We Have Now Reached The Limits Of The Hubble Space Telescope
“Finally, there are the wavelength limits as well. Stars emits a wide variety of light, from the ultraviolet through the optical and into the infrared. It’s no coincidence that this is what Hubble was designed for: to look for light that’s of the same variety and wavelengths that we know stars emit.
But this, too, is fundamentally limiting. You see, as light travels through the Universe, the fabric of space itself is expanding. This causes the light, even if it’s emitted with intrinsically short wavelengths, to have its wavelength stretched by the expansion of space. By the time it arrives at our eyes, it’s redshifted by a particular factor that’s determined by the expansion rate of the Universe and the object’s distance from us.
Hubble’s wavelength range sets a fundamental limit to how far back we can see: to when the Universe is around 400 million years old, but no earlier.”
The Hubble Space Telescope, currently entering its 30th year of service, has literally revolutionized our view of the Universe. It’s shown us our faintest and most distant stars, galaxies, and galaxy clusters of all. But as far back as it’s taken us, and as spectacular as what it’s revealed, there is much, much more Universe out there, and Hubble is at its limit.
Here’s how far we’ve come, with a look to how much farther we could yet go. It’s up to us to build the tools to take us there.
One Galaxy Cluster, Through Hubble’s Eyes, Can Show Us The Entire Universe
“There’s more gravity than the gas can provide, showing the presence of non-baryonic dark matter.
But all the mass, combined, contributes to gravitational lensing.
The bending of space stretches and magnifies the light from galaxies behind the cluster.
This is the whole purpose of the joint Hubble/Spitzer RELICS program, highlighted by this galaxy cluster.”
Want to see the most distant galaxy in the Universe? You don’t simply need the world’s greatest telescopes; you also need an assist from gravity. Galaxy clusters provide the largest gravitational sources in the Universe, thereby providing the largest natural magnification enhancements through gravitational lensing. While the internal dynamics of the galaxies tell us that there must be dark matter present, and that dark matter is something other than normal (atom-based) matter, the overall gravitational effects enhance any telescope-based views of the Universe. The joint Hubble/Spitzer RELICS program is imaging 41 of these massive galaxy clusters, hoping to magnify ultra-distant galaxies more distant than any we’ve ever seen before. When the James Webb Space Telescope comes online, these will be the places where our greatest target candidates for “most distant galaxy in the Universe” will come from.
The next step of our great cosmic journey is beginning right now. Come get a glimpse of the future for yourself!
How The James Webb Space Telescope Will Deploy (In An Ideal World)
“Once the launch vehicle reaches a distance of 10,000 kilometers from Earth, just a half hour into its journey, the telescope separates from the upper stage of the rocket. At this point, JWST is free from the launch vehicle, and is now on its own, on its way to its ultimate destination. Two minutes later, the first key, but difficult step must succeed: to deploy its solar array. James Webb has a battery on board, but will only need it until the array is deployed. The thrusters will then fire, pointing the solar panels towards the Sun and orienting the observatory properly for the next step. If the array fails, the battery will last only a few hours. This step, like a great many, is a single-point-of-failure for the entire mission.”
The James Webb Space Telescope is optimized for uncovering so many secrets of the Universe, it’s impossible to list them all in a single article. From the first stars and galaxies to atmospheres around Earth-sized worlds, from the molecules present in newly-forming planets to direct images of Jupiter-sized worlds in distant solar systems, and from the pristine material left over from the Big Bang to finding the majority of water in the Universe, James Webb will answer questions that no observatory has ever addressed before. But only if it successfully launches and deploys! This takes a tremendous amount of work from vastly separate teams, all coming together without a single failure. Yet the plans have been vetted and tested as thoroughly as possible from the ground, and once the final preparatory steps are taken later this year, all that remains will be to execute the plan.
What has to happen in order for James Webb to successfully launch, deploy, and get onto the science? Find out, in-depth, today!
Do Earth-Sized Planets Around Other Stars Have Atmospheres? James Webb Will Find Out!
“Even so, because of its ability to measure light to high sensitivity far into the infrared, there’s a remarkable hope for determining whether these worlds have atmosphere regardless of any other measurements. As planets orbit their star, we see different phases: a full phase when it’s on the far side of the star; a new phase when it’s on the near side, and everything in between. Based on the temperature of the world at night, we’ll receive different amounts of infrared light from the "dark” side that faces away from the Sun. Even without a transit, James Webb should be able to measure this.“
The overwhelming majority of Earth-sized, potentially habitable planets that Kepler found are in orbit around red dwarf stars. In many ways, this is great: red dwarf stars are stable, temperature-wise, for longer than our Sun. Their planets are easier to detect, and they will be the first Earth-sized ones we can measure the atmospheres of directly. But even if we can’t make those measurements with James Webb, we’ll be able to learn whether they have atmospheres or not via a different method: by measuring the infrared radiation coming from the planets themselves in various phases. Just as we can measure the presence of Venus’ atmosphere from the hot, infrared radiation emanating from it even on the night side, we can make those same measurements with James Webb of other Solar Systems. By time the early 2020s roll around, we’ll have our first answers to this longstanding debate.
Many scientists think that Earth-sized planets around M-class stars will have no atmospheres left; others think there’s a chance they survive. Here’s how James Webb will find out!
When Did The First Stars Appear In The Universe?
“But there’s more science to be done. Even with James Webb, we likely won’t get all the way to the very first star of all, but we’re very likely to gain a much better handle on exactly where they are and when they are. And as for the first pristine stars? The first stars verified to have nothing other than hydrogen and helium in them? If nature is kind to us, James Webb won’t only bring us the very first one of those, but will bring us many examples.
