Scary Space Stories To Tell In The Dark

Astronaut Training: 5 Things You Need to Know

NASA honored the first class of astronaut candidates to graduate under the Artemis program on Friday, Jan. 10, at our Johnson Space Center in Houston.

Out of a record 18,000 applicants, the 11 new astronauts, alongside two from the Canadian Space Agency, have completed two years of training and are now eligible for spaceflight. One day they could embark on missions to the International Space Station, the Moon and even Mars.

Here are five of the training criteria they had to check off to graduate from astronaut candidate to astronaut:

1. Piloting T-38 Jets

Astronauts have been training in T-38 jets since 1957 because the sleek, white jets require crew members to think quickly in dynamic situations and to make decisions that have real consequences. This type of mental experience is critical to preparing for the rigors of spaceflight. It also familiarizes astronaut candidates with checklists and procedures. To check off this training criteria, candidates must be able to safely operate in the T-38 as either a pilot or back seater. 

2. Knowing International Space Station Systems

We are currently flying astronauts to the International Space Station every few months. Astronauts aboard the space station are conducting experiments benefiting humanity on Earth and teaching us how to live longer in space. Astronaut candidates learn to operate and maintain the complex systems aboard the space station as part of their basic training.

3. Conducting Spacewalks

Spacewalks are the hardest thing, physically and mentally, that astronauts do. Astronaut candidates must demonstrate the skills to complete complex spacewalks in our Neutral Buoyancy Laboratory (giant pool used to simulate weightlessness). In order to do so, they will train on the life support systems within the spacesuit, how to handle emergency situations that can arise and how to work effectively as a team to repair the many critical systems aboard the International Space Station to keep it functioning as our science laboratory in space.  

4. Operating Robotics

Astronaut candidates learn the coordinate systems, terminology and how to operate the space station’s two robotic arms called Canadarm2 and Dextre. They train in Canada for a two-week session where they develop more complex robotics skills including capturing visiting cargo vehicles with the arm. The arm, built by the Canadian Space Agency, is capable of handling large cargo and hardware and it helped build the entire space station. It has latches on either end, allowing it to be moved by both flight controllers on the ground and astronauts in space to various parts of the station.

5. Learning Russian Language

The official languages of the International Space Station are English and Russian. All crew members – regardless of what country they come from – are required to know both. NASA astronauts train with their Russian crew mates so it makes sense that they should be able to speak Russian. Astronaut candidates start learning the language at the beginning of their training and train every week, as their schedule allows. 

Now, they are ready for their astronaut pin!

After completing this general training, the new astronauts could be assigned to missions performing research on the International Space Station, launching from American soil on spacecraft built by commercial companies, and launching on deep space missions on our new Orion spacecraft and Space Launch System rocket. 

Watch the Astronaut Candidate Graduation Ceremony

Watch a recording of the astronaut candidate graduation ceremony on our YouTube channel. 

So You Want to Be an Astronaut?

This spring, we’ll once again be accepting applications for the next class of astronauts! Stay tuned to www.nasa.gov/newastronauts for upcoming information on how you can explore places like the Moon and Mars.

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Flying With Fuel From Plants: The Eco-friendly Way to Go

We eat them. We make medicines out of them. Now we’re learning how to use plants as airplane fuel that helps the environment.

Using biofuels to help power jet engines reduces particle emissions in their exhaust by as much as 50 to 70 percent, according to a new study that bodes well for airline economics and Earth’s atmosphere.

All of the aircraft, researchers and flight operations people who made ACCESS II happen. Credits: NASA/Tom Tschida

The findings are the result of a cooperative international research program led by NASA and involving agencies from Germany and Canada, and are detailed in a study published in the journal Nature.

The view from inside NASA's HU-25C Guardian sampling aircraft from very close behind the DC-8. Credits: NASA/SSAI Edward Winstead

Our flight tests collected information about the effects of alternative fuels on engine performance, emissions and aircraft-generated contrails – essentially, human-made clouds - at altitudes flown by commercial airliners. 

