What’s Enceladus?

Solar System: Things to Know This Week

Learn about supermoons, read the monthly blog from the Dawn mission’s chief engineer and more.

1. This Is the Season for Supermoons 

The second of three fall supermoons occurred on November 14 and the final one is December. What are supermoons? Since the moon’s orbit is elliptical, one side (perigee) is about 30,000 miles closer to Earth than the other (apogee). The word syzygy, in addition to being useful in word games, is the scientific name for when the Earth, sun, and moon line up as the moon orbits Earth. When perigee-syzygy of the Earth-moon-sun system occurs and the moon is on the opposite side of the Earth from the sun, we get a perigee moon or more commonly, a supermoon!

+ Learn more 

2. Dawn Mission Blog

When Dawn arrived at Ceres in March 2015, it became the first spacecraft to reach a dwarf planet  Meet the Dawn mission’s chief engineer Dr. Marc Rayman and read his insightful blogs about the mission. 

+ Latest Blog

+  All Mission Managers Blogs

3. The Seas of Titan

On its penultimate close flyby of Saturn’s largest moon Titan, Cassini will use its radio science instrument to scan the great seas of methane near the moon’s North Pole. Titan’s three large northern seas, Punga Mare, Ligeia Mare and Kraken Mare, are each hundreds of miles across, but imaging cameras can’t see them very well because the moon’s surface is veiled by a thick haze. Radio signals, however, can penetrate the moon’s atmosphere, and Cassini has an instrument that uses radio signals to reveal Titan's dramatic landscapes.

+ See a map of Titan’s methane seas

4.  Spot the Station!

Have you ever seen the International Space Station fly over your town? Do you want to? 

+ Here's how and where and when to look

5. The Science of Light, Celebrating Dark Skies in Our National Parks

Learning more about the science of light and human vision will help us understand the value and fragility of natural lightscapes. During the day, the surface of the planet is bathed in light from the sun. The energy in sunlight drives weather, the water cycle, and ecosystems. But at night, in the absence of bright light, our atmosphere turns transparent and allows us to see beyond our planet into the vastness of the cosmos.

+ More

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

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

Don’t Say “Bye, Bye, Bye” To Your Vision: Solar Eclipse Safety Tips

On Oct. 14, 2023, many people across North, Central, and South America will have an opportunity to view a “ring of fire” eclipse – an annular solar eclipse – when the Moon passes between the Earth and Sun! During an annular eclipse, it is never safe to look directly at the Sun without specialized eye protection designed for solar viewing. To spread the word, *NSYNC's Lance Bass stopped by to share some tips on how to stay safe while viewing a solar eclipse.

Check out these detailed viewing maps to see if you will be able to see the entire or partial solar eclipse. If you are, make sure your solar viewing glasses have the ISO certification 12312-2. You can also check with local libraries or science museums to see if they have safe solar viewing glasses to hand out. You can also make a simple pinhole camera at home with some paper and aluminum foil: go.nasa.gov/pinholeprojector

Everyone online can watch the eclipse with NASA. Set a reminder to watch live: https://www.youtube.com/watch?v=LlY79zjud-Q

Make sure to follow us on Tumblr for your regular dose of space!

9 Ocean Facts You Likely Don’t Know, but Should

Earth is a place dominated by water, mainly oceans. It’s also a place our researchers study to understand life. Trillions of gallons of water flow freely across the surface of our blue-green planet. Ocean’s vibrant ecosystems impact our lives in many ways. 

In celebration of World Oceans Day, here are a few things you might not know about these complex waterways.

1. Why is the ocean blue? 

The way light is absorbed and scattered throughout the ocean determines which colors it takes on. Red, orange, yellow,and green light are absorbed quickly beneath the surface, leaving blue light to be scattered and reflected back. This causes us to see various blue and violet hues.

2. Want a good fishing spot? 

Follow the phytoplankton! These small plant-like organisms are the beginning of the food web for most of the ocean. As phytoplankton grow and multiply, they are eaten by zooplankton, small fish and other animals. Larger animals then eat the smaller ones. The fishing industry identifies good spots by using ocean color images to locate areas rich in phytoplankton. Phytoplankton, as revealed by ocean color, frequently show scientists where ocean currents provide nutrients for plant growth.

3. The ocean is many colors. 

When we look at the ocean from space, we see many different shades of blue. Using instruments that are more sensitive than the human eye, we can measure carefully the fantastic array of colors of the ocean. Different colors may reveal the presence and amount of phytoplankton, sediments and dissolved organic matter.

