Outer Space - Blog Posts

Seeing the Invisible Universe

This computer-simulated image shows a supermassive black hole at the core of a galaxy. The black region in the center represents the black hole’s event horizon, beyond which no light can escape the massive object’s gravitational grip. The black hole’s powerful gravity distorts space around it like a funhouse mirror. Light from background stars is stretched and smeared as it skims by the black hole. You might wonder — if this Tumblr post is about invisible things, what’s with all the pictures? Even though we can’t see these things with our eyes or even our telescopes, we can still learn about them by studying how they affect their surroundings. Then, we can use what we know to make visualizations that represent our understanding.

When you think of the invisible, you might first picture something fantastical like a magic Ring or Wonder Woman’s airplane, but invisible things surround us every day. Read on to learn about seven of our favorite invisible things in the universe!

1. Black Holes

This animation illustrates what happens when an unlucky star strays too close to a monster black hole. Gravitational forces create intense tides that break the star apart into a stream of gas. The trailing part of the stream escapes the system, while the leading part swings back around, surrounding the black hole with a disk of debris. A powerful jet can also form. This cataclysmic phenomenon is called a tidal disruption event.

You know ‘em, and we love ‘em. Black holes are balls of matter packed so tight that their gravity allows nothing — not even light — to escape. Most black holes form when heavy stars collapse under their own weight, crushing their mass to a theoretical singular point of infinite density.

Although they don’t reflect or emit light, we know black holes exist because they influence the environment around them — like tugging on star orbits. Black holes distort space-time, warping the path light travels through, so scientists can also identify black holes by noticing tiny changes in star brightness or position.

2. Dark Matter

A simulation of dark matter forming large-scale structure due to gravity.

What do you call something that doesn’t interact with light, has a gravitational pull, and outnumbers all the visible stuff in the universe by five times? Scientists went with “dark matter,” and they think it's the backbone of our universe’s large-scale structure. We don’t know what dark matter is — we just know it's nothing we already understand.

We know about dark matter because of its gravitational effects on galaxies and galaxy clusters — observations of how they move tell us there must be something there that we can’t see. Like black holes, we can also see light bend as dark matter’s mass warps space-time.

3. Dark Energy

Animation showing a graph of the universe’s expansion over time. While cosmic expansion slowed following the end of inflation, it began picking up the pace around 5 billion years ago. Scientists still aren’t sure why.

No one knows what dark energy is either — just that it’s pushing our universe to expand faster and faster. Some potential theories include an ever-present energy, a defect in the universe’s fabric, or a flaw in our understanding of gravity.

Scientists previously thought that all the universe’s mass would gravitationally attract, slowing its expansion over time. But when they noticed distant galaxies moving away from us faster than expected, researchers knew something was beating gravity on cosmic scales. After further investigation, scientists found traces of dark energy’s influence everywhere — from large-scale structure to the background radiation that permeates the universe.

4. Gravitational Waves

Two black holes orbit each other and generate space-time ripples called gravitational waves in this animation.

Like the ripples in a pond, the most extreme events in the universe — such as black hole mergers — send waves through the fabric of space-time. All moving masses can create gravitational waves, but they are usually so small and weak that we can only detect those caused by massive collisions.  Even then they only cause infinitesimal changes in space-time by the time they reach us. Scientists use lasers, like the ground-based LIGO (Laser Interferometer Gravitational-Wave Observatory) to detect this precise change. They also watch pulsar timing, like cosmic clocks, to catch tiny timing differences caused by gravitational waves.

This animation shows gamma rays (magenta), the most energetic form of light, and elusive particles called neutrinos (gray) formed in the jet of an active galaxy far, far away. The emission traveled for about 4 billion years before reaching Earth. On Sept. 22, 2017, the IceCube Neutrino Observatory at the South Pole detected the arrival of a single high-energy neutrino. NASA’s Fermi Gamma-ray Space Telescope showed that the source was a black-hole-powered galaxy named TXS 0506+056, which at the time of the detection was producing the strongest gamma-ray activity Fermi had seen from it in a decade of observations.

5. Neutrinos

This animation shows gamma rays (magenta), the most energetic form of light, and elusive particles called neutrinos (gray) formed in the jet of an active galaxy far, far away. The emission traveled for about 4 billion years before reaching Earth. On Sept. 22, 2017, the IceCube Neutrino Observatory at the South Pole detected the arrival of a single high-energy neutrino. NASA’s Fermi Gamma-ray Space Telescope showed that the source was a black-hole-powered galaxy named TXS 0506+056, which at the time of the detection was producing the strongest gamma-ray activity Fermi had seen from it in a decade of observations.

