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Three moons of Jupiter : Ganymede, Callisto and Io. Credits : NASA/JPL.

Happy Earth Day

The First Photograph of the Dark Side of the Moon from 1959

With the launch of Sputnik in 1957, the Soviet Union kicked off the Space Race and for the first several years (arguable up until the Moon landing in ‘69), they dominated the United States. One of their “firsts” in the early years was taking the first photo of the dark side of the Moon 60 years ago this month.

Astronomer Kevin Hainline wrote a fascinating account of how the Soviet’s Luna 3 spacecraft took the photo and then transmitted it back to Earth.

First off, Luna 3, the first three-axis stabilized spacecraft, had to reach the Moon to take the pictures, and it had to use a little photocell to orient towards the Moon so that now, while stabilized, it could take the pictures. Which it did. On PHOTOGRAPHIC FILM.

And it gets WILDER because these photos were then moved to a little CHEMICAL PLANT to DEVELOP AND DRY THEM. That’s right, Luna 3 had a little 1 Hour Photo inside. Now you’re thinking, well, how do you get those actual photos back to the Earth?

How indeed? The spacecraft faxed the photos to Earth. A few years later, when the Soviets’ Luna 9 took the first photo on the Moon’s surface and went to transmit it back to Earth, a group in the UK was able to read the signal with a fax machine and the resulting image was published the next day on the front page of the Daily Express.

Earth and Moon

Earth and Moon

Earth from Afar

“It suddenly struck me that that tiny pea, pretty and blue, was the Earth. I put up my thumb and shut one eye, and my thumb blotted out the planet Earth. I didn’t feel like a giant. I felt very, very small.” - Neil Armstrong, Apollo 11

This week we’re celebrating Earth Day 2018 with some of our favorite images of Earth from afar…

At 7.2 million Miles…and 4 Billion Miles

Voyager famously captured two unique views of our homeworld from afar. One image, taken in 1977 from a distance of 7.3 million miles (11.7 million kilometers) (above), showed the full Earth and full Moon in a single frame for the first time in history. The second (below), taken in 1990 as part of a “family portrait of our solar system from 4 billion miles (6.4 billion kilometers), shows Earth as a tiny blue speck in a ray of sunlight.” This is the famous “Pale Blue Dot” image immortalized by Carl Sagan.

“This was our willingness to see the Earth as a one-pixel object in a far greater cosmos,” Sagan’s widow, Ann Druyan said of the image. “It’s that humility that science gives us. That weans us from our childhood need to be the center of things. And Voyager gave us that image of the Earth that is so heart tugging because you can’t look at that image and not think of how fragile, how fragile our world is. How much we have in common with everyone with whom we share it; our relationship, our relatedness, to everyone on this tiny pixel.“

A Bright Flashlight in a Dark Sea of Stars

Our Kepler mission captured Earth’s image as it slipped past at a distance of 94 million miles (151 million kilometers). The reflection was so extraordinarily bright that it created a saber-like saturation bleed across the instrument’s sensors, obscuring the neighboring Moon.

Hello and Goodbye

This beautiful shot of Earth as a dot beneath Saturn’s rings was taken in 2013 as thousands of humans on Earth waved at the exact moment the spacecraft pointed its cameras at our home world. Then, in 2017, Cassini caught this final view of Earth between Saturn’s rings as the spacecraft spiraled in for its Grand Finale at Saturn.

‘Simply Stunning’

”The image is simply stunning. The image of the Earth evokes the famous ‘Blue Marble’ image taken by astronaut Harrison Schmitt during Apollo 17…which also showed Africa prominently in the picture.“ -Noah Petro, Deputy Project Scientist for our Lunar Reconnaissance Orbiter mission.

Goodbye—for now—at 19,000 mph

As part of an engineering test, our OSIRIS-REx spacecraft captured this image of Earth and the Moon in January 2018 from a distance of 39.5 million miles (63.6 million kilometers). When the camera acquired the image, the spacecraft was moving away from our home planet at a speed of 19,000 miles per hour (8.5 kilometers per second). Earth is the largest, brightest spot in the center of the image, with the smaller, dimmer Moon appearing to the right. Several constellations are also visible in the surrounding space.

The View from Mars

A human observer with normal vision, standing on Mars, could easily see Earth and the Moon as two distinct, bright "evening stars.”

