This Is How Astronomy Is Finally Defeating Its Greatest Enemy: Earth’s Atmosphere
“This is not only a tremendous boon to astronomy, but represents the potential of successful collaborations between government-funded endeavors and private industry. Without the participation of both, improvements such as these would have been impossible. With 25-to-39 meter class telescopes scheduled to come online in the coming decade, including the future ELT at 39 meters and also managed by ESO, it’s never been a better time to be a ground-based astronomer.
For decades, the only ways to contend with the atmosphere were either to live with it or to go above it. Yet over the past few years, all of that is changing. It’s time to seriously consider outfitting all of our large observatories with adaptive optics systems like this. If these improvements continue, ground-based astronomy may be able to surpass space-based telescopes, as far as quality-imaging-per-dollar goes, once and for all!”
So, you want to view the Universe as accurately as possible, but you don’t have the ability to put your dream observatory in space? Welcome to the world of astronomy, where there’s a trade-off between what you can do from the ground (where weight and size are no concern) and what you can do from space (where you don’t have an atmosphere). The Hubble Space Telescope has been so revolutionary because of all that it could see without any atmospheric interference, but the ground is catching up. The science of adaptive optics is progressing tremendously as the years go by, enabling us to compensate for the atmosphere and. in some cases, to even defeat Hubble with telescopes here on Earth.
At last, astronomers are finally defeating their true observational nemesis: Earth’s atmosphere. This is the story of how.
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!
Your 2017 Gift Guide For The Physics And Astronomy Lover In Your Life
“Best book on gravitational waves: Ripples In Spacetime, by Govert Schilling. Scientifically, there are few things more compelling than a brand new discovery that revolutionizes our conception of the Universe. Einstein’s theory of General Relativity brought forth with it a new theory of space and time, complete with a new form of radiation: gravitational waves. 100 years, a number of theoretical battles, and a colossal experimental achievement later, we’ve finally reached the era of gravitational wave astronomy. Govert’s blend of storytelling, interviews, science, and history creates a fantastic read, and for anyone curious about the development of LIGO and what the future holds, you couldn’t as for a better story.”
Well, it’s the holiday season, and many of you are wondering what the best books (and more) are for physics and astronomy aficionados out there. Here are ten items hand-picked by me, an astrophysicist, that highlight the best of what this year has to offer. (Okay, two books came out at the very end of last year, but they still count!) From biographies to cosmic stories, from Earth and our place in it to the scale and fine-tuning of the entire Universe, and from Star Trek to actually viewing the stars with your own star-filled eyes, there should be something (affordable!) here for everyone.
Come get your 2017 gift guide for the physics and astronomy lover in your life, and note, you can pick up everything on this list for right around $320!
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 don’t we build a telescope without mirrors or lenses?
“Why do we need a lens and a mirror to make a telescope now that we have CCD sensors? Instead of having a 10m mirror and lens that focus the light on a small sensor, why not have a 10m sensor instead?”
Every time you shine light through a lens or reflect it off of a mirror, no matter how good it is, a portion of your light gets lost. Today’s largest, most powerful telescopes don’t even simply have a primary mirror, but secondary, tertiary, even quaternary or higher mirrors, and each of those reflections means less light to derive your data from. As CCDs and other digital devices are far more efficient than anything else, why couldn’t we simply replace the primary mirror with a CCD array to collect and measure the light? It seems like a brilliant idea on the surface, and it would, in fact, gather significantly more light over the same collecting area. True, CCDs are more expensive, and there are technical challenges as far as applying filters and aligning the array properly. But there’s a fundamental problem if you don’t use a mirror or lens at all that may turn out to be a dealbreaker: CCDs without lenses or mirrors are incapable of measuring the direction light is coming from. A star or galaxy would appear equally on all portions of your CCD array at once, giving you just a bright, white-light image on every single CCD pixel.
It’s a remarkable idea, but there’s a good physical reason why it won’t pan out. For the foreseeable future, we still need optics to make a telescope! Find out why on this week’s Ask Ethan.
New Space Telescope, 40 Times The Power Of Hubble, To Unlock Astronomy’s Future
“But these potential discoveries are what we know we’re going to be looking for. With every new major technological leap forward we’ve ever taken in astronomy and astrophysics, the greatest achievements of all have been the ones we could not have anticipated in advance. The great unknowns of the Universe, including what it looks like in the faintest regimes, how the most distant stars, galaxies, gas clouds, and the intergalactic medium behaved at early times, and what it looks like beyond anything we’ve ever seen will all be exposed for the first time. It’s possible that we’ll learn we were quite arrogant and wrongheaded in a great multitude of arenas, but we’ll need this new, high-quality data to show us the way.”
