This second, as you’re reading these words, trillions of tiny particles are hurtling toward you! No, you don’t need to brace yourself. They’re passing through you right now. And now. And now. These particles are called neutrinos, and they’re both everywhere in the cosmos and also extremely hard to find.
Neutrinos are fundamental particles, like electrons, so they can’t be broken down into smaller parts. They also outnumber all the atoms in the universe. (Atoms are made up of electrons, protons, and neutrons. Protons and neutrons are made of quarks … which maybe we’ll talk about another time.) The only thing that outnumbers neutrinos are all the light waves left over from the birth of the universe!
Credit: Photo courtesy of the Pauli Archive, CERN
Physicist Wolfgang Pauli proposed the existence of the neutrino, nearly a century ago. Enrico Fermi coined the name, which means “little neutral one” in Italian, because these particles have no electrical charge and nearly no mass.
Despite how many there are, neutrinos are really hard to study. They travel at almost the speed of light and rarely interact with other matter. Out of the universe’s four forces, ghostly neutrinos are only affected by gravity and the weak force. The weak force is about 10,000 times weaker than the electromagnetic force, which affects electrically charged particles. Because neutrinos carry no charge, move almost as fast as light, and don’t interact easily with other matter, they can escape some really bizarre and extreme places where even light might struggle getting out – like dying stars!
Through the weak force, neutrinos interact with other tiny fundamental particles: electrons, muons [mew-ons], and taus [rhymes with “ow”]. (These other particles are also really cool, but for right now, you just need to know that they’re there.) Scientists actually never detect neutrinos directly. Instead they find signals from these other particles. So they named the three types, or flavors, of neutrinos after them.
Neutrinos are made up of each of these three flavors, but cycle between them as they travel. Imagine going to the store to buy rocky road ice cream, which is made of chocolate ice cream, nuts, and marshmallows. When you get home, you find that it’s suddenly mostly marshmallows. Then in your bowl it’s mostly nuts. But when you take a bite, it’s just chocolate! That’s a little bit like what happens to neutrinos as they zoom through the cosmos.
Credit: CERN
On Earth, neutrinos are produced when unstable atoms decay, which happens in the planet’s core and nuclear reactors. (The first-ever neutrino detection happened in a nuclear reactor in 1955!) They’re also created by particle accelerators and high-speed particle collisions in the atmosphere. (Also, interestingly, the potassium in a banana emits neutrinos – but no worries, bananas are perfectly safe to eat!)
Most of the neutrinos around Earth come from the Sun – about 65 billion every second for every square centimeter. These are produced in the Sun’s core where the immense pressure squeezes together hydrogen to produce helium. This process, called nuclear fusion, creates the energy that makes the Sun shine, as well as neutrinos.
The first neutrinos scientists detected from outside the Milky Way were from SN 1987A, a supernova that occurred only 168,000 light-years away in a neighboring galaxy called the Large Magellanic Cloud. (That makes it one of the closest supernovae scientists have observed.) The light from this explosion reached us in 1987, so it was the first supernova modern astronomers were able to study in detail. The neutrinos actually arrived a few hours before the light from the explosion because of the forces we talked about earlier. The particles escape the star’s core before any of the other effects of the collapse ripple to the surface. Then they travel in pretty much a straight line – all because they don’t interact with other matter very much.
Credit: Martin Wolf, IceCube/NSF
How do we detect particles that are so tiny and fast – especially when they rarely interact with other matter? Well, the National Science Foundation decided to bury a bunch of detectors in a cubic kilometer of Antarctic ice to create the IceCube Neutrino Observatory. The neutrinos interact with other particles in the ice through the weak force and turn into muons, electrons, and taus. The new particles gain the neutrinos’ speed and actually travel faster than light in the ice, which produces a particular kind of radiation IceCube can detect. (Although they would still be slower than light in the vacuum of space.)
In 2013, IceCube first detected high-energy neutrinos, which have energies up to 1,000 times greater than those produced by Earth’s most powerful particle collider. But scientists were puzzled about where exactly these particles came from. Then, in 2017, IceCube detected a high-energy neutrino from a monster black hole powering a high-speed particle jet at a galaxy’s center billions of light-years away. It was accompanied by a flash of gamma rays, the highest energy form of light.
But particle jets aren’t the only place we can find these particles. Scientists recently announced that another high-energy neutrino came from a black hole shredding an unlucky star that strayed too close. The event didn’t produce the neutrino when or how scientists expected, though, so they’ve still got a lot to learn about these mysterious particles!
Keep up with other exciting announcements about our universe by following NASA Universe on Twitter and Facebook.
Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.
