What Was It Like When Starlight First Broke Through The Universe’s Neutral Atoms?
“The light created in the earliest era of stars and galaxies all plays a role. The ultraviolet light works to ionize the matter around it, enabling visible light to progressively farther and farther as the ionization fraction increases. The visible light gets scattered in all directions until reionization has gotten far enough to enable our best telescopes today to see it. But the infrared light, also created by the stars, passes through even the neutral matter, giving our 2020s-era telescopes a chance to find them.
When starlight breaks through the sea of neutral atoms, even before reionization completes, it gives us a chance to detect the earliest objects we’ll ever have seen. When the James Webb Space Telescope launches, that will be the first thing we look for. The most distant reaches of the Universe are within our view. We just have to look and find out what’s truly out there.”
Something existing in our Universe is not quite the same as something being detectable in our Universe. We know that, at some point in our past, we created the first generation of stars, the second generation of stars, and the very first galaxies to exist in our Universe. But in order to detect them, there has to be some way for that light to travel through the Universe to our observatories and telescopes monitoring the skies today. There’s an obstacle standing in the way of that, though: the neutral atoms formed just hundreds of thousands of years after the Big Bang. When the first hints of starlight begin permeating through space, they encounter these neutral atoms, which largely thwarts them. It takes hundreds of millions of years for starlight to win.
But with enough persistence and star-formation, the light will eventually break through. Come get the cosmic story of how this all actually happens!
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!
These Are The Most Distant Objects We’ve Ever Discovered In The Universe
“For planets of any type, the quasar RX J1131-1231, lensed by rogue planets, holds the record: 3.9 billion light-years distant. The most distant normal star is known as Icarus, 9 billion light-years away, lensed and magnified by a massive galaxy cluster. 23 billion light-years away is the most distant supernova ever seen: SN 1000+0216.”
Our quest to learn about the Universe is a quest of ever-receding horizons. From planets, moons, and other objects in our Solar System to stars, galaxies, quasars, and gamma-ray bursts, we just keep shattering records as far distance goes. Improvements in technology, technique, and increased observing time allow us to reveal things that simply couldn’t be observed previously. Yet we’re by no means done, just because we’ve set a slew of new records in the opening two decades of the 21st century. With the launch of the James Webb Space Telescope, the hope of a Planet Nine, and the advent of 30-meter-class astronomy from the ground, the records we know and adore today may all be in the rear-view mirror just a few years from now.
What are the most distant objects of all different types in the Universe? Get the 2018 update right now!
The Universe Has A Speed Limit, And It Isn’t The Speed Of Light
“We believe that every charged particle in the cosmos — every cosmic ray, every proton, every atomic nucleus — should limited by this speed. Not just the speed of light, but a little bit lower, thanks to the leftover glow from the Big Bang and the particles in the intergalactic medium. If we see anything that’s at a higher energy, then it either means:
1. particles at high energies might be playing by different rules than the ones we presently think they do,
2. they are being produced much closer than we think they are: within our own Local Group or Milky Way, rather than these distant, extragalactic black holes,
3. or they’re not protons at all, but composite nuclei.”
If you were to try and travel as close to the speed of light as possible, you’d never get there because of Einstein’s relativity and the fact that you have mass. But even if you pumped an arbitrary amount of energy into you, you still wouldn’t get arbitrarily close to the speed of light. Instead, you’d find that there was a barrier or cutoff just a little bit below the speed of light: about 80 femtometers-per-second below the ultimate cosmic speed limit. That’s because the leftover glow from the Big Bang, the cosmic microwave background, exists no matter where you go, and prevents you from going any faster. Even if you beat that speed, it will knock you back down below it in short order.
There’s a speed limit for matter in the Universe, and it isn’t the speed of light. Come find out the details of why today!
For The Last Time: The LHC Will Not Make An Earth-Swallowing Black Hole
“To prevent decay, new, unknown physics — for which no evidence exists — must be invoked.
Even if the newly created black hole were stable, it could not devour the Earth. The maximum rate it could consume matter is 1.1 × 10-25 grams-per-second.
It would take 3 trillion years to grow to a mass of 1 kg.”
Well, it was only a matter of time before someone trotted out the long-debunked claim that the LHC could possibly create an Earth-destroying black hole. I, like most of you, just didn’t expect that person to be the esteemed astronomer Sir Martin Rees!
Well, you’ll be happy to know that not only is his claim untrue, but it’s very easy to demonstrate why. You don’t have to point to cosmic rays (which are more energetic and have struck Earth for billions of years) or rely on anything we haven’t already directly observed. In fact, we can even imagine exotic scenarios that could result in the creation of a black hole, and even then, the Earth is entirely safe.
In less than 200 words, you, too, can learn why the LHC will not make an Earth-swallowing black hole. Sorry, all you armchair supervillains out there.
The Most Important X-Ray Image Ever Taken Proved The Existence Of Dark Matter
“Yet the most important X-ray image of all time was an incredible surprise. This is the Bullet Cluster: a system of two galaxy clusters colliding at high speeds. As the gaseous matter inside collides, it slows, heats up, and lags behind, emitting X-rays. However, we can use gravitational lensing to learn where the mass is located in this system. he bending and shearing of light from background galaxies shows it’s separated from the matter’s and X-rays’ location. This separation is some of our strongest evidence for dark matter.”
