choosing the right wavelength
If you’ve followed the news about the James Webb Space Telescope, you’ve likely heard that it looks in the infrared part of the electromagnetic spectrum. That’s essential for its goal of studying the earliest galaxies, as it allows scientists to see galaxies with high levels of redshift. Infrared is also useful for looking through clouds of dust and seeing structures that would otherwise be hidden.
The plan for the Habitable Worlds Observatory, however, is to look in the optical and ultraviolet wavelengths. These wavelengths are useful for identifying the signatures of specific atoms such as hydrogen or oxygen, so we can point our instruments toward a planet and learn what its atmosphere is composed of.
There are all sorts of options for what particular atoms or compounds we could look for, but oxygen is the leading choice right now for what is called a biomarker, or a clue that indicates the potential presence of life. Spotting oxygen on a distant planet may be a sign that it warrants further inspection.
“There’s no perfect biomarker signature,” said David Sing of Johns Hopkins University, as we could also look for atoms like methane, and there’s always the possibility of a false positive, “but oxygen is a really important one.”
Oxygen also gives off a very strong signal, which makes it relatively easier to detect. In particular, ozone — which is a variation of oxygen with three atoms bound together — has a very strong signature in the ultraviolet wavelength. Think about how the ozone layer on Earth protects us from the ultraviolet radiation from the sun, and you can see how scientists could infer the presence of ozone on a distant planet if they saw a particular wavelength of ultraviolet light being blocked.
How to build an optical/UV telescope
With its focus on optical and ultraviolet wavelengths, the Habitable Worlds Observatory will be more similar to the Hubble Space Telescope than the James Webb Space Telescope. And that brings some advantages in terms of how you build a telescope.
Infrared telescopes like Webb are very sensitive to temperature (because when things get hot, they give off infrared radiation). So to work accurately, Webb needs to be cooled to extremely low operating temperatures of just a few Kelvin for some instruments. That makes the telescope more complex and expensive to build, as it requires a cryogenic cooling system.
For a telescope like the Habitable Worlds Observatory, that kind of extreme cooling isn’t necessary, which helps to keep the costs down.
NASA
Another key difference between infrared telescopes like Webb and optical/ultraviolet telescopes like the Habitable Worlds Observatory is the mirror. Webb’s primary mirror is coated with gold, which reflects infrared light very well. But an optical/ultraviolet telescope has a mirror coated with silver, which is more efficient at reflecting those wavelengths.
New technologies for a new decade
In some ways, we already know exactly what sorts of instruments will be required to look for habitable worlds, as these are updates to existing instruments rather than entirely new concepts.
For example, the instruments on Habitable Worlds will be somewhat similar to those on James Webb or Hubble, as they will consist of cameras and spectrographs. The cameras will be used to look for exoplanets in other star systems, and once a planet has been identified, it can be studied in more depth using the spectrographs. Spectrographs work by splitting incoming light into different wavelengths, to see which wavelengths have been absorbed. That tells you what the object that you’re looking at is composed of — and that’s how you can see whether an exoplanet has an atmosphere, and what that atmosphere is made of.
NASA
Refining these instruments and making them more accurate is not a trivial endeavor. In addition to direct detection, the next generation of space telescopes will also use techniques like radial velocity for identifying exoplanets. And more accurate spectrographs will enable techniques like extreme precision radial velocity, which allows more accurate measurements of the masses of exoplanets orbiting sun-like stars.
But more theoretical advances are required as well. One major factor required to improve our understanding of exoplanets, for example, is improving our understanding of stars. Stars can become brighter or dimmer for all sorts of reasons, and we need to be able to model this more accurately if we want to determine whether a variation is caused by the presence of an exoplanet, or is due to variation of the star.
Hunting for habitability
Even with a brand-new telescope equipped with brand-new technology, however, it won’t be a simple matter to find life beyond our solar system. That’s because habitability is a complex concept that requires more than just identifying an Earth-like planet orbiting a sun-like star.
“A planet that looks like it’s about the right brightness to be an Earth-sized planet, that has a roughly circular orbit in what we would call the habitable zone, shows some evidence for water vapor, maybe some oxygen, there’s no inner giant planet that has stirred things up, the star isn’t too active — that’s the kind of system we’re hoping to find as a candidate for a potentially habitable planet,” Scott Gaudi of the Ohio State University said.
NASA
But as tempting as it is to imagine a scenario where we build this telescope, find a habitable planet, then immediately detect life, that’s not how this will work, Gaudi said.
To properly search for habitable exoplanets, “we really have to get the whole context, which means studying the other planets in the systems, the debris disks, studying the stars,” Gaudi said. “That’s what’s really going to help us understand whether or not these planets are truly habitable.”