Because only gravity and the weak force affect neutrinos, they don’t easily interact with other matter — hundreds of trillions of these tiny, uncharged particles pass through you every second! Neutrinos come from unstable atom decay all around us, from nuclear reactions in the Sun to exploding stars, black holes, and even bananas.

Scientists theoretically predicted neutrinos, but we know they actually exist because, like black holes, they sometimes influence their surroundings. The National Science Foundation’s IceCube Neutrino Observatory detects when neutrinos interact with other subatomic particles in ice via the weak force.

6. Cosmic Rays

This animation illustrates cosmic ray particles striking Earth's atmosphere and creating showers of particles.

Every day, trillions of cosmic rays pelt Earth’s atmosphere, careening in at nearly light-speed — mostly from outside our solar system. Magnetic fields knock these tiny charged particles around space until we can hardly tell where they came from, but we think high energy events like supernovae can accelerate them. Earth’s atmosphere and magnetic field protect us from cosmic rays, meaning few actually make it to the ground.

Though we don’t see the cosmic rays that make it to the ground, they tamper with equipment, showing up as radiation or as “bright” dots that come and go between pictures on some digital cameras. Cosmic rays can harm astronauts in space, so there are plenty of precautions to protect and monitor them.

7. (Most) Electromagnetic Radiation

The electromagnetic spectrum is the name we use when we talk about different types of light as a group. The parts of the electromagnetic spectrum, arranged from highest to lowest energy are: gamma rays, X-rays, ultraviolet light, visible light, infrared light, microwaves, and radio waves. All the parts of the electromagnetic spectrum are the same thing — radiation. Radiation is made up of a stream of photons — particles without mass that move in a wave pattern all at the same speed, the speed of light. Each photon contains a certain amount of energy.

The light that we see is a small slice of the electromagnetic spectrum, which spans many wavelengths. We frequently use different wavelengths of light — from radios to airport security scanners and telescopes.

Visible light makes it possible for many of us to perceive the universe every day, but this range of light is just 0.0035 percent of the entire spectrum. With this in mind, it seems that we live in a universe that’s more invisible than not! NASA missions like NASA's Fermi, James Webb, and Nancy Grace Roman  space telescopes will continue to uncloak the cosmos and answer some of science’s most mysterious questions.

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The stunning Veil Nebula was created after a star about 20 times the mass of the Sun lived fast and died young – exploding in a cataclysmic release of energy known as a supernova.

In a violent stellar explosion roughly 10,000 years ago, shockwaves and debris created this staggeringly beautiful trail through space. The picture above shows a mosaic of six Hubble Space Telescope pictures, a small area roughly two light-years across, and only a tiny fraction of the nebula's vast 110 light-year structure.

To learn more about Hubble’s celebration of Nebula November and see new nebula images, visit our space telescope's nebula page.

You can also keep up with Hubble on Twitter, Instagram, Facebook, and Flickr!

Image credits: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

The Exploration Behind the Inspiration at NASA

Are we alone? How did we get here? Where are we headed?

At NASA, our mission is to explore. We visit destinations in our solar system and study worlds beyond to better understand these big questions.

We also dream. We dream of traveling to distant worlds, and what that might be like. In the video above you can see fanciful, imagined adventures to real places we’ve studied at NASA.

How We Did It

Check out how we created these otherworldly scenes in the video below. A NASA videographer used green screens to add motion and real people to bring life to our series of solar system and exoplanet travel posters.

Let’s dive into one example from the video. The shot of kayaking on Titan showcases the real rivers and lakes of liquid methane and ethane that slosh and flow on Saturn's largest moon. Titan's mysterious surface was revealed by our Cassini spacecraft, which also deployed the European Space Agency’s Huygens probe to the surface. The atmosphere on Titan is so thick, and the gravity so light, that with each strike of a paddle, you might be lofted above the swift current as you ride the tides through a narrow strait called the Throat of Kraken. NASA scientist Mike Malaska studies Titan and collaborated on the poster featured in the video. His research informed the artwork, and so did a hobby: kayaking. Those ultra-cold chemical seas might be even more of a challenge than shown here. Your boat might crack, or even dissolve, Malaska said.

We’ll learn more about Titan when our Dragonfly mission of dual quadcoptors — rotorcraft with eight blades each — visits the icy moon in 2034.