Moon Photobomb

“This image from the Deep Space Climate Observatory (DSCOVR) satellite captured a unique view of the Moon as it moved in front of the sunlit side of Earth in 2015. It provides a view of the far side of the Moon, which is never directly visible to us here on Earth. “I found this perspective profoundly moving and only through our satellite views could this have been shared.” - Michael Freilich, Director of our Earth Science Division.

Eight Days Out

Eight days after its final encounter with Earth—the second of two gravitational assists from Earth that helped boost the spacecraft to Jupiter—the Galileo spacecraft looked back and captured this remarkable view of our planet and its Moon. The image was taken from a distance of about 3.9 million miles (6.2 million kilometers).

A Slice of Life

Earth from about 393,000 miles (633,000 kilometers) away, as seen by the European Space Agency’s comet-bound Rosetta spacecraft during its third and final swingby of our home planet in 2009.

So Long Earth

The Mercury-bound MESSENGER spacecraft captured several stunning images of Earth during a gravity assist swingby of our home planet on Aug. 2, 2005.

Earth Science: Taking a Closer Look

Our home planet is a beautiful, dynamic place. Our view from Earth orbit sees a planet at change. Check out more images of our beautiful Earth here.

Join Our Earth Day Celebration!

We pioneer and supports an amazing range of advanced technologies and tools to help scientists and environmental specialists better understand and protect our home planet - from space lasers to virtual reality, small satellites and smartphone apps. 

To celebrate Earth Day 2018, April 22, we are highlighting many of these innovative technologies and the amazing applications behind them.

Learn more about our Earth Day plans HERE. 

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The Space Shuttle Discovery blasts off from Cape Canaveral on March 13, 1989.

The Moon in Motion

Happy New Year! And happy supermoon! Tonight, the Moon will appear extra big and bright to welcome us into 2018 – about 6% bigger and 14% brighter than the average full Moon. And how do we know that? Well, each fall, our science visualizer Ernie Wright uses data from the Lunar Reconnaissance Orbiter (LRO) to render over a quarter of a million images of the Moon. He combines these images into an interactive visualization, Moon Phase and Libration, which depicts the Moon at every day and hour for the coming year. 

Want to see what the Moon will look like on your birthday this year? Just put in the date, and even the hour (in Universal Time) you were born to see your birthday Moon.

Our Moon is quite dynamic. In addition to Moon phases, our Moon appears to get bigger and smaller throughout the year, and it wobbles! Or at least it looks that way to us on Earth. This wobbling is called libration, from the Latin for ‘balance scale’ (libra). Wright relies on LRO maps of the Moon and NASA orbit calculations to create the most accurate depiction of the 6 ways our Moon moves from our perspective.

1. Phases

The Moon phases we see on Earth are caused by the changing positions of the Earth and Moon relative to the Sun. The Sun always illuminates half of the Moon, but we see changing shapes as the Moon revolves around the Earth. Wright uses a software library called SPICE to calculate the position and orientation of the Moon and Earth at every moment of the year. With his visualization, you can input any day and time of the year and see what the Moon will look like!

2. Shape of the Moon

Check out that crater detail! The Moon is not a smooth sphere. It’s covered in mountains and valleys and thanks to LRO, we know the shape of the Moon better than any other celestial body in the universe. To get the most accurate depiction possible of where the sunlight falls on the lunar surface throughout the month, Wright uses the same graphics software used by Hollywood design studios, including Pixar, and a method called ‘raytracing’ to calculate the intricate patterns of light and shadow on the Moon’s surface, and he checks the accuracy of his renders against photographs of the Moon he takes through his own telescope.

3. Apparent Size 

The Moon Phase and Libration visualization shows you the apparent size of the Moon. The Moon’s orbit is elliptical, instead of circular - so sometimes it is closer to the Earth and sometimes it is farther. You’ve probably heard the term “supermoon.” This describes a full Moon at or near perigee (the point when the Moon is closest to the Earth in its orbit). A supermoon can appear up to 14% bigger and brighter than a full Moon at apogee (the point when the Moon is farthest from the Earth in its orbit). 

Our supermoon tonight is a full Moon very close to perigee, and will appear to be about 14% bigger than the July 27 full Moon, the smallest full Moon of 2018, occurring at apogee. Input those dates into the Moon Phase and Libration visualization to see this difference in apparent size!