The DC-8's four engines burned either JP-8 jet fuel or a 50-50 blend of JP-8 and renewable alternative fuel of hydro processed esters and fatty acids produced from camelina plant oil. Credits: NASA/SSAI Edward Winstead

Contrails are produced by hot aircraft engine exhaust mixing with the cold air that is typical at cruise altitudes several miles above Earth's surface, and are composed primarily of water in the form of ice crystals.

Matt Berry (left), a flight operations engineer at our Armstrong Flight Research Center, reviews the flight plan with Principal Investigator Bruce Anderson. Credits: NASA/Tom Tschida

Researchers are interested in contrails because they create clouds that would not normally form in the atmosphere, and are believed to influence Earth’s environment. 

The alternative fuels tested reduced those emissions. That’s important because contrails have a larger impact on Earth’s atmosphere than all the aviation-related carbon dioxide emissions since the first powered flight by the Wright Brothers.

This photo, taken May 14, 2014, is from the CT-133 aircraft of research partner National Research Council of Canada. It shows the NASA HU-25C Guardian aircraft flying 250 meters behind NASA's DC-8 aircraft before it descends into the DC-8's exhaust plumes to sample ice particles and engine emissions. Credit: National Research Council of Canada

Researchers plan on continuing these studies to understand the benefits of replacing current fuels in aircraft with biofuels. 

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13 Reasons to Have an Out of this World Friday (the 13th)

1. Know that not all of humanity is bound to the ground

Since 2000, the International Space Station has been continuously occupied by humans. There, crew members live and work while conducting important research that benefits life on Earth.

2. Smart people are up all night working in control rooms all over NASA to ensure that data keeps flowing from our satellites

Our satellites help scientists study Earth and space. Satellites looking toward Earth provide information about clouds, oceans, land and ice. They also measure gases in the atmosphere, such as ozone and carbon dioxide, and the amount of energy that Earth absorbs and emits. And satellites monitor wildfires, volcanoes and their smoke.

Satellites that face toward space have a variety of jobs. Some watch for dangerous rays coming from the sun. Others explore asteroids and comets, the history of stars, and the origin of planets. Some satellites fly near or orbit other planets. These spacecraft may look for evidence of water on Mars or capture close-up pictures of Saturn’s rings.

3. When we are ready to send humans to Mars, they’ll have the most high tech space suits ever made

Our Z-2 Spacesuit is the newest prototype in its next-generation platform, the Z-series. Each iteration of the Z-series will advance new technologies that one day will be used in a suit worn by the first humans to step foot on the red planet.

4. When we need more space in space, it could be just like expanding a big high-tech balloon

The Bigelow Expandable Activity Module, or BEAM, leverages key innovations in lightweight and compact materials, departing from a traditional rigid metallic structure. Once attached to the International Space Station, the module would result in an additional 565 cubic feet of volume, which is about the size of a large family camping tent.

5. Even astronauts eat their VEGGIE's

The Vegetable Production System (VEGGIE) is a deployable plant growth unit capable of producing salad-type crops in space. Earlier this year, Expedition 44 crew members, sampled the red romaine lettuce from the VEGGIE plant growth system. This technology will provide future pioneers with a sustainable food supplement during long-duration exploration missions.

6. When you feel far away from home, you can think of the New Horizons spacecraft as it heads toward the Kuiper Belt…billions of miles away

Our New Horizons spacecraft completed its Pluto flyby on July 14, and has continued on its way toward the Kuiper Belt. The spacecraft continues to send back important data as it travels toward deeper space at more than 32,000 miles per hour, and is nearly 3.2 billion miles from Earth.

7. Earth has a magnetic field that largely protects it from the solar wind stripping away our atmosphere…unlike Mars

Recently announced findings from our MAVEN mission have identified the process that appears to have played a key role in the transition of the Martian climate from an early, warm and wet environment to the cold, arid planet Mars is today. MAVEN data have enabled researchers to determine the rate at which the Martian atmosphere currently is losing gas to space via stripping by the solar wind. Luckily, Earth has a magnetic field that largely protects it from this process. 

8. Water bubbles look REALLY cool in space

Astronauts on the International Space Station dissolved an effervescent tablet in a floating ball of water, and captured images using a camera capable of recording four times the resolution of normal high-definition cameras. The higher resolution images and higher frame rate videos can reveal more information when used on science investigations, giving researchers a valuable new tool aboard the space station. This footage is one of the first of its kind.

