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You’re Always Surrounded by Neutrinos!

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.

I hope you’re all being gentle with yourself

isabelle mathers

Maria Thymann - Sophy A. Christensen (1867 - 1955) in her workshop (1899)

NASA Spotlight: Earth Climate Scientist Dr. Yolanda Shea

Dr. Yolanda Shea is a climate scientist at NASA's Langley Research Center. She’s the project scientist for the CLARREO Pathfinder (CPF) mission, which is an instrument that will launch to the International Space Station to measure sunlight reflected from Earth. It will help us understand how much heat is being trapped by our planet’s atmosphere. Her mission is designed to help us get a clearer picture than we currently have of the Earth’s system and how it is changing

Yolanda took time from studying our home planet to answer questions about her life and career! Get to know this Earth scientist:

What inspired you to study climate science?

Starting in early middle school I became interested in the explanations behind the weather maps and satellite images shown on TV. I liked how the meteorologists talked about the temperature, moisture, and winds at different heights in the atmosphere, and then put that together to form the story of our weather forecasts. This made me want to learn more about Earth science, so I went to college to explore this interest more.

The summer after my junior year of college, I had an internship during which my first assignment was to work with a program that estimated ocean currents from satellite measurements. I was fascinated in the fact that scientists had discovered a way to map ocean currents from space!

Although I had learned about Earth remote sensing in my classes, this was my first taste of working with, and understanding the details of, how we could learn more about different aspects of the physical world from satellite measurements.

This led to my learning about other ways we can learn about Earth from space, and that includes rigorous climate monitoring, which is the area I work in now.

What does a day in your life look like?

Before I start my workday, I like to take a few minutes to eat breakfast, knit (I’m loving sock knitting right now!), and listen to a podcast or audio book. Each workday really looks different for me, but regardless, most days are a combination of quieter moments that I can use for individual work and more interactive times when I’m interfacing with colleagues and talking about project or science issues. Both types of work are fun in different ways, but I’m glad I have a mixture because all researchers need that combination of deep thinking to wrap our minds around complex problems and also time to tackle those problems with others and work on solving them together.

When do you feel most connected to Earth?

I’ve always loved sunsets. I find them peaceful and beautiful, and I love how each one is unique. They are also a beautiful reminder of the versatility of reflected light, which I study. Sitting for a moment to appreciate the beauty and calm I feel during a sunset helps me feel connected to Earth.

What will your mission – CLARREO Pathfinder – tell us about Earth?

CLARREO Pathfinder (CPF) includes an instrument that will take measurements from the International Space Station and will measure reflected sunlight from Earth. One of its goals is to demonstrate that it can take measurements with high enough accuracy so that, if we have such measurements over long periods of time, like several decades, we could detect changes in Earth’s climate system. The CPF instrument will do this with higher accuracy than previous satellite instruments we’ve designed, and these measurements can be used to improve the accuracy of other satellite instruments.

How, if at all, has your worldview changed as a result of your work in climate science?

The longer I work in climate science and learn from the data about how humans have impacted our planet, the more I appreciate the fragility of our one and only home, and the more I want to take care of it.

What advice would you give your younger self?

It’s ok to not have everything figured out at every step of your career journey. Work hard, do your best, and enjoy the journey as it unfolds. You’ll inevitably have some surprises along the way, and regardless of whether they are welcome or not, you’re guaranteed to learn something.

Do you have a favorite metaphor or analogy that you use to describe what you do, and its impact, to those outside of the scientific community?

I see jigsaw puzzles as a good illustration of how different members of a science community play a diverse set of roles to work through different problems. Each member is often working on their own image within the greater puzzle, and although it might take them years of work to see their part of the picture come together, each image in the greater puzzle is essential to completing the whole thing. During my career, I’ll work on a section of the puzzle, and I hope to connect my section to others nearby, but we may not finish the whole puzzle. That’s ok, however, because we’ll hand over the work that we’ve accomplished to the next generation of scientists, and they will keep working to bring the picture to light. This is how I try to think about my role in climate science – I hope to contribute to the field in some way; the best thing about what I have done and what I will do, is that someone else will be able to build on my work and keep helping humanity come to a better understanding of our Earth system.

What is a course that you think should be part of required school curriculum?

Time and project management skills – I think students tend to learn these skills more organically from their parents and teachers, but in my experience I stumbled along and learned these skills through trial and error. To successfully balance all the different projects that I support now, I have to be organized and disciplined, and I need to have clear plans mapped out, so I have some idea of what’s coming and where my attention needs to be focused.

Another course not specifically related to my field is personal financial management. I was interested in personal finance, and that helped me to seek out information (mainly through various blogs) about how to be responsible with my home finances. There is a lot of information out there, but making sure that students have a solid foundation and know what questions to ask early on will set them to for success (and hopefully fewer mistakes) later on.

What’s the most unexpected time or place that your expertise in climate science and/or algorithms came in handy?

I think an interesting part of being an atmospheric scientist and a known sky-watcher is that I get to notice beautiful moments in the sky. I remember being on a trip with friends and I looked up (as I usually do), and I was gifted with a gorgeous sundog and halo arc. It was such a beautiful moment, and because I noticed it, my friends got to enjoy it too.

Can you share a photo or image from a memorable NASA project you’ve worked on, and tell us a little bit about why the project stood out to you?

I absolutely loved being on the PBS Kids TV Show, SciGirls for their episode SkyGirls! This featured a NASA program called Students’ Clouds Observations On-Line (S’COOL). It was a citizen science program where students from around the globe could take observations of clouds from the ground that coincided with satellite overpasses, and the intention was to help scientists validate (or check) the accuracy of the code they use to detect clouds from satellite measurements. I grew up watching educational programming from PBS, so it was an honor to be a science mentor on a TV show that I knew would reach children across the nation who might be interested in different STEM fields. In this photo, the three young women I worked with on the show and I are talking about the different types of clouds.

To stay up to date on Yolanda's mission and everything going on in NASA Earth science, be sure to follow NASA Earth on Twitter and Facebook.

🌎 If you're looking for Earth Day plans, we have live events, Q&As, scavenger hunts and more going on through April 24. Get the details and register for our events HERE.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.