The Universe is out there, waiting for us to discover it. If we want to know the answer, all we need to do is look. As we build better observatories and take better data, our understanding of all that’s out there will only improve.”
If we look out as far as we can, there’s a big gap between what we know and what must be there. The most distant galaxy we’ve ever found is GN-z11, whose light comes from when the Universe was only 400 million years old. The next picture we have is the cosmic microwave background, emitted from when the Universe was a mere 380,000 years old. At that point, there were no stars; by time we get to 400 million years of age, we have quite large and bright galaxies. So when did the first stars actually, truly appear? It’s a question that we know an awful lot about what the answer must look like, but we’re still a few steps away from actually finding them.
Come find out all we know, and check out a video that Paul Matt Sutter and I made together explaining what we know… and what comes next!
Ask Ethan: How Much Of The Observable Universe Are We Failing To See?
“The Hubble Deep Field saw approx. 13+ Billion Light Years in one direction, so can we can assume we would see 13+ Billion in all directions? The deep field picture showed infant galaxies that are misshapen and just short of the first stars. The big bang itself lies just beyond. Does this imply that the entire universe is roughly 26+ Billion Light Years across? How is it that I have seen estimates showing we only see a small percentage of all the structure that is out there in our universe?”
When we look out at the distant Universe with our most powerful telescopes, as far as we can possibly see, what do we find? Galaxies, smaller and fainter and more and more distant, as far as we’re capable of looking. We have yet to hit the limit of where the galaxies come to an end; as far as we’ve ever been able to look, we’ve found light. Yet at some point, they must cease. There can’t be an infinite number of galaxies in a finite volume of space, and since the Universe has only had 13.8 billion years since the Big Bang, there has to be a finite number of galaxies, and a point beyond which they no longer exist. The deepest view of the Universe, the Hubble eXtreme Deep Field, revealed 5,500 galaxies in a volume comprising just 1/32,000,000th of the sky. But even that appears to be less than 10% of the galaxies out there in the Universe, despite containing galaxies much more distant than 13.8 billion light years.
How does this all make sense? And what do we know about what we haven’t yet seen? Find out on this week’s Ask Ethan!
Ask Ethan: Why Was The Universe Dark For So Long?
“One thing I wonder though is why did the dark ages last hundreds of millions of years? I would have expected an order of magnitude smaller, or more.”
There’s a troubling puzzle when it comes to the Universe: the so-called ‘dark ages’ don’t come to an end until 550 million years after the Big Bang. But this is a big problem when you consider that we’ve already imaged a galaxy from when the Universe was only 400 million years old, and that we fully anticipate the first stars to form when the Universe is only 50-100 million years old. So what’s with all the darkness, then? And how do we expect the James Webb Space Telescope to see back to the very first galaxies? The answer lies in two parts. First, even though you have stars, the Universe is still filled with neutral atoms, which block visible and ultraviolet light. We need to ionize those atoms in order to have a transparent Universe, and that takes lots of time. But the second key is that the Universe, even with neutral atoms, is quite transparent to other wavelengths of light, like infrared light. And that’s where an observatory like James Webb is going to be looking!
The Universe was dark for so long because it doesn’t just need light, it needs for all the light-blocking material to disappear. But we’re going to overcome that obstacle in less than two years anyway, and that’s something we should all be excited about!
What The James Webb Space Telescope Will Do For Science
Right around one year from today, the James Webb Space Telescope will launch to a position 1.5 million kilometers away from Earth, deploying into a quasi-stable orbit around the L2 Lagrange point. Its magnificent, 5-layer sunshield will unfold, allowing it to passively cool down to temperatures cold enough to turn nitrogen into a liquid. Beyond that, it will have on-board coolant taking it down to 7 Kelvin, allowing us to observe light that’s 50 times as long as the wavelengths the human eye can see. The gold mirrors are ideal for reflecting infrared light, and will allow us to view the Universe as never before.
This isn’t the “next Hubble” as some are saying, but rather the first James Webb! Here’s what’s in store, and what makes it so magnificent.
5 Surprising Facts About The First Galaxies In The Universe
“1.) There are no rocky planets present among the very first stars and galaxies. Whenever you form stars from a molecular cloud of gas, you can fully expect that gas to fragment into a whole slew of clumps, which grow at different rates depending on how large they are to begin with and what else is in their vicinity. Large gas clouds will grow stars and planets of many different sizes, but even the smallest worlds that first form will be made exclusively of gas: hydrogen and helium. Without any previous generations of stars, there are no heavier elements to form solid bodies like rocky planets or moons. Small balls of gas may form, but when those stars ignite, they’ll simply be burned off into interstellar space by the ionizing radiation of those first nuclear fires in the Universe.”
Looking farther and farther into the distant Universe is the equivalent of looking farther and farther back in time. Although Hubble has shown us galaxies from when the Universe is just 400 million years old, and satellites to measure the Cosmic Microwave Background can show us a snapshot at 380,000 years, we have no information about what’s in between. That means, to date, we have yet to see the Universe’s first stars and galaxies! While James Webb will shed a new cosmic light on that era, allowing us to view these galaxies for the first time, there are some pieces of information that we already know. These galaxies must be tiny compared to the ones we have today; they will never be seen by Hubble, even with an infinite amount of observing time; they should already contain the seeds of supermassive black holes from their inception; and they very likely contain the most massive stars found in the entire Universe.
Come find out five surprising facts about the very first galaxies in the Universe, and learn what James Webb will allow us to finally know for certain!