There are many different lines of evidence for dark matter, but one of the biggest contentions of those who disbelieve it is that a direct empirical proof of its existence is needed. If it exists in a large, diffuse halo around every galaxy, cluster, and component of large-scale structure in the Universe, you should be able to prove it. Starting more than 10 years ago, astronomers have been able to do just that. When galaxy clusters collide, the overwhelming majority of normal matter, residing in the intracluster medium, should smash together, heat up, and emit X-rays. It does! But the biggest deal is that the gravitational mass, reconstructed through lensing, doesn’t coincide with the normal matter.
There must be some other type of matter from the normal, baryonic matter. Ergo, dark matter. Here’s (IMO) the most important X-ray story of all-time.
What Was It Like When The Universe Made Its Second Generation Of Stars?
“The very first stars live only an extremely short time, owing to their high masses and large luminosities and rates-of-fusion. When they die, the space around them becomes polluted with the fruits of their lives: heavy elements. These heavy elements enable the second generation of stars to form, but they now form differently. The heavy elements radiate heat away, giving rise to a less massive, more diverse generation of stars, some of which survive even to the present day.
When the James Webb Space Telescope begins operations, it may yet reveal a population of these first stars, likely to be found alongside polluted, second-generation stars. But once these second-generation stars begin to form, they make something else possible: the first galaxies. And that, in just a few years, is likely where the James Webb Space Telescope will truly shine.”
The first stars in the Universe, as astronomers define them, are stars made out of pristine materials left over from the Big Bang: almost exclusively hydrogen and helium. Because of this, their options are limited. They’re all very massive, they have no rocky planets around them, they live a short time, and they almost all die in a supernova. That’s not a life-friendly environment! But all of that changes with the second generation of stars, which forms just a few million years after the first. Some of these may even survive in the Milky Way to the present day… and we might have even found them already.
Come learn what the Universe was like when it form the second generation of stars, and why this is so important in our own cosmic story!
We Know Almost Nothing About Proxima b, The Closest Exoplanet To Earth
“In reality, we do not even know whether this planet is Earth-like or Neptune-like. The typical border between an Earth-like world, where you have a rocky surface with a thin atmosphere, and a Neptune-like world, where you have a large gas envelope surrounding your world, is about 2 Earth masses. Proxima b has a minimum mass of about 1.3 Earths, but that’s if the alignment is perfectly edge-on. Since there’s no transit, we know the alignment cannot be exactly perfect, but how imperfect is it? That’s gloriously unknown.
If the alignment is inclined at more than about 25° from our line-of-sight, it’s likely to be a gaseous world, not a rocky, Earth-like one. But at this point, without further information, we cannot know.”
Two years ago, some amazing news came in from the astronomical world: the closest star beyond our Sun, Proxima Centauri, has a planet orbiting it. Named Proxima b, it has an orbital period of 11.2 days around a star just 0.17% as luminous as our Sun. This places it into what we call the habitable zone, as it receives approximately 65% of the energy that Earth receives from the Sun. It also has a mass that’s touted as 1.3 times the mass of Earth, but that figure is very suspect. We can claim that as the minimum mass, but can do no better than that. As far as life, water, oceans, or even an atmosphere goes, we have no idea. It could be a completely airless, barren world, or could have a thick gas envelope like Neptune.
Without more and better data, we simply cannot know. We know very little about Proxima b. Here’s how you can separate scientific fact from mere speculation.
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!
This Is Why Scientists Think Planet Nine Doesn’t Exist
“Of course, this study isn’t enough to rule out Planet Nine; it still could be out there. As a counterpoint, Mike Brown has contended that a different survey strategy could have been definitive, and OSSOS simply isn’t a good survey for indicating yea or nay on Planet Nine. But remember, the old saying goes, “where there’s smoke, there’s fire,” indicating that if you observe an effect, it likely has a cause.
If you all of a sudden discover that what you thought was smoke was a figment of your imagination, it doesn’t mean there wasn’t a fire, but it sure does make the hypothesis that there ever was a fire a lot less compelling. The OSSOS study doesn’t rule out Planet Nine, but it does cast doubt on the idea that the Solar System needs one. Unless a deeper, better survey indicates otherwise, or Planet Nine serendipitously turns up, the default position should be its non-existence.”
Is there another massive planet in the Solar System? Do we have a super-Earth after all, between the masses and sizes of Earth and Neptune? And has it only gone undiscovered until now owing to our telescopic limitations, and the fact that it’s so much more distant than the presently known planets?
It’s possible. That’s the radical idea behind Planet Nine, proposed nearly three years ago by Konstantin Batygin and Mike Brown. They looked at the unusual orbits of a number of Kuiper Belt objects, and conjectures that a ninth planet, located hundreds of times as distant as Earth is from the Sun, could be the culprit. But on closer inspection, the evidence that they’re looking at might just be biased, and there may be no Planet Nine at all.
There may not even be a puzzle to solve. Come get the scientific story on Planet Nine that you haven’t heard today.