9. Americans will launch from U.S. soil again with the Commercial Crew Program

Our Commercial Crew Program is working with the American aerospace industry as companies develop and operate a new generation of spacecraft and launch systems capable of carrying crews to low-Earth orbit and the International Space Station.

10. You can see a global image of your home planet…EVERY DAY

Once a day, we will post at least a dozen new color images of Earth acquired from 12 to 36 hours earlier. These images are taken by our EPIC camera from one million miles away on the Deep Space Climate Observatory (DSCOVR). Take a look HERE.

11. Over 18,000 people wanted to be astronauts and join us on the journey to Mars

More than 18,300 people applied to join our 2017 astronaut class, almost three times the number of applications received in 2012 for the most recent astronaut class, and far surpassing the previous record of 8,000 in 1978. Among this group are humanities next great explorers!

12. A lot of NASA-developed tech has been transferred for use to the public

Our Technology Transfer Program highlights technologies that were originally designed for our mission needs, but have since been introduced to the public market. HERE are a few spinoff technologies that you might not know about.

13. If all else fails, there’s this image of Psychedelic Pluto

This false color image of Pluto was created using a technique called principal component analysis. This effect highlights the many subtle color differences between Pluto’s distinct regions.

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Our Space Launch System Rocket’s “Green Run” Engine Testing By the Numbers

We continue to make progress toward the first launch of our Space Launch System (SLS) rocket for the Artemis I mission around the Moon. Engineers at NASA’s Stennis Space Center near Bay St. Louis, Mississippi are preparing for the last two tests of the eight-part SLS core stage Green Run test series.

The test campaign is one of the final milestones before our SLS rocket launches America’s Orion spacecraft to the Moon with the Artemis program. The SLS Green Run test campaign is a series of eight different tests designed to bring the entire rocket stage to life for the first time.

As our engineers and technicians prepare for the wet dress rehearsal and the SLS Green Run hot fire, here are some numbers to keep in mind:

212 Feet

The SLS rocket’s core stage is the largest rocket stage we have ever produced. From top to bottom of its four RS-25 engines, the rocket stage measures 212 feet.

35 Stories

For each of the Green Run tests, the SLS core stage is installed in the historic B-2 Test Stand at Stennis. The test stand was updated to accommodate the SLS rocket stage and is 35 stories tall – or almost 350 feet!

4 RS-25 Engines

All four RS-25 engines will operate simultaneously during the final Green Run Hot Fire. Fueled by the two propellant tanks, the cluster of engines will gimbal, or pivot, and fire for up to eight minutes just as if it were an actual Artemis launch to the Moon.

18 Miles

Our brawny SLS core stage is outfitted with three flight computers and special avionics systems that act as the “brains” of the rocket. It has 18 miles of cabling and more than 500 sensors and systems to help feed fuel and direct the four RS-25 engines.

733,000 Gallons

The stage has two huge propellant tanks that collectively hold 733,000 gallons of super-cooled liquid hydrogen and liquid oxygen. The stage weighs more than 2.3 million pounds when its fully fueled.

114 Tanker Trucks

It’ll take 114 trucks – 54 trucks carrying liquid hydrogen and 60 trucks carrying liquid oxygen – to provide fuel to the SLS core stage.

6 Propellant Barges

A series of barges will deliver the propellant from the trucks to the rocket stage installed in the test stand. Altogether, six propellant barges will send fuel through a special feed system and lines. The propellant initially will be used to chill the feed system and lines to the correct cryogenic temperature. The propellant then will flow from the barges to the B-2 Test Stand and on into the stage’s tanks.

100 Terabytes

All eight of the Green Run tests and check outs will produce more than 100 terabytes of collected data that engineers will use to certify the core stage design and help verify the stage is ready for launch.

For comparison, just one terabyte is the equivalent to 500 hours of movies, 200,000 five-minute songs, or 310,000 pictures!