4. The ocean can be a dark place. 

About 70 percent of the planet is ocean, with an average depth of more than 12,400 feet. Given that light doesn’t penetrate much deeper than 330 feet below the water’s surface (in the clearest water), most of our planet is in a perpetual state of darkness. Although dark, this part of the ocean still supports many forms of life, some of which are fed by sinking phytoplankton. 

5. We study all aspects of ocean life. 

Instruments on satellites in space, hundreds of kilometers above us, can measure many things about the sea: surface winds, sea surface temperature, water color, wave height, and height of the ocean surface.

6. In a gallon of average sea water, there is about 1/2 cup of salt. 

The amount of salt varies depending on location. The Atlantic Ocean is saltier than the Pacific Ocean, for instance. Most of the salt in the ocean is the same kind of salt we put on our food: sodium chloride.

7. A single drop of sea water is teeming with life.  

It will most likely have millions (yes, millions!) of bacteria and viruses, thousands of phytoplankton cells, and even some fish eggs, baby crabs, and small worms. 

8. Where does Earth store freshwater? 

Just 3.5 percent of Earth’s water is fresh—that is, with few salts in it. You can find Earth’s freshwater in our lakes, rivers, and streams, but don’t forget groundwater and glaciers. Over 68 percent of Earth’s freshwater is locked up in ice and glaciers. And another 30 percent is in groundwater. 

9. Phytoplankton are the “lungs of the ocean”.

Just like forests are considered the “lungs of the earth”, phytoplankton is known for providing the same service in the ocean! They consume carbon dioxide, dissolved in the sunlit portion of the ocean, and produce about half of the world’s oxygen. 

Want to learn more about how we study the ocean? Follow @NASAEarth on twitter.

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

How Well Do You Know Mercury?

Mercury is the smallest planet in our solar system and is only slightly larger than Earth’s moon. To give you some perspective, if the sun were as tall as a typical front door, Earth would be the size of a nickel and Mercury would be about as big as a green pea.

Mercury is the closest planet to the sun. Daytime temperatures can reach 430 degrees Celsius (800 degrees Fahrenheit) and drop to –180 degrees Celsius (-290 degrees Fahrenheit) at night.

Here are a few fun facts about Mercury:

Mercury takes only 88 Earth days to orbit the sun

If we could stand on Mercury’s surface when it is at its closest point to the sun, the sun would appear more than three times larger than it does here on Earth

Mercury is home to one of the largest impact basins in the solar system: the Caloris Basin. The diameter of this impact basin is the length of 16,404 football fields (minus the end zones) placed end to end!

Mercury is one of only two planets in our solar system that do not have moons (Venus is the other one)

Mercury completes three rotations for every two orbits around the sun. That means that if you wanted to stay up from sunrise to sunrise on Mercury, you’d be up for 176 Earth days…you’d need a LOT of coffee! 

Two missions have visited Mercury:

Mariner 10 was the first mission to Mercury, and 30 years later, our MESSENGER mission was the second to visit the planet. Mariner 10 was also the first spacecraft to reach one planet by using the gravity of another planet (in this case, Venus) to alter its speed and trajectory.

MESSENGER was the first spacecraft to orbit Mercury, The spacecraft had its own shades to protect it from the light of the sun. This is important since sunlight on Mercury can be as much as 11 times brighter than it is here on Earth. The spacecraft was originally planned to orbit Mercury for one year, but exceeded expectations and worked for over four years capturing extensive data. On April 30, 2015, the spacecraft succumbed to the pull of solar gravity and impacted Mercury’s surface.

Water Ice?

The MESSENGER spacecraft observed compelling support for the long-held hypothesis that Mercury harbors abundant water ice and other frozen volatile materials in its permanently shadowed polar craters.

This radar image of Mercury’s north polar region. The areas shown in red were captured by MESSENGER, compared to the yellow deposits imaged by Earth-based radar. These areas are believed to consist of water ice.

Mercury Transit of the Sun

For more than seven hours on Monday, May 9, Mercury will be visible as a tiny black dot crossing the face of the sun. This rare event – which happens only slightly more than once a decade – is called a transit.

Where: Skywatchers in Western Europe, South America and eastern North America will be able to see the entirety of the transit. The entire 7.5-hour path across the sun will be visible across the Eastern U.S. – with magnification and proper solar filters – while those in the West can observe the transit in progress at sunrise.

Watch: We will stream a live program on NASA TV and the agency’s Facebook page from 10:30 to 11:30 a.m. – an informal roundtable during which experts representing planetary, heliophysics and astrophysics will discuss the science behind the Mercury transit. Viewers can ask questions via Facebook and Twitter using #AskNASA. Unlike the 2012 Venus transit of the sun, Mercury is too small to be visible without magnification from a telescope or high-powered binoculars. Both must have safe solar filters made of specially-coated glass or Mylar; you can never look directly at the sun.