4. East-West Libration

Over a month, the Moon appears to nod, twist, and roll. The east-west motion, called ‘libration in longitude’, is another effect of the Moon’s elliptical orbital path. As the Moon travels around the Earth, it goes faster or slower, depending on how close it is to the Earth. When the Moon gets close to the Earth, it speeds up thanks to an additional pull from Earth’s gravity. Then it slows down, when it’s farther from the Earth. While this speed in orbital motion changes, the rotational speed of the Moon stays constant. 

This means that when the Moon moves faster around the Earth, the Moon itself doesn’t rotate quite enough to keep the same exact side facing us and we get to see a little more of the eastern side of the Moon. When the Moon moves more slowly around the Earth, its rotation gets a little ahead, and we see a bit more of its western side.

5. North-South Libration

The Moon also appears to nod, as if it were saying “yes,” a motion called ‘libration in latitude’. This is caused by the 5 degree tilt of the Moon’s orbit around the Earth. Sometimes the Moon is above the Earth’s northern hemisphere and sometimes it’s below the Earth’s southern hemisphere, and this lets us occasionally see slightly more of the northern or southern hemispheres of the Moon! 

6. Axis Angle

Finally, the Moon appears to tilt back and forth like a metronome. The tilt of the Moon’s orbit contributes to this, but it’s mostly because of the 23.5 degree tilt of our own observing platform, the Earth. Imagine standing sideways on a ramp. Look left, and the ramp slopes up. Look right and the ramp slopes down. 

Now look in front of you. The horizon will look higher on the right, lower on the left (try this by tilting your head left). But if you turn around, the horizon appears to tilt the opposite way (tilt your head to the right). The tilted platform of the Earth works the same way as we watch the Moon. Every two weeks we have to look in the opposite direction to see the Moon, and the ground beneath our feet is then tilted the opposite way as well.

So put this all together, and you get this:

Beautiful isn’t it? See if you can notice these phenomena when you observe the Moon. And keep coming back all year to check on the Moon’s changing appearance and help plan your observing sessions.

Follow @NASAMoon on Twitter to keep up with the latest lunar updates. 

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

Gorgeous ultra HD fly-through of the inside of the International Space Station

NASA has uploaded a beautiful and relaxing 18-minute fly-through video of the International Space Station filmed in ultra high-definition 4K resolution. They used to a fisheye lens to film it, which means you get plenty of detail and depth of field.

Phobos

Exercising in space – Quick video about my favorite fitness machine

#Fitness is critical in space! Watch this #SpeedyTime video as I transform the multi-modal ARED machine during my workout. The Advanced Resistive Exercise Device (ARED), simulates free-weight exercises in normal gravity. In space we exercise 2 hours every day in order to maintain our muscle and bone mass. Our favorite part about exercising in space is of course, the view!

To learn more about the ARED, please visit https://www.nasa.gov/mission_pages/station/research/experiments/1001.html

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.

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Magnetospheres: How Do They Work?

The sun, Earth, and many other planets are surrounded by giant magnetic bubbles.

Space may seem empty, but it’s actually a dynamic place, dominated by invisible forces, including those created by magnetic fields.  Magnetospheres – the areas around planets and stars dominated by their magnetic fields – are found throughout our solar system. They deflect high-energy, charged particles called cosmic rays that are mostly spewed out by the sun, but can also come from interstellar space. Along with atmospheres, they help protect the planets’ surfaces from this harmful radiation.

It’s possible that Earth’s protective magnetosphere was essential for the development of conditions friendly to life, so finding magnetospheres around other planets is a big step toward determining if they could support life.

But not all magnetospheres are created equal – even in our own backyard, not all planets in our solar system have a magnetic field, and the ones we have observed are all surprisingly different.

Earth’s magnetosphere is created by the constantly moving molten metal inside Earth. This invisible “force field” around our planet has an ice cream cone-like shape, with a rounded front and a long, trailing tail that faces away from the sun. The magnetosphere is shaped that way because of the constant pressure from the solar wind and magnetic fields on the sun-facing side.

Earth’s magnetosphere deflects most charged particles away from our planet – but some do become trapped in the magnetic field and create auroras when they rain down into the atmosphere.