32,500 holes

The B-2 Test Stand has a flame deflector that will direct the fire produced from the rocket’s engines away from the stage. Nearly 33,000 tiny, handmade holes dot the flame deflector. Why? All those minuscule holes play a huge role by directing constant streams of pressurized water to cool the hot engine exhaust.

One Epic First

When NASA conducts the SLS Green Run Hot Fire test at Stennis, it’ll be the first time that the SLS core stage operates just as it would on the launch pad. This test is just a preview of what’s to come for Artemis I!

The Space Launch System is the only rocket that can send NASA astronauts aboard NASA’s Orion spacecraft and supplies to the Moon in a single mission. The SLS core stage is a key part of the rocket that will send the first woman and the next man to the Moon through NASA’s Artemis program.

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That’s a wrap! Thank you all very much for the wonderful questions.


We’re so excited to send Perseverance off on her journey to Mars, and we will be launching on July 30 at 7:50 a.m. EDT from Kennedy Space Center in Florida. 


If today’s Answer Time got you excited, team up with us to #CoutdownToMars! We created a virtual Mars photo booth, 3D rover experience and more for you to put your own creative touch on sending Perseverance well wishes for her launch to the Red Planet! View them all, HERE. 


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Seeing El Niño…From Space

First, What is El Niño?

This irregularly occurring weather phenomenon is created through an abnormality in wind and ocean circulation. When it originates in the equatorial Pacific Ocean. El Niño has wide-reaching effects. In a global context, it affects rainfall, ocean productivity, atmospheric gases and winds across continents. At a local level, it influences water supplies, fishing industries and food sources.

What About This Year’s El Niño

This winter, weather patterns may be fairly different than what is typical — all because of unusually warm ocean water in the east equatorial Pacific, aka El Niño. California is expected to get more rain while Australia is expected to get less. Since this El Niño began last summer, the Pacific Ocean has already experienced an increase in tropical storms and a decrease in phytoplankton.

How Do We See El Niño?

Here are some of El Niño’s key impacts and how we study them from space:

Rainfall: 

El Niño often spurs a change in rainfall patterns that can lead to major flooding, landslides and droughts across the globe.

How We Study It: Our Global Precipitation Measurement mission (GPM), tracks precipitation worldwide and creates global precipitation maps updated every half-hour using data from a host of satellites. Scientists can then use the data to study changes in rain and snow patterns. This gives us a better understanding of Earth’s climate and weather systems.

Hurricanes:

El Niño also influences the formation of tropical storms. El Niño events are associated with fewer hurricanes in the Atlantic, but more hurricanes and typhoons in the Pacific.

How We Study It: We have a suite of instruments in space that can study various aspects of storms, such as rainfall activity, cloud heights, surface wind speed and ocean heat.

Ocean Ecology:

While El Niño affects land, it also impacts the marine food web, which can be seen in the color of the ocean. The hue of the water is influenced by the presence of tiny plants, sediments and colored dissolved organic material. During El Niño conditions, upwelling is suppressed and the deep, nutrient-rich waters aren’t able to reach the surface, causing less phytoplankton productivity. With less food, the fish population declines, severely affecting fishing industries.

How We Study It: Our satellites measure the color of the ocean to derive surface chlorophyll, a pigment in phytoplankton, and observe lower total chlorophyll amounts during El Niño events in the equatorial Pacific Ocean.

Ozone:

El Niño also influences ozone — a compound that plays an important role in the Earth system and human health. When El Niño occurs, there is a substantial change in the major east-west tropical circulation, causing a significant redistribution of atmospheric gases like ozone.

How We Study It: Our Aura satellite is used to measure ozone concentrations in the upper layer of the atmosphere. With more than a decade of Aura data, researchers are able to separate the response of ozone concentrations to an El Niño from its response to change sin human activity, such as manmade fires.

Fires:

El Niño conditions shift patters of rainfall and fire across the tropics. During El Niño years, the number and intensity of fires increases, especially under drought conditions in regions accustomed to wet weather. These fires not only damage lands, but also emit greenhouse gases that trap heat in the atmosphere and contribute to global warming.

How We Study It: Our MODIS instruments on Aqua and Terra satellites provide a global picture of fire activity. MODIS was specifically designed to observe fires, allowing scientists to discern flaming from smoldering burns.