To learn more about our solar system and the planets, visit: http://solarsystem.nasa.gov/

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

Celestial Geometry: Equinoxes and Eclipses

March 20 marks the spring equinox. It’s the first day of astronomical spring in the Northern Hemisphere, and one of two days a year when day and night are just about equal lengths across the globe.

Because Earth is tilted on its axis, there are only two days a year when the sun shines down exactly over the equator, and the day/night line – called the terminator – runs straight from north to south.

In the Northern Hemisphere, the March equinox marks the beginning of spring – meaning that our half of Earth is slowly tilting towards the sun, giving us longer days and more sunlight, and moving us out of winter and into spring and summer.

An equinox is the product of celestial geometry, and there’s another big celestial event coming up later this year: a total solar eclipse.

A solar eclipse happens when the moon blocks our view of the sun. This can only happen at a new moon, the period about once each month when the moon’s orbit positions it between the sun and Earth — but solar eclipses don’t happen every month.  

The moon’s orbit around Earth is inclined, so, from Earth's view, on most months we see the moon passing above or below the sun. A solar eclipse happens only on those new moons where the alignment of all three bodies are in a perfectly straight line.

On Aug. 21, 2017, a total solar eclipse will be visible in the US along a narrow, 70-mile-wide path that runs from Oregon to South Carolina. Throughout the rest of North America – and even in parts of South America, Africa, Europe and Asia – the moon will partially obscure the sun.

Within the path of totality, the moon will completely cover the sun’s overwhelmingly bright face, revealing the relatively faint outer atmosphere, called the corona, for seconds or minutes, depending on location.

It’s essential to observe eye safety during an eclipse. Though it’s safe to look at the eclipse ONLY during the brief seconds of totality, you must use a proper solar filter or indirect viewing method when any part of the sun’s surface is exposed – whether during the partial phases of an eclipse, or just on a regular day.

Learn more about the August eclipse at eclipse2017.nasa.gov.

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

How Do You Stay Fit on a Mission to Mars?

This mini exercise device could be the key!

Onboard the International Space Station, astronauts need to work out to maintain their bone density and muscle mass, usually exercising 2 hours every single day. Throughout the week, they exercise on three different pieces of equipment--a bike, a treadmill and the Advanced Restive Exercise Device (ARED).

All these devices are needed to keep an astronaut healthy.

However, deep-space vehicles like our Orion Spacecraft aren’t as roomy as station, so everything — including exercise equipment — needs to be downsized. The Miniature Exercise Device (MED-2) is getting us one step closer to being able to keep astronauts’ bodies healthy on long journeys to the moon, Mars and beyond.

MED-2 is a compact, all-in-one exercise device that we developed and will be launching to the space station Tuesday, March 22. Onboard the station, we’ll see how MED-2 will perform in microgravity and how it will need to be further adapted for our Journey to Mars. However, it’s already pretty well equipped for deep space missions.

So what makes MED-2 so great for deep space travel and our Journey to Mars?

1. It is an all-in-one exercise device, meaning it can do both aerobic and resistive workouts. When we go to Mars, the less equipment we need, the better.

2. It's incredibly light. The MED-2 weighs only 65 pounds, and every pound counts during space missions.

3. It has 5 - 350 pounds of resistance, despite weighing only 65 pounds. Astronauts don’t all lift the same amount, making the flexibility in MED-2’s “weights” essential.

4. It's tiny. (Hence its name Miniature Exercise Device.) Not only is MED-2 incredibly light, but it also won't take up a lot of space on any craft.

5. It powers itself. During an aerobic workout, the device charges, and then that power is used to run the resistive exercises. When traveling to space, it's good when nothing goes to waste, and now astronauts' workouts will help power the Journey to Mars.

MED-2 is only one of many devices and experiments flying on Orbital ATK’s Cygnus spacecraft. To find out more about the science on the space station, follow @ISS_Research and @Space_Station on Twitter.

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

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.

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

Travel Posters of Fantastic Excursions

What would the future look like if people were regularly visiting to other planets and moons? These travel posters give a glimpse into that imaginative future. Take a look and choose your destination:

The Grand Tour

Our Voyager mission took advantage of a once-every-175-year alignment of the outer planets for a grand tour of the solar system. The twin spacecraft revealed details about Jupiter, Saturn, Uranus and Neptune – using each planet’s gravity to send them on to the next destination.