We have several missions that study Earth’s magnetosphere – including the Magnetospheric Multiscale mission, Van Allen Probes, and Time History of Events and Macroscale Interactions during Substorms (also known as THEMIS) – along with a host of other satellites that study other aspects of the sun-Earth connection.

Mercury, with a substantial iron-rich core, has a magnetic field that is only about 1% as strong as Earth’s. It is thought that the planet’s magnetosphere is stifled by the intense solar wind, limiting its strength, although even without this effect, it still would not be as strong as Earth’s. The MESSENGER satellite orbited Mercury from 2011 to 2015, helping us understand our tiny terrestrial neighbor.

After the sun, Jupiter has by far the biggest magnetosphere in our solar system – it stretches about 12 million miles from east to west, almost 15 times the width of the sun. (Earth’s, on the other hand, could easily fit inside the sun.) Jupiter does not have a molten metal core like Earth; instead, its magnetic field is created by a core of compressed liquid metallic hydrogen.

One of Jupiter’s moons, Io, has intense volcanic activity that spews particles into Jupiter’s magnetosphere. These particles create intense radiation belts and the large auroras around Jupiter’s poles.

Ganymede, Jupiter’s largest moon, also has its own magnetic field and magnetosphere – making it the only moon with one. Its weak field, nestled in Jupiter’s enormous shell, scarcely ruffles the planet’s magnetic field.

Our Juno mission orbits inside the Jovian magnetosphere sending back observations so we can better understand this region. Previous observations have been received from Pioneers 10 and 11, Voyagers 1 and 2, Ulysses, Galileo and Cassini in their flybys and orbits around Jupiter.

Saturn’s moon Enceladus transforms the shape of its magnetosphere. Active geysers on the moon’s south pole eject oxygen and water molecules into the space around the planet. These particles, much like Io’s volcanic emissions at Jupiter, generate the auroras around the planet’s poles. Our Cassini mission studies Saturn’s magnetic field and auroras, as well as its moon Enceladus.

Uranus’ magnetosphere wasn’t discovered until 1986 when data from Voyager 2’s flyby revealed weak, variable radio emissions. Uranus’ magnetic field and rotation axis are out of alignment by 59 degrees, unlike Earth’s, whose magnetic field and rotation axis differ by only 11 degrees. On top of that, the magnetic field axis does not go through the center of the planet, so the strength of the magnetic field varies dramatically across the surface. This misalignment also means that Uranus’ magnetotail – the part of the magnetosphere that trails away from the sun – is twisted into a long corkscrew.

Neptune’s magnetosphere is also tilted from its rotation axis, but only by 47. Just like on Uranus, Neptune’s magnetic field strength varies across the planet. This also means that auroras can be seen away from the planet’s poles – not just at high latitudes, like on Earth, Jupiter and Saturn.

Does Every Planet Have a Magnetosphere?

Neither Venus nor Mars have global magnetic fields, although the interaction of the solar wind with their atmospheres does produce what scientists call an “induced magnetosphere.” Around these planets, the atmosphere deflects the solar wind particles, causing the solar wind’s magnetic field to wrap around the planet in a shape similar to Earth’s magnetosphere.

What About Beyond Our Solar System?

Outside of our solar system, auroras, which indicate the presence of a magnetosphere, have been spotted on brown dwarfs – objects that are bigger than planets but smaller than stars.

There’s also evidence to suggest that some giant exoplanets have magnetospheres. As scientists now believe that Earth’s protective magnetosphere was essential for the development of conditions friendly to life, finding magnetospheres around exoplanets is a big step in finding habitable worlds.  

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The surface of Jupiter imaged during a flyby from NASA’s Juno Spacecraft

System Solar

Chasing Storms at 17,500mph

Flying 250 miles above the Earth aboard the International Space Station has given me the unique vantage point from which to view our planet. Spending a year in space has given me the unique opportunity to see a wide range of spectacular storm systems in space and on Earth. 

The recent blizzard was remarkably visible from space. I took several photos of the first big storm system on Earth of year 2016 as it moved across the East Coast, Chicago and Washington D.C. Since my time here on the space station began in March 2015, I’ve been able to capture an array of storms on Earth and in space, ranging from hurricanes and dust storms to solar storms and most recently a rare thunder snowstorm.