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In a Warming World, NASA’s Eyes Offer Crucial Views of Hurricanes

June 1 marks the start of hurricane season in the Atlantic Ocean. Last year’s hurricane season saw a record-setting 30 named storms. Twelve made landfall in the United States, also a record. From space, NASA has unique views of hurricanes and works with other government agencies -- like the National Oceanographic and Atmospheric Administration (NOAA) -- to better understand individual storms and entire hurricane seasons.

Here, five ways NASA is changing hurricane science:

1. We can see storms from space

From space, we can see so much more than what’s visible to the naked eye. Among our missions, NASA and NOAA have joint satellite missions monitoring storms in natural color -- basically, what our eyes see -- as well as in other wavelengths of light, which can help identify features our eyes can’t on their own. For instance, images taken in infrared can show the temperatures of clouds, as well as allow us to track the movement of storms at night.

2. We can see inside hurricanes in 3D

If you’ve ever had a CT scan or X-ray done, you know how important 3D imagery can be to understanding what’s happening on the inside. The same concept applies to hurricanes. Our Global Precipitation Measurement mission’s radar and microwave instruments can see through storm clouds to see the precipitation structure of the storm and measure how much total rain is falling as a result of the storm. This information helps scientists understand how the storm may change over time and understand the risk of severe flooding.

We can even virtually fly through hurricanes!

3. We’re looking at how climate change affects hurricane behavior

Climate change is likely causing storms to behave differently. One change is in how storms intensify: More storms are increasing in strength quickly, a process called rapid intensification, where hurricane wind speeds increase by 35 mph (or more) in just 24 hours.

In 2020, a record-tying nine storms rapidly intensified. These quick changes in storm strength can leave communities in their path without time to properly prepare.

Researchers developed a machine learning model that could more accurately detect rapidly intensifying storms.

It’s not just about how quickly hurricanes gain strength. We’re also looking at how climate change may be causing storms to move more slowly, which makes them more destructive. These “stalled” storms can slow to just a few miles an hour, dumping rain and damaging winds on one location at a time. Hurricane Dorian, for example, stalled over Grand Bahama and left catastrophic damage in its wake. Hurricanes Harvey and Florence experienced stalling as well, both causing major flooding.

4. We can monitor damage done by hurricanes

Hurricane Maria reshaped Puerto Rico’s forests. The storm destroyed so many large trees that the overall height of the island’s forests was shortened by one-third. Measurements from the ground, the air, and space gave researchers insights into which trees were more susceptible to wind damage.

Months after Hurricane Maria, parts of Puerto Rico still didn’t have power. Using satellite data, researchers mapped which neighborhoods were still dark and analyzed demographics and physical attributes of the areas with the longest wait for power.

5. We help communities prepare for storms and respond to their aftermath

The data we collect is available for free to the public. We also partner with other federal agencies, like the Federal Emergency Management Agency (FEMA), and regional and local governments to help prepare for and understand the impacts of disasters like hurricanes.

In 2020, our Disasters Program provided data to groups in Alabama, Louisiana, and Central America to identify regions significantly affected by hurricanes. This helps identify vulnerable communities and make informed decisions about where to send resources.

The 2021 Atlantic hurricane season starts today, June 1. Our colleagues at NOAA are predicting another active season, with an above average number of named storms. At NASA, we’re developing new technology to study how storms form and behave, including ways to understand Earth as a system. Working together with our partners at NOAA, FEMA and elsewhere, we’re ready to help communities weather another year of storms.

Bonus: We see storms on other planets, too!

Earth isn’t the only planet with storms. From dust storms on Mars to rains made of glass, we study storms and severe weather on planets in our solar system and beyond. Even the Sun has storms. Jupiter’s Great Red Spot, for instance, is a hurricane-like storm larger than the entire Earth.

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Solar System: Things to Know This Week

See our home planet from Mars, learn about our latest Discovery missions, see stunning imagery from the Cassini mission and more!

1. Our Home

The powerful HiRISE camera on the Mars Reconnaissance Orbiter took this incredible image of our home and moon. The image combines two separate exposures taken on Nov. 20, 2016. 