There’s a temptation to imagine that “we’re going to build the Habitable Worlds Observatory, we’re going to find life, and we’re done,” Gaudi said, but “it’s not going to work that way. If we’re lucky, we’re going to find one or two, maybe three, systems that look pretty promising. And then we’re going to have to build something even bigger and better.”
A multigenerational endeavor
Even if we’re able to find the ideal-looking system with a potentially habitable Earth-like world, then the next step would be to look at even more advanced factors, such as how much of the planet is covered by oceans and how much is land mass. Searching for life isn’t something that is going to be solved any time soon, but scientists are now laying the groundwork for Habitable Worlds Observatory to take on the next part of the job in 20 years’ time.
That’s similar to the way that planning for the James Webb Space Telescope began around 2000, and scientists today are just starting to be able to use this tool for discovery.
“Several decades ago, I was just a young student. But I’ve reaped the rewards of all that hard work that people did at the time,” Sing said. “And that generation of scientists felt that way because people did it for them with the Hubble Space Telescope. So there’s this legacy where you’re reaping the rewards of what senior scientists did 20 years ago. And you want to make sure that legacy will continue 20 years from now.”
NASA
Because wondering whether life could exist beyond Earth is one of the most profound questions facing science today, and it won’t be solved quickly. The Habitable Worlds Observatory is the next step on that journey, but it won’t be the end point.
“This is a multigenerational, probably multi-century endeavor that we’re on,” Gaudi said. “And I think that we should be optimistic about that process, but we should also be humble.”
How Webb instruments work together to create views of space | Digital Trends
A series of new images from the James Webb Space Telescope shows the dusty, irregular galaxy NGC 6822 — and the different views captured by various Webb instruments.
Located relatively close by at 1.5 million light-years from Earth, this galaxy is notable for its low metallicity. Confusingly, when astronomers say metallicity they do not mean the amount of metals present in a galaxy, but rather the amount of all heavy elements — i.e., everything which isn’t hydrogen or helium. This factor is important because the very earliest galaxies in the universe were made up almost entirely of hydrogen and helium, meaning they had low metallicity, and the heavier elements were created over time in the heart of stars and were then distributed through the universe when some of those stars went supernova.
This image shows the irregular galaxy NGC 6822, which was observed by the Near-InfraRed Camera (NIRCam) and Mid-InfraRed Instrument (MIRI) mounted on the NASA/ESA/CSA James Webb Space Telescope. As their names suggest, NIRCam and MIRI probe different parts of the electromagnetic spectrum. This allows the instruments to observe different components of the same galaxy, with MIRI especially sensitive to its gas-rich regions (the yellow swirls in this image) and NIRCam suitable for observing its densely packed field of stars.ESA/Webb, NASA & CSA, M. Meixner
This image from Webb combines data from two of its instruments, the Near-InfraRed Camera (NIRCam) and the Mid-InfraRed Instrument (MIRI), to show off features like the clouds of dust (shown in yellow) and areas of active star formation (seen in red).
To understand how scientists build up images like this out of different observations, Webb researchers also released the individual views taken by NIRCam and MIRI. Because the two instruments look in different parts of the spectrum — NIRCam in the near-infrared and MIRI in the mid-infrared — they can pick out different features. When the two views are combined, they show even more detail than one view could alone.
This image shows the irregular galaxy NGC 6822, as observed by the Mid-InfraRed Instrument (MIRI) mounted on the NASA/ESA/CSA James Webb Space Telescope. MIRI probes the mid-infrared, which in this case makes it perfectly suited to observe the dense regions of gas that suffuse this galaxy.ESA/Webb, NASA & CSA, M. Meixner
This is the MIRI image, which highlights regions of dust that are more noticeable in the mid-infrared. The cooler areas of dust are in blue, while warmer dust clouds are seen in orange. And the different colors can help pick out different galaxies too, with nearby galaxies appearing green and more distant galaxies seen in orange. There is even a bright orange ring shape near the center bottom which is the remnant of a supernova.
This scaled image shows the irregular galaxy NGC 6822, which was observed by the Near-InfraRed Camera (NIRCam) mounted on the NASA/ESA/CSA James Webb Space Telescope.ESA/Webb, NASA & CSA, M. Meixner
This is the NIRCam image, which picks out the thousands of stars visible to Webb which are hard to see in the MIRI image. In this wavelength, NIRCam can peer through the dust and see the stars which would otherwise be hidden, with the brightest stars glowing in blue and fainter stars in red.
If you’d like to see a slider comparison of the MIRI and NIRCam images, that is also available on the Webb website.
