Ask Ethan: What Will Our First Direct Image Of An Earth-Like Exoplanet Look Like?
“[W]hat kind of resolution can we expect? [A] few pixels only or some features visible?”
I’ve got good news and bad news. With the next generation of space-based and ground-based telescopes on the way, we’ll finally be able to image Earth-sized and super-Earth-sized planets around the nearest stars to us directly. Unfortunately, even the largest of these telescopes won’t be able to resolve these planets beyond being a single pixel (with light leaking into the adjacent pixels) in angular size. But even with that limitation, we should be able to recover signatures of continents, oceans, icecaps, clouds, atmospheric contents, water, and potentially even life.
Come find out what we will (and won’t) be able to do with our first direct images of Earth-sized exoplanets, coming to you in just a few years!
This Is How We Will Discover The Most Distant Galaxy Ever
“Sometime in the distant past, likely when the Universe was less than 2% its current age, the very first galaxy of all formed when massive star clusters merged together, resulting in an unprecedented burst of star formation. The high-energy light from these stars struggles to escape, but the longer-wavelength light can penetrate farther through neutral atoms. The expansion of the Universe redshifts all the light, stretching it far beyond anything Hubble could potentially observe, but next-generation infrared telescopes should be able to catch it. And if we observe the right part of the sky, with the right instruments, for a sufficiently long time to reveal the right details about these objects, we’ll push back the cosmic frontier of the first galaxies even farther.
Somewhere, the most distant, first galaxy of all is out there, waiting to be discovered. As the 2020s approach, we can feel confident that we’ll not only shatter the current cosmic record-holder, but we know exactly how we’ll do it.”
13.8 billion years ago, our Universe as-we-know-it began with the hot Big Bang. There were no stars or galaxies back then; there weren’t even bound structures of any type. Everything was too energetic, and would immediately be destroyed by the unfathomably high temperatures and energies that every particle possessed. Yet, with time, the Universe expanded and cooled. Protons, nuclei, and neutral atoms formed; overdense regions gravitationally pulled-in mass and matter; stars were born, lived, died, and new stars were born in their aftermath. At some point, the first large star clusters merged together, passing a critical threshold and forming the first galaxy in the Universe.
That’s what we want to find. We’ve gone back to when the Universe was just 3% its present age, but that’s not enough. We must go father. We must find the first one. Here’s how we’ll do it.
Happy Halloween from Starts With A Bang!
In a first, I have gone full-astrophysics for Halloween this year.
In all its golden glory, I have put together a James Webb Space Telescope costume this year, complete with sunshield and all!
Happy Halloween, Tumblr!
This Is How Hubble Will Use Its Remaining Gyroscopes To Maneuver In Space
“It might seem to be just another example of crumbling infrastructure in the United States, but you must neither underestimate Hubble nor the resourcefulness of astronomers and scientists and engineers overall. The two (or maybe three) remaining gyroscopes are of a new and upgraded design, designed to last five times as long as the original gyroscopes, which includes the one that recently failed. The James Webb Space Telescope, despite being billed as Hubble’s successor, is actually quite different, and will launch in 2021.
Even with one gyroscope, the Hubble Space Telescope should still be operational and capable of providing complementary observations to James Webb. This reduced-gyro mode has been planned for a long time. The only disappointment is that we may need to enter it so soon.”
One of the hallmarks of a successful NASA project is overengineering. Things will go wrong, break down, and degrade over time. One of the best examples is the Opportunity rover, which was designed for a 90 day mission and wound up living for nearly 15 years. But many people don’t appreciate how successfully overengineered Hubble is. Now well into its 28th year, it’s some 9 years removed from its final servicing mission. The gyroscopes that were installed included three of the old type and three of the new type, and the final old-style gyroscope has just failed.
Yet Hubble can continue operating and doing astronomy on just one gyroscope. Its demise has been greatly exaggerated; come learn the truth about Hubble today!
This Is Why Hubble Can’t See The Very First Galaxies
“By observing dark, empty patches of sky, it reveals ancient galaxies without nearby interference.
When distant galaxy clusters are present, these massive gravitational clumps behave as natural magnifying lenses.
The most distant observed galaxies have their light bent, distorted, and amplified along the journey.
Hubble discovered the current cosmic record-holder, GN-z11, via lensing.
Its light arrives from 407 million years after the Big Bang: 3% of the Universe’s current age.”
No astronomical observatory has revolutionized our view of the Universe quite like NASA’s Hubble Space Telescope. With the various servicing missions and instrument upgrades that have taken place over its lifetime, Hubble has pushed back the cosmic frontier of the first stars and galaxies to limits never before known. Yet there must be galaxies before them; some of the most distant Hubble galaxies have stars in them that push back the time of the first galaxies to just 250 million years after the Big Bang. Yet Hubble is physically incapable of seeing that far. Three factors: cosmic redshift, warm temperatures, and light-blocking gas, prevent us from going much beyond what we’ve already seen. In fact, we’re remarkably lucky to have gotten as distant as we have.
Find out why Hubble can’t see the very first galaxies, and why we need the James Webb space telescope!
First Stars Formed No Later Than 250 Million Years After The Big Bang, With Direct Proof
“We see MACS1149-JD1 as it was 530 million years after the Big Bang, while inside, it has a special signature: oxygen. Oxygen is only produced by previous generations of stars, indicating that this galaxy is already old.
MACS1149-JD1 was imaged with microwave (ALMA), infrared (Spitzer), and optical (Hubble) data combined.
The results indicate that stars existed nearly 300 million years before our observations.”
One of the great quests of astronomers today is to measure and locate the very first stars in the Universe. As far back as Hubble can see, to when the Universe was just 3-5% its current age, the Universe is still full of galaxies, even though they’re smaller and bluer than the ones we have today. But within these galaxies, we can also find evidence that the stars in there aren’t the very first ones; they contain evidence for prior generations of stars in their spectral signatures. From the second-most distant galaxy ever discovered, itself just 530 million years after the Big Bang, we see evolved stars. They indicate that the very first ones formed no later than 250 million years after the Big Bang.
The James Webb Space Telescope will be able to see that far! In less than 3 years, we’ll peer beyond where we’ve ever seen before. And there will no doubt be something breathtaking to look at.
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!