+ See more 

2. Our Latest Missions of Discovery

We’ve selected two new missions to explore the early solar system. Lucy, a robotic spacecraft scheduled to launch in October 2021, is slated to arrive at its first destination, a main belt asteroid, in 2025. From 2027 to 2033, Lucy will explore six Jupiter Trojan asteroids. These asteroids are trapped by Jupiter's gravity in two swarms that share the planet's orbit, one leading and one trailing Jupiter in its 12-year circuit around the sun.

+Learn more

Psyche, targeted to launch in October 2023, will explore one of the most intriguing targets in the main asteroid belt--a giant metal asteroid, known as 16 Psyche. The asteroid is about 130 miles (210 kilometers) in diameter and thought to be comprised mostly of iron and nickel, similar to Earth's core.

+ Details

3. Image From Cassini  

Cassini took so many jaw-dropping photos last year, how could anyone choose just 10? Well, the Cassini team didn't. Here are 17 amazing photos from Saturn and its moons last year.

4. The Colors of Mars

Impact craters have exposed the subsurface materials on the steep slopes of Mars. However, these slopes often experience rockfalls and debris avalanches that keep the surface clean of dust, revealing a variety of hues, like in this enhanced-color image from our Mars Reconnaissance Orbiter, representing different rock types. 

+ Learn more

5. More From New Horizons

Even though our New Horizons mission flew by Pluto in 2015, the scientific discoveries keep coming. Using a model similar to what meteorologists use to forecast weather and a computer simulation of the physics of evaporating ices, scientists have found evidence of snow and ice features that, until now, had only been seen on Earth.

Discover the full list of 10 things to know about our solar system this week HERE.

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Setting the Standards for Unmanned Aircraft

From advanced wing designs, through the hypersonic frontier, and onward into the era of composite structures, electronic flight controls, and energy efficient flight, our engineers and researchers have led the way in virtually every aeronautic development. And since 2011, aeronautical innovators from around the country have been working on our Unmanned Aircraft Systems integration in the National Airspace System, or UAS in the NAS, project.  

This project was a new type of undertaking that worked to identify, develop, and test the technologies and procedures that will make it possible for unmanned aircraft systems to have routine access to airspace occupied by human piloted aircraft. Since the start, the goal of this unified team was to provide vital research findings through simulations and flight tests to support the development and validation of detect and avoid and command and control technologies necessary for integrating UAS into the NAS.  

That interest moved into full-scale testing and evaluation to determine how to best integrate unmanned vehicles into the national airspace and how to come up with standards moving forward. Normally, 44,000 flights safely take off and land here in the U.S., totaling more than 16 million flights per year. With the inclusion of millions of new types of unmanned aircraft, this integration needs to be seamless in order to keep the flying public safe.

Working hand-in-hand, teams collaborated to better understand how these UAS's would travel in the national airspace by using NASA-developed software in combination with flight tests. Much of this work is centered squarely on technology called detect and avoid.  One of the primary safety concerns with these new systems is the inability of remote operators to see and avoid other aircraft.  Because unmanned aircraft literally do not have a pilot on board, we have developed concepts allowing safe operation within the national airspace.  

In order to better understand how all the systems work together, our team flew a series of tests to gather data to inform the development of minimum operational performance standards for detect and avoid alerting guidance. Over the course of this testing, we gathered an enormous amount of data allowing safe integration for unmanned aircraft into the national airspace. As unmanned aircraft are becoming more ubiquitous in our world - safety, reliability, and proven research must coexist.

Every day new use case scenarios and research opportunities arise based around the hard work accomplished by this incredible workforce. Only time will tell how these new technologies and innovations will shape our world.

Want to learn the many ways that NASA is with you when you fly? Visit nasa.gov/aeronautics.



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The Lives, Times, and Deaths of Stars

Who among us doesn’t covertly read tabloid headlines when we pass them by? But if you’re really looking for a dramatic story, you might want to redirect your attention from Hollywood’s stars to the real thing. From birth to death, these burning spheres of gas experience some of the most extreme conditions our cosmos has to offer.

