This Is How We Know There Are Two Trillion Galaxies In The Universe
“Over time, galaxies merged together and grew, but small, faint galaxies still remain today. Even in our own Local Group, we’re still discovering galaxies that contain mere thousands of stars, and the number of galaxies we know of have increased to more than 70. The faintest, smallest, most distant galaxies of all are continuing to go undiscovered, but we know they must be there. For the first time, we can scientifically estimate how many galaxies are out there in the Universe.
The next step in the great cosmic puzzle is to find and characterize as many of them as possible, and understand how the Universe grew up. Led by the James Webb Space Telescope and the next generation of ground-based observatories, including LSST, GMT, and the ELT, we’re poised to reveal the hitherto unseen Universe as never before.”
How many galaxies are there in the Universe? If you had asked Carl Sagan a generation ago, the answer might have been something vague, like billions and billions. Just a decade or two ago, people would have guesstimated around 100 billion, as deep surveys from Hubble could give us a count of galaxies both near-and-far in a small region of the sky. But those estimates aren’t necessarily any good, except to serve as lower limits. In order to understand how many galaxies must truly be out there, it requires us to understand both what the Universe is made of and what constitutes a galaxy. Only in the last few years have we reached that level of sophistication, and come up with what we believe, for the first time, is an accurate number.
That number? Two trillion. There are two trillion galaxies in the Universe. This is the story of how we know.
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!
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!
Hubble: Andromeda Is Big, Massive, And Full Of The Stars Our Milky Way Is Missing
“The low-density, outer halo contains stars just as ancient as the Milky Way’s oldest: 13+ billion years of age. Andromeda has stellar streams populating that halo, with a third of those stars just 6-8 billion years old.
This means a major act of galactic cannibalism recently occurred.”
Every few years, a new study comes out claiming that the Milky Way may rival the Andromeda galaxy for the status of largest within our local group. Nonsense! Andromeda is practically double the diameter, contains anywhere from 2.5 to 5 times as many stars, and now there’s evidence that it gobbled up a number of massive galaxies relatively recently. Not only does it have stars just as old as the oldest we’ve ever found in the Milky Way, but we now have evidence that, 6-8 billion years ago, it devoured a large member of our local group entirely, with about a third of Andromeda’s halo stars having formed at around that time. When the Milky Way-Andromeda merger finally comes, there can be no doubt that the remnants of Andromeda will dominate whatever’s left.
Come see an astounding collection of images of our Local Group’s biggest, most massive galaxy, and get a window into what #1 in the Local Group looks like!
Hubble’s Latest Jaw-Dropper Shows Where The Universe’s Stars Come From
“Today, two trillion galaxies should exist within our observable Universe.
Most recently, Hubble released two new images of the ultra-deep, distant Universe.
These are the GOODS-North and GOODS-South fields, as viewed in ultraviolet light.
Ultraviolet light is special, because it shows us where the newest, youngest stars are right now.”
If you want to know where the newest stars in the Universe are, you have to look in ultraviolet light, which show us the hottest, bluest, and most massive stars. These stars live-and-die quickly, so wherever they show up, we know that star-formation must have occurred extremely recently, at least on cosmic timescales. The Hubble UV Ultra Deep Field, in 2014, demonstrated that we could learn how the Universe grew up. Now, with the GOODS-North and GOODS-South fields surveyed in ultraviolet, we can finally conclude when star formation peaked, and learn so much more than before about how the Universe grew up.
Don’t miss the spectacular picture show, and get the amazing science behind where the Universe’s stars come from!
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.
Hubble Catches New Stars, Individually, Forming In Galaxies Beyond The Milky Way
“There are a massive variety of star-forming regions nearby, and Hubble’s new Legacy ExtraGalactic UV Survey (LEGUS) is now the sharpest, most comprehensive one ever.
By imaging 50 nearby, star-forming spiral and dwarf galaxies, astronomers can see how the galactic environment affects star-formation.”
Within galaxies, new stars are going to be formed from the existing population of gas. But how that gas collapses and forms stars, as well as the types, numbers, and locations of the stars that will arise, is highly dependent on the galactic environment into which they are born. Dwarf galaxies, for example, tend to form stars when a nearby gravitational interaction triggers them. These bursts occur periodically, leading to multiple populations of stars of different ages. Spirals, on the other hand, form their new stars mostly along the lines traced by their arms, where the dust and gas is densest. Thanks to the Hubble Space Telescope, we’re capable of finding these stars and resolving them individually, using a combination of optical and ultraviolet data.
The best part? These are individually resolved stars from well outside our own galaxy: in 50 independent ones. Here’s what Hubble’s new LEGUS survey is revealing.
When Will We Break The Record For Most Distant Galaxy Ever Discovered?
“Finally, beyond a certain distance, the Universe hasn’t formed enough stars to reionize space and make it 100% transparent.
We only perceive galaxies in a few serendipitous directions, where copious star-formation occurred.
In 2016, we fortuitously discovered GN-z11 at a redshift of 11.1: from 13.4 billion years ago.
But recent, indirect evidence suggests stars formed at even greater redshifts and earlier times.“
It was only a couple of years ago that we set the current record for where the most distant galaxy is: from 13.4 billion years ago, when the Universe was just 3% its current age. This record is unlikely to be broken with our current set of observatories, as discovering a galaxy this distant required a whole bunch of unlikely, serendipitous phenomena to line up at once. But in 2020, the James Webb Space Telescope will launch: an observatory optimized for finding exactly the kinds of galaxy that push past the limits of what Hubble can do. We fully expect to not only break the record for most distant galaxy ever discovered, but to learn, for the first time, exactly where and when the first galaxies in the Universe truly formed.
Until then, it’s lots of fun to speculate as to when and where they might be, but it will take the observations of a lifetime to smash this cosmic record!
Hubble’s Greatest Discoveries Weren’t Planned; They Were Surprises
“And if we head out beyond our own galaxy, that’s where Hubble truly shines, having taught us more about the Universe than we ever imagined was out there. One of the greatest, most ambitious projects ever undertaken came in the mid-1990s, when astronomers in charge of Hubble redefined staring into the unknown. It was possibly the bravest thing ever done with the Hubble Space Telescope: to find a patch of sky with absolutely nothing in it — no bright stars, no nebulae, and no known galaxies — and observe it. Not just for a few minutes, or an hour, or even for a day. But orbit-after-orbit, for a huge amount of time, staring off into the nothingness of empty space, recording image after image of pure darkness.
What came back was amazing. Beyond what we could see, there were thousands upon thousand of galaxies out there in the abyss of space, in a tiny region of sky.”
28 years ago today, the Hubble Space Telescope was deployed. Since that time, it’s changed our view of the Solar System, the stars, nebulae, galaxies, and the entire Universe. But here’s the kicker: almost all of what it discovered wasn’t what it was designed to look for. We were able to learn so much from Hubble because it broke through the next frontier, looking at the Universe in a way we’ve never looked at it before. Astronomers and astrophysicists found clever ways to exploit its capabilities, and the observatory itself was overbuilt to the point where, 28 years later, it’s still one of the most sought-after telescopes as far as observing time goes.
Hubble’s greatest discoveries weren’t planned, but the planning we did enabled them to become real. Here are some great reasons to celebrate its anniversary.