Blizzard 2016

Hurricane Patricia 2015

Hurricane Joaquin 2015

Dust Storm in the Red Sea 2015

Dust Storm of Gobi Desert 2015

Aurora Solar Storm 2015

Aurora Solar Storm 2016

Thunderstorm over Italy 2015

Lightning and Aurora 2016

Rare Thunder Snowstorm 2016

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Image of Saturn taken by Cassini spacecraft in October 28, 2016.

Credit: NASA / JPL / Cassini

Largest Batch of Earth-size, Habitable Zone Planets

Our Spitzer Space Telescope has revealed the first known system of seven Earth-size planets around a single star. Three of these planets are firmly located in an area called the habitable zone, where liquid water is most likely to exist on a rocky planet.

This exoplanet system is called TRAPPIST-1, named for The Transiting Planets and Planetesimals Small Telescope (TRAPPIST) in Chile. In May 2016, researchers using TRAPPIST announced they had discovered three planets in the system.

Assisted by several ground-based telescopes, Spitzer confirmed the existence of two of these planets and discovered five additional ones, increasing the number of known planets in the system to seven.

This is the FIRST time three terrestrial planets have been found in the habitable zone of a star, and this is the FIRST time we have been able to measure both the masses and the radius for habitable zone Earth-sized planets.

All of these seven planets could have liquid water, key to life as we know it, under the right atmospheric conditions, but the chances are highest with the three in the habitable zone.

At about 40 light-years (235 trillion miles) from Earth, the system of planets is relatively close to us, in the constellation Aquarius. Because they are located outside of our solar system, these planets are scientifically known as exoplanets. To clarify, exoplanets are planets outside our solar system that orbit a sun-like star.

In this animation, you can see the planets orbiting the star, with the green area representing the famous habitable zone, defined as the range of distance to the star for which an Earth-like planet is the most likely to harbor abundant liquid water on its surface. Planets e, f and g fall in the habitable zone of the star.

Using Spitzer data, the team precisely measured the sizes of the seven planets and developed first estimates of the masses of six of them. The mass of the seventh and farthest exoplanet has not yet been estimated.

For comparison…if our sun was the size of a basketball, the TRAPPIST-1 star would be the size of a golf ball.

Based on their densities, all of the TRAPPIST-1 planets are likely to be rocky. Further observations will not only help determine whether they are rich in water, but also possibly reveal whether any could have liquid water on their surfaces.

The sun at the center of this system is classified as an ultra-cool dwarf and is so cool that liquid water could survive on planets orbiting very close to it, closer than is possible on planets in our solar system. All seven of the TRAPPIST-1 planetary orbits are closer to their host star than Mercury is to our sun.

 The planets also are very close to each other. How close? Well, if a person was standing on one of the planet’s surface, they could gaze up and potentially see geological features or clouds of neighboring worlds, which would sometimes appear larger than the moon in Earth’s sky.

The planets may also be tidally-locked to their star, which means the same side of the planet is always facing the star, therefore each side is either perpetual day or night. This could mean they have weather patterns totally unlike those on Earth, such as strong wind blowing from the day side to the night side, and extreme temperature changes.

Because most TRAPPIST-1 planets are likely to be rocky, and they are very close to one another, scientists view the Galilean moons of Jupiter – lo, Europa, Callisto, Ganymede – as good comparisons in our solar system. All of these moons are also tidally locked to Jupiter. The TRAPPIST-1 star is only slightly wider than Jupiter, yet much warmer. 

How Did the Spitzer Space Telescope Detect this System?

Spitzer, an infrared telescope that trails Earth as it orbits the sun, was well-suited for studying TRAPPIST-1 because the star glows brightest in infrared light, whose wavelengths are longer than the eye can see. Spitzer is uniquely positioned in its orbit to observe enough crossing (aka transits) of the planets in front of the host star to reveal the complex architecture of the system. 

Every time a planet passes by, or transits, a star, it blocks out some light. Spitzer measured the dips in light and based on how big the dip, you can determine the size of the planet. The timing of the transits tells you how long it takes for the planet to orbit the star.

The TRAPPIST-1 system provides one of the best opportunities in the next decade to study the atmospheres around Earth-size planets. Spitzer, Hubble and Kepler will help astronomers plan