Nicolas Geiser - Almost, 2015, stylo sur papier, 29,7 x 21 cm
I hope you’re all being gentle with yourself
sometimes losing people makes u find urself
I got the chance to road trip out to the path of totality! My phone camera didn’t do it justice, so I painted what I saw instead 🌞🌚
Here’s the photo I took and the sketch I made with my finger in the notes app while watching it happen 😆
sillygirlcarmen Friday Feels “12:22″ 15 minute mix
follow on instagram @sillygirlcarmen
Black holes are some of the most bizarre and fascinating objects in the cosmos. Astronomers want to study lots of them, but there’s one big problem – black holes are invisible! Since they don’t emit any light, it’s pretty tough to find them lurking in the inky void of space. Fortunately there are a few different ways we can “see” black holes indirectly by watching how they affect their surroundings.
If you’ve spent some time stargazing, you know what a calm, peaceful place our universe can be. But did you know that a monster is hiding right in the heart of our Milky Way galaxy? Astronomers noticed stars zipping superfast around something we can’t see at the center of the galaxy, about 10 million miles per hour! The stars must be circling a supermassive black hole. No other object would have strong enough gravity to keep them from flying off into space.
Two astrophysicists won half of the Nobel Prize in Physics last year for revealing this dark secret. The black hole is truly monstrous, weighing about four million times as much as our Sun! And it seems our home galaxy is no exception – our Hubble Space Telescope has revealed that the hubs of most galaxies contain supermassive black holes.
Technology has advanced enough that we’ve been able to spot one of these supermassive black holes in a nearby galaxy. In 2019, astronomers took the first-ever picture of a black hole in a galaxy called M87, which is about 55 million light-years away. They used an international network of radio telescopes called the Event Horizon Telescope.
In the image, we can see some light from hot gas surrounding a dark shape. While we still can’t see the black hole itself, we can see the “shadow” it casts on the bright backdrop.
Black holes can come in a smaller variety, too. When a massive star runs out of the fuel it uses to shine, it collapses in on itself. These lightweight or “stellar-mass” black holes are only about 5-20 times as massive as the Sun. They’re scattered throughout the galaxy in the same places where we find stars, since that’s how they began their lives. Some of them started out with a companion star, and so far that’s been our best clue to find them.
Some black holes steal material from their companion star. As the material falls onto the black hole, it gets superhot and lights up in X-rays. The first confirmed black hole astronomers discovered, called Cygnus X-1, was found this way.
If a star comes too close to a supermassive black hole, the effect is even more dramatic! Instead of just siphoning material from the star like a smaller black hole would do, a supermassive black hole will completely tear the star apart into a stream of gas. This is called a tidal disruption event.
But what if two companion stars both turn into black holes? They may eventually collide with each other to form a larger black hole, sending ripples through space-time – the fabric of the cosmos!
These ripples, called gravitational waves, travel across space at the speed of light. The waves that reach us are extremely weak because space-time is really stiff.
Three scientists received the 2017 Nobel Prize in Physics for using LIGO to observe gravitational waves that were sent out from colliding stellar-mass black holes. Though gravitational waves are hard to detect, they offer a way to find black holes without having to see any light.
We’re teaming up with the European Space Agency for a mission called LISA, which stands for Laser Interferometer Space Antenna. When it launches in the 2030s, it will detect gravitational waves from merging supermassive black holes – a likely sign of colliding galaxies!
So we have a few ways to find black holes by seeing stuff that’s close to them. But astronomers think there could be 100 million black holes roaming the galaxy solo. Fortunately, our Nancy Grace Roman Space Telescope will provide a way to “see” these isolated black holes, too.
Roman will find solitary black holes when they pass in front of more distant stars from our vantage point. The black hole’s gravity will warp the starlight in ways that reveal its presence. In some cases we can figure out a black hole’s mass and distance this way, and even estimate how fast it’s moving through the galaxy.
For more about black holes, check out these Tumblr posts!
⚫ Gobble Up These Black (Hole) Friday Deals!
⚫ Hubble’s 5 Weirdest Black Hole Discoveries
Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.
What a truly mind blowing thing you’ve turned The Eras Tour Concert Film into. I’ve been watching videos of you guys in the theaters dancing and prancing and recreating choreography, creating inside jokes, casting spells, getting engaged, and just generally creating the exact type of joyful chaos we’re known for 😇 One of my favorite things you’ve done was when you supported Cruel Summer SO much, I ended up starting The Eras Tour show with it. For old times sake, I’m releasing the live audio from the tour so we can all shriek it in the comfort of our homes and cars PLUS a brand new remix by LP Giobbi 😜 Thank you, so much, forever, wow, just thank you!!! https://taylor.lnk.to/thecruelestsummer
The Secretary-General's son Gabriel Lougou Unicef.org 🇺🇳🇨🇫🇩🇰.
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