All stars are born in clouds of dust and gas like the Pillars of Creation in the Eagle Nebula pictured below. In these stellar nurseries, clumps of gas form, pulling in more and more mass as time passes. As they grow, these clumps start to spin and heat up. Once they get heavy and hot enough (like, 27 million degrees Fahrenheit or 15 million degrees Celsius), nuclear fusion starts in their cores. This process occurs when protons, the nuclei of hydrogen atoms, squish together to form helium nuclei. This releases a lot of energy, which heats the star and pushes against the force of its gravity. A star is born.

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

From then on, stars’ life cycles depend on how much mass they have. Scientists typically divide them into two broad categories: low-mass and high-mass stars. (Technically, there’s an intermediate-mass category, but we’ll stick with these two to keep it straightforward!)

Low-mass stars

A low-mass star has a mass eight times the Sun's or less and can burn steadily for billions of years. As it reaches the end of its life, its core runs out of hydrogen to convert into helium. Because the energy produced by fusion is the only force fighting gravity’s tendency to pull matter together, the core starts to collapse. But squeezing the core also increases its temperature and pressure, so much so that its helium starts to fuse into carbon, which also releases energy. The core rebounds a little, but the star’s atmosphere expands a lot, eventually turning into a red giant star and destroying any nearby planets. (Don’t worry, though, this is several billion years away for our Sun!)

Red giants become unstable and begin pulsating, periodically inflating and ejecting some of their atmospheres. Eventually, all of the star’s outer layers blow away, creating an expanding cloud of dust and gas misleadingly called a planetary nebula. (There are no planets involved.)

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

All that’s left of the star is its core, now called a white dwarf, a roughly Earth-sized stellar cinder that gradually cools over billions of years. If you could scoop up a teaspoon of its material, it would weigh more than a pickup truck. (Scientists recently found a potential planet closely orbiting a white dwarf. It somehow managed to survive the star’s chaotic, destructive history!)

High-mass stars

A high-mass star has a mass eight times the Sun’s or more and may only live for millions of years. (Rigel, a blue supergiant in the constellation Orion, pictured below, is 18 times the Sun’s mass.)

Credit: Rogelio Bernal Andreo

A high-mass star starts out doing the same things as a low-mass star, but it doesn’t stop at fusing helium into carbon. When the core runs out of helium, it shrinks, heats up, and starts converting its carbon into neon, which releases energy. Later, the core fuses the neon it produced into oxygen. Then, as the neon runs out, the core converts oxygen into silicon. Finally, this silicon fuses into iron. These processes produce energy that keeps the core from collapsing, but each new fuel buys it less and less time. By the point silicon fuses into iron, the star runs out of fuel in a matter of days. The next step would be fusing iron into some heavier element, but doing requires energy instead of releasing it.  

The star’s iron core collapses until forces between the nuclei push the brakes, and then it rebounds back to its original size. This change creates a shock wave that travels through the star’s outer layers. The result is a huge explosion called a supernova.

What’s left behind depends on the star’s initial mass. Remember, a high-mass star is anything with a mass more than eight times the Sun’s — which is a huge range! A star on the lower end of this spectrum leaves behind a city-size, superdense neutron star. (Some of these weird objects can spin faster than blender blades and have powerful magnetic fields. A teaspoon of their material would weigh as much as a mountain.)

At even higher masses, the star’s core turns into a black hole, one of the most bizarre cosmic objects out there. Black holes have such strong gravity that light can’t escape them. If you tried to get a teaspoon of material to weigh, you wouldn’t get it back once it crossed the event horizon — unless it could travel faster than the speed of light, and we don’t know of anything that can! (We’re a long way from visiting a black hole, but if you ever find yourself near one, there are some important safety considerations you should keep in mind.)

The explosion also leaves behind a cloud of debris called a supernova remnant. These and planetary nebulae from low-mass stars are the sources of many of the elements we find on Earth. Their dust and gas will one day become a part of other stars, starting the whole process over again.

That’s a very brief summary of the lives, times, and deaths of stars. (Remember, there’s that whole intermediate-mass category we glossed over!) To keep up with the most recent stellar news, follow NASA Universe on Twitter and Facebook.

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