Science Never Stops

Our understanding of other worlds is always evolving, and sometimes we learn new details after we illustrate our science. In one of our travel posters, we show a traveler standing on the surface of exoplanet Kepler-16b with two shadows formed by the planet’s two suns. The planet does indeed orbit two stars, but with later size and mass refinements, we now think it would be hard to stand there and enjoy a binary sunset. There isn't a solid surface to stand on a gas planet, and that's what Kepler-16b now appears to be!

In addition to sharing how sublime science can be, these scenes are a reminder that there are lots of careers in the space program, not just scientist, engineer, or astronaut. A creative team at NASA’s Jet Propulsion Laboratory in Southern California produced the travel posters, originally to help share the work of NASA's Exoplanet Exploration Program. They are the result of lots of brainstorming and discussion with real NASA scientists, engineers, and expert communicators. The video versions of these spacey travel scenes were produced by visualization experts at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

All of this work is meant to inspire, and to explore the edge of possibility. It’s also an invitation. With science, we’re stepping into the future. Join us?

Our universe is FULL of strange and surprising things.

And luckily, our Hubble Space Telescope is there to be our window to the unimaginable! Hubble recently ran into an issue with its payload computer which controls and coordinates science instruments onboard the spacecraft. On July 16, teams successfully switched to backup hardware to compensate for the problem! A day later, the telescope resumed normal science operations. To celebrate, we’re taking you back to 2016 when our dear Hubble captured perhaps one of the most intriguing objects in our Milky Way galaxy: a massive star trapped inside a bubble! The star inside this Bubble Nebula burns a million times brighter than our Sun and produces powerful gaseous outflows that howl at more than four million miles per hour. Based on the rate the star is expending energy, scientists estimate in 10 to 20 million years it will explode as a supernova. And the bubble will succumb to a common fate: It’ll pop.

Questions coming up from….

@Dee-an-ugh-deactivated20210528: My 4-year-old is already interested in space. How can I nurture her interest the older she gets in a productive way

@marvelpjostarwarsobssessed: What inspired/caused your interest in space?

@Anonymous: Do you like your job?

Rare & Record-Breaking Black Holes

While even the most “normal” black hole seems exotic compared to the tranquil objects in our solar system, there are some record-breaking oddballs. Tag along as we look at the biggest, closest, farthest, and even “spinniest” black holes discovered in the universe … that we know of right now!

Located 700 million light-years away in the galaxy Holmberg 15A, astronomers found a black hole that is a whopping 40 billion times the mass of the Sun — setting the record for the biggest black hole found so far. On the other hand, the smallest known black hole isn’t quite so easy to pinpoint. There are several black holes with masses around five times that of our Sun. There’s even one candidate with just two and a half times the Sun’s mass, but scientists aren’t sure whether it’s the smallest known black hole or actually the heaviest known neutron star!

You may need to take a seat for this one. The black hole GRS 1915+105 will make you dizzier than an afternoon at an amusement park, as it spins over 1,000 times per second! Maybe even more bizarre than how fast this black hole is spinning is what it means for a black hole to spin at all! What we're actually measuring is how strongly the black hole drags the space-time right outside its event horizon — the point where nothing can escape. Yikes!

If you’re from Earth, the closest black hole that we know of right now, Mon X-1 in the constellation Monoceros, is about 3,000 light-years away. But never fear — that’s still really far away! The farthest known black hole is J0313-1806. The light from its surroundings took a whopping 13 billion years to get to us! And with the universe constantly expanding, that distance continues to grow.

So, we know about large (supermassive, hundreds of thousands to billions of times the Sun's mass) and small (stellar-mass, five to dozens of times the Sun's mass) black holes, but what about other sizes? Though rare, astronomers have found a couple that seem to fit in between and call them intermediate-mass black holes. As for tiny ones, primordial black holes, there is a possibility that they were around when the universe got its start — but there’s not enough evidence so far to prove that they exist!

One thing that’s on astronomers’ wishlist is to see two supermassive black holes crashing into one another. Unfortunately, that event hasn’t been detected — yet! It could be only a matter of time before one reveals itself.

Though these are the records now, in early 2021 … records are meant to be broken, so who knows what we’ll find next!

Add some of these records and rare finds to your black hole-watch list, grab your handy-dandy black hole field guide to learn even more about them — and get to searching!

Keep up with NASA Universe on Facebook and Twitter where we post regularly about black holes.

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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.

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