Mars

Our Mars Exploration Program seeks to understand whether Mars was, is, or can be a habitable world. This poster imagines a future day when we have achieved our vision of human exploration of the Red Planet and takes a nostalgic look back at the great imagined milestones of Mars exploration that will someday be celebrated as “historic sites.”

Earth

There’s no place like home. Warm, wet and with an atmosphere that’s just right, Earth is the only place we know of with life – and lots of it. Our Earth science missions monitor our home planet and how it’s changing so it can continue to provide a safe haven as we reach deeper into the cosmos.

Venus

The rare science opportunity of planetary transits has long inspired bold voyages to exotic vantage points – journeys such as James Cook’s trek to the South Pacific to watch Venus and Mercury cross the face of the sun in 1769. Spacecraft now allow us the luxury to study these cosmic crossings at times of our choosing from unique locales across our solar system.

Ceres

Ceres is the closest dwarf planet to the sun. It is the largest object in the main asteroid belt between Mars and Jupiter, with an equatorial diameter of about 965 kilometers. After being studied with telescopes for more than two centuries, Ceres became the first dwarf planet to be explored by a spacecraft, when our Dawn probe arrived in orbit in March 2015. Dawn’s ongoing detailed observations are revealing intriguing insights into the nature of this mysterious world of ice and rock.

Jupiter

The Jovian cloudscape boasts the most spectacular light show in the solar system, with northern and southern lights to dazzle even the most jaded space traveler. Jupiter’s auroras are hundreds of times more powerful than Earth’s, and they form a glowing ring around each pole that’s bigger than our home planet. 

Enceladus

The discovery of Enceladus’ icy jets and their role in creating Saturn’s E-ring is one of the top findings of the Cassini mission to Saturn. Further Cassini discoveries revealed strong evidence of a global ocean and the first signs of potential hydrothermal activity beyond Earth – making this tiny Saturnian moon one of the leading locations in the search for possible life beyond Earth.

Titan

Frigid and alien, yet similar to our own planet billions of years ago, Saturn’s largest moon, Titan has a thick atmosphere, organic-rich chemistry and surface shaped by rivers and lakes of liquid ethane and methane. Our Cassini orbiter was designed to peer through Titan’s perpetual haze and unravel the mysteries of this planet-like moon.

Europa

Astonishing geology and the potential to host the conditions for simple life making Jupiter’s moon Europa a fascinating destination for future exploration. Beneath its icy surface, Europa is believed to conceal a global ocean of salty liquid water twice the volume of Earth’s oceans. Tugging and flexing from Jupiter’s gravity generates enough heat to keep the ocean from freezing.

You can download free poster size images of these thumbnails here: http://www.jpl.nasa.gov/visions-of-the-future/

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

When you're finally up out of the air, high enough to see the Earth, what is it like to see our home planet from above for the first time?

Blowing Bubbles in the Gamma-ray Sky

Did you know our Milky Way galaxy is blowing bubbles? Two of them, each 25,000 light-years tall! They extend above and below the disk of the galaxy, like the two halves of an hourglass. We can’t see them with our own eyes because they’re only apparent in gamma-ray light, the highest-energy light in the universe.

We didn’t even know these humongous structures were smack in the middle of our galaxy until 2010. Scientists found them when they analyzed the first two years of data from NASA’s Fermi Gamma-ray Space Telescope. They dubbed them the “Fermi bubbles” and found that in addition to being really big and spread out, they seem to have well-defined edges. The bubbles’ shape and the light they give off led scientists to think they were created by a rapid release of energy. But by what? And when?

One possible explanation is that they could be leftovers from the last big meal eaten by the supermassive black hole at the center of our galaxy. This monster is more than 4 million times the mass of our own Sun. Scientists think it may have slurped up a big cloud of hydrogen between 6 and 9 million years ago and then burped jets of hot gas that we see in gamma rays and X-rays.

Another possible explanation is that the bubbles could be the remains of star formation. There are massive clusters of stars at very the center of the Milky Way — sometimes the stars are so closely packed they’re a million times more dense than in the outer suburb of the galaxy where we live. If there was a burst of star formation in this area a few million years ago, it could have created the surge of gas needed to in turn create the Fermi bubbles.

It took us until 2010 to see these Fermi bubbles because the sky is filled with a fog of other gamma rays that can obscure our view. This fog is created when particles moving near light speed bump into gas, dust, and light in the Milky Way. These collisions produce gamma rays, and scientists had to factor out the fog to unveil the bubbles.

Scientists continue to study the possible causes of these massive bubbles using the 10 years of data Fermi has collected so far. Fermi has also made many other exciting discoveries — like the the collision of superdense neutron stars and the nature of space-time. Learn more about Fermi and how we’ve been celebrating its first decade in space.

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