You might have scrolled through social media one day and found these photos of space—usually accompanied with high interactions from page fans, like likes and shares. Oftentimes even proper news sources will find themselves sharing photos taken by one or two telescopes out there.
“Wow,” you might find yourself uttering under your breath. True enough, photos of space can quite literally be out of this world, and are often met with intrigue and awe when revealed to the public. The things we see in space with our ground-based telescopes can sometimes show truly beautiful pieces of stars, or even galaxies and planets.
So, you decide to take things into your own hands—eyes, really—and you look up to the sky. Then it dawns on you: there’s nothing there. Sure, you see a star here and there, and the Moon may be somewhere within your field of view. Other than that, there’s not much out there. No beautiful nebulae, no stunning spiral galaxies—all stars. So what gives?
Different Eyes For Different Lights
The key to your space-viewing problems are rooted in precisely that—your viewing. Or, to be more precise, it’s the way in which we humans view the universe, along with every other thing within our field of view: stars, the sky, that flower over there, and everything in between.
The light that we do manage to see in our everyday viewing is but a small sliver of the entire “spectrum” of wavelengths of radiation referred to as the electromagnetic spectrum. Visible light is a small segment somewhere in there, rooted in between infrared radiation, which we sense as heat, and ultraviolet radiation, which we kindly try to avoid getting on our skin with sunscreen.
Thing is, stuff that’s out there in the universe actually “shines” in light beyond the spectrum that we can see. As mentioned before, we certainly can’t see infrared radiation, but we can definitely feel it as heat; similarly, anything that radiates heat “shines” in the infrared spectrum—us humans included. Thermal cameras take advantage of this very phenomenon to measure your body temperature without ever touching your body.
We humans had to engineer our way around our visual limitations, while nature already managed to find organic ways around the issue. Some fish and snakes can see in infrared, which enables them to spot prey in the absence of light. Some insects and birds, on the other hand, can see the world in ultraviolet light, allowing them to spot patterns in each other that are invisible to us humans without the use of special tools.
And much like the rest of nature whose patterns are normally hidden to us, the universe too is bathed in all kinds of radiation. In fact, the spectrum stretches from the longest wavelengths, radio waves, to the shortest-wavelength gamma radiation. (And yes, the signals giving you or your parents their favorite radio stations are a kind of light, too.)
Astronomers figured out later on that they can’t rely on visible light to view the cosmos. Sure, the stars out there are clearly visible on cloudless nights; they can spot planets like Jupiter and Saturn on a good night, too, and maybe spot a swath of our stellar neighbors along our spot in the Milky Way Galaxy if they’re in the right place at the right time.
It took scientific innovations, however, to truly enable us to peer into the universe like we hadn’t been able to before. It’s for this reason that astronomical telescopes—perhaps ground-based, like the one atop Mauna Kea in Hawaii, or up in space like the Hubble Space Telescope and, hopefully soon, the James Webb Space Telescope—need all the technology that they carry now. With the help of advanced imaging technology, scientists were given ways to view the cosmos in ways their normal eyes couldn’t.
They soon figured out that viewing the universe in wavelengths beyond the visible spectrum were necessary, too. The expanding universe also “stretches out” the light that passes through it, meaning any distant galaxies will have had their visible light wavelengths stretched out into infrared by the time they reach us here on Earth.
This is the reason why those images of galaxies look the way they do in your social media feed; they’re usually viewed in other wavelengths, then processed as an image that we can view on our phones, sans special telescopes.
In viewing the sky in infrared light, which can travel farther distances compared to visible light and can pass through gas clouds that can otherwise obfuscate normal viewing in visible light, scientists can peer behind nebulae and gas clouds that sit in a direct path between us on Earth and the stars and galaxies behind the nebula, “screening out” the nebula in the process. (This process is made most visible in an interactive setup used by NASA’s exploration of light and how its telescopes view it.)
A particular cosmic image called GOODS North was also spotted in infrared; the subject is a distant galaxy called GN-z11, and is estimated to sit at a whopping 13.4 billion light-years away. We basically see GN-z11 as it was 11.4 billion years ago, and the light has been stretched thin by the expanding universe in all that time that it took to reach us.
In fact, an infrared sky survey accepting contributions from citizen scientists is what discovered the “accidental” brown dwarf zooming through our galaxy, giving scientists a rare glimpse into rogue “failed” stars called brown dwarfs. Astronomers peer at the sky in other wavelengths aside from infrared, too; keeping detectors that sense radio waves targeted out to the sky enables astronomers to spot the mysterious radio source emanating from our galactic center.
We can even take advantage of our new set of eyes to view objects that are closer to home. Much like how visible light reflects differently from different objects, gases and compounds also absorb and reflect other wavelengths of light differently, too. It’s this particular property that enables the viewing of our neighbor planets like Saturn. In doing so, we give ourselves a fresh glimpse into the planet’s inner workings, revealing properties that would have been otherwise hidden by simple visible light, like atmospheric composition and the composition of its planetary rings.
Looking Up
So, there you have it. Telescopes equipped to see the cosmos beyond visible light make it possible for us humans to see the universe in our phones in such vivid colors and details. It’s the development of these technologies that enable scientists to give color to our skies that would have otherwise remained very dark. In doing so, we get a new set of eyes to view the universe, revealing details to us that we would have never noticed had we just stared at the sky blankly all this time.
Future developments into these enabling technologies, like the soon-to-be-deployed James Webb Space Telescope, should give us even clearer eyes, allowing scientists—and us in response—to peer even farther into our universe’s past.
References
- Belleville, M. (2019, September 27). Explore—Light [Text]. NASA. http://www.nasa.gov/content/explore-light