If you were an observational astronomer, what would your dream telescope look like? It would have to be huge, with an incredible amount of light-gathering power. The quality of the optics would have to be pristine, and higher-precision than anything ever created before. It would have to have multispectral capabilities, extending beyond both sides of the visible light spectrum. And it would have to be in space, with no interference from our atmosphere. If we could build a telescope like that, so many things would immediately become possible. We’d be able to directly image perhaps 100 exo-Earths around nearby stars, including spectra of their atmospheres. We’d take images of Jupiter of the same quality that JUNO can, but from Earth’s orbit. We’d be able to measure the star clusters inside and gas halos surrounding every galaxy in the Universe to just a few hundred light year-precision. And we’d be able to take high-resolution images of the faintest, most distant galaxies of all, in just a tiny fraction of the time it’s taken Hubble to do it.
There’s a 15.1-meter space telescope that’s in design right now: LUVOIR. If everything goes well, it could be NASA’s flagship mission of the 2030s. Want to learn more? Here’s what it’s all about!
A New Record Nears: The World’s Largest Telescope Prepares For Completion
“The ELT, by the nature of its size, its power, its weight, and its complexity, could never have been a “build-it-and-you’re-done” type of telescope. It needs to be continuously adjusted throughout the night to maintain the optimal mirror shape; it needs to be re-calibrated night-to-night to achieve that perfect set point; it needs to have its mirrors recoated every 18 months to keep that ideal 7.5 nanometer smoothness. But if you do all of that, and you use the ideal techniques and instruments — from pointing-and-tracking to adaptive optics to imaging methodology — the ELT has the capability to outclass every other optical telescope ever built, on Earth or in space. It’s going to be an incredible technical achievement when complete, an achievement that requires continuous work to maintain. But the science we’ll get from it will be unlike anything else our world has ever seen.”
Throughout history, a number of advances have enabled astronomers to collect superior data about the Universe. Smoother mirrors, adaptive optics, superior instrumentation, and optimized photon collection have all made significant contributions, but at some point, you simply have no choice but to go bigger. Doubling the size of your primary mirror doubles your resolution and quadruples your light-gathering power, so bigger is always better. In the mid-2020s, the Extremely Large Telescope (ELT) will be completed, surpassing everything. At 39 meters in diameter, the ELT will be made up of 798 hexagonal segments, each one an impressive 1.4 meters from corner-to-corner. The smoothness of the surface will be a ridiculous 7.5 nanometers, with a resolving power capable of scientific advances the world has never seen. But just as impressive is the technical achievement of making, assembling, and configuring the mirrors. To make the largest, most accurate telescope the world has ever seen means creating something with unprecedented precision.
Here’s a look at the inner workings of the world’s (future) largest telescope!
5 Facts We Can Learn If LIGO Detects Merging Neutron Stars
“We have already entered a new age in astronomy, where we’re not just using telescopes, but interferometers. We’re not just using light, but gravitational waves, to view and understand the Universe. If merging neutron stars reveal themselves to LIGO, even if the events are rare and the detection rate is low, it’s means we’ll have crossed that next frontier. The gravitational sky and the light-based sky will no longer be strangers to one another. Instead, we’ll be one step closer to understanding how the most extreme objects in the Universe actually work, and we’ll have a window into our cosmos that no human has ever had before.”
Two years ago, advanced LIGO turned on, and in that brief time, it’s already revealed a number of gravitational wave events. All of them, to no one’s surprise, have been merging black holes, since those are the easiest class of events for LIGO to detect. But beyond black holes, LIGO should also be sensitive to merging neutron stars. Even though the range over which LIGO can see them is much smaller, if there are enough neutron star-neutron star mergers happening, we might have a chance. A little over a week ago, a rumor broke that LIGO may have seen one, which would be a phenomenal occurrence. Not only would we have a new type of event that we detected in gravitational waves, we would, for the first time, have the capability of correlating the gravitational and electromagnetic skies. Astronomy, for the first time ever, could view the very same object in gravitational waves and through telescopes.
This is a big deal, and there are four more facts we’ll learn if LIGO sees it! Come find out what they are!
Ask Ethan: Why can’t I see Mercury without a telescope?
“I have been sitting on the coast watching the sun set through the thinnest sliver of clear sky on the horizon. I’m struggling with a question: how can one see Mercury with the naked eye? I know it’s possible, but how can I observe it enough to know it’s a “wandering star”? It’s the only classical planet I’ve never seen. Help!”
Under ideal conditions, Mercury achieves a maximum elongation, or angular separation, from the Sun of 28 degrees. Total darkness is achieved when the Sun dips 18 degrees below the horizon. So for many of us, why is it that we’ve never been able to see the closest planet to the Sun, even when it appears we have ideal conditions? As you may have guessed, there’s more to the equation than that. A huge factor is your latitude, and what angle the Sun rises/sets at with respect to the horizon. If you live closer to one of the poles than the equator, there’s a good chance that you’ll never be able to see Mercury, even at this maximum, ideal elongation, as by time darkness sets in, the world is well below the horizon.
Still, even with that at play, you can still have a chance if you know where/when to look! Find out the tricks on this week’s Ask Ethan!