As a New Yorker, I would say that trying to catch a glimpse of the star from Times Square is a fool’s errand. You’d have to squint past fluorescent street lamps, flashing billboards, stock exchanges, and other light distractions to catch even the faintest glimmer. It is better to take the train about a hundred miles up. Out there, stargazing no longer requires any effort. A stunning canopy of glitter floats over you whether you like it or not.
But even from the deepest, darkest and most distant place, you will never see every star with the naked eye. You cannot physically record all the galaxies, nebulae, exoplanets, quasars – I could go on – in your field of view, even with your favorite optical telescope. There are billions and billions (billions) of other cosmic phenomena. It’s just that our human eyes aren’t built to see the light they emit. It’s called infrared light.
So many cosmic treasures are invisible to us. Fortunately, this does not mean that they are beyond us.
As Stephen Hawking once noted, humans are unique in that we always find a way to overcome our mortal limits. We do it “with our minds and our machines”. And sure enough, over the years astronomers have developed fascinating infrared solutions—which eventually paved the way for NASA’s James Webb Space Telescope.
The fight against human limitation
Big-budget space telescopes like NASA’s Hubble and Spitzer are already shedding light on some cosmic infrared mysteries. They contain instruments that scan the sky for elusive light and then convert that information into signals that can be understood by human pupils. This in turn allows us to see many things in space that are normally hidden from our eyes.
However, if these massive telescopes are episode one and two of a series of astronomical infrared detections, a powerful new one Webb Space Telescope — of which the first full set of images will be released on July 12 — is a brand new season.
Levels beyond the infrared capabilities of Hubble and Spitzer, JWST is literally built for the job.
The pioneering telescope is a $10 billion gold-plated machine equipped with infrared detectors, highlighted by cutting-edge lenses and programmed with ultra-powerful software. His holy grail device is called the Near Infrared Camera, or Nircam, and it will lead the charge by collecting masses of deep-space infrared signals that astronomers can observe on the ground.
This is why JWST is often said to hold the promise of revealing the “unfiltered universe.”
Looking through the JWST lens instead of a standard optical telescope would be like looking at the stars from my hypothetical New York dark zone instead of Times Square. In both cases, there would be a lot more sparks, even if you are looking at the same sky. It’s just that in our shadowy dark zone analogy, we’re observing more stars because we’re not hampered by light pollution. JWST, on the other hand, collects the infrared light of deep space and decodes it for us.
It will point to the exact same universe that Hubble has explored for decades and scientists have studied for ages, but it will have access to luminescence that we can’t see, and perhaps reveal hidden phenomena carried by the universe, such as violent black holes, exotic exoplanets, the great spiral. galaxies and… maybe even signals of extraterrestrial life?
His first images are undoubtedly ready to take much more than our breath away. In fact, NASA workers who have already seen the JWST “first light” images say they were moved to tears. “What I saw moved me as a scientist, as an engineer, and as a person,” said Pam Melroy, NASA’s deputy administrator.
But before we get into the specifics of JWST’s infrared mechanics, we need to talk about the electromagnetic spectrum. Or rather, a bit of a conundrum that it presents to us humans.
Why can’t we see infrared light?
At some point in your life, you may have wondered what it would be like to see a new color. The kind that cannot be described, the way “green” really has no definition other than “the shade of a caterpillar” – or, if you’re a fan of objectivity, “550 nanometer wavelength”. After thinking about it for a while, I’d bet that you’ve settled into an unsettling reality that you’ll never know the answer to.
This is because colors are nothing more than the products of light reflecting off some source.
Different colors are dictated by different wavelengths of light, which you can think of as curves of different proportions. When we see a blue umbrella, for example, our eyes pick up the tighter blue wavelengths emanating from the waterproof material. While admiring the fiery sunset, our eyes perceive a lot of longer, more relaxed red and yellow wavelengths.
All these wavelengths are neatly arranged along what is known as the “electromagnetic spectrum”. But here’s the problem.
Although there are an infinite number of wavelengths of light, humans can only “see” one small part of the spectrum: the region of visible light that encapsulates the colors of the rainbow. This is precisely why we never experience the pleasure of looking at any color other than the rainbow.
Our bodies won’t allow it, and there’s nothing we can do to change it—except, of course, to build a super-powerful telescope.
Spying on secret wavelengths
Because infrared light falls outside the range of visible light, it does not appear red, despite its name. It doesn’t look like anything. It’s actually better described as a heat signature – we can “feel” infrared wavelengths, which is why many thermal imaging devices include infrared detectors. For example, firefighters use infrared to see where a fire may be burning in a building without having to go inside.
But specifically for astronomy, the main problem is the invisibility of infrared wavelengths.
The universe is expanding. Constantly. Which means that as you read this, stars, galaxies and quasars – superluminescent objects that act as cosmic flashlights – are moving further and further away from Earth. And as they do, the wavelengths of light they emit gradually stretch from our perspective, sort of like stretching a rubber band. They stretch and tilt and stretch until they move towards the red end of the spectrum. “They are redshifting”.
Take, for example, a star that was born near the beginning of time. At some point, once Earth was formed, this star may have emitted wavelengths of blue light toward our young planet. But as it moved away, in tandem with the expansion of space, those wavelengths of blue light began to stretch away from Earth’s vantage point, becoming redder… and redder… and redder.
“Redshifting is the stretching of light toward longer wavelengths that occurs as light travels through the expanding universe and can be used to measure distance,” said Paul Geithner, deputy project manager for JWST.
In fact, he said, Nircam JWST “takes a series of images using filters that capture different wavelengths and uses the brightness changes it detects between those images to estimate the redshifts of distant galaxies.”
Eventually, however, these wavelengths extend beyond the limits of the visible light spectrum. They tread into infrared waters – and disappear from the sight of our naked eye. Consider again the ancient star example.
Now, billions of years later, these slowly reddening wavelengths have moved from our perspective into the infrared region of the spectrum. The ancient star sends us only the kind of starlight that our eyes cannot see.
Stars and galaxies, MIA
This means that all distant, super-rare, and probably information-rich stars and galaxies are invisible to us, along with everything that those stars and galaxies illuminate. We are the missing pieces of our universe’s history – its opening chapters.
But thanks to their infrared hunting instruments, JWST’s infrared detectors were able to show us the missing pieces. They could shed light on what the universe looked like in the first moments after the big bang. They could also find distant exoplanets floating among their own exomoons and search for distant artificial light that could signal alien life. They offer us a landscape of space that is bright enough to remind us of our microscopic place in it.
To take things a step further, infrared wavelengths have the added advantage of being long enough to travel through matter, including dense, huge clouds of stardust. So if JWST picks up the infrared light emitted from such a cloud, it will be able to paint a picture of the scene inside—perhaps even the scene of ancient stars being born.
“It’s not clear how the universe transformed from a simpler state of nothing but hydrogen and helium to the universe we see today,” Geithner said. “[T]The Webb Telescope will see the far reaches of the universe and an epoch of time that we have not yet observed, and will help us answer these important questions.”
But the most sought-after aspect of JWST is that, in addition to questions scientists have been asking for decades, it may very well answer a few questions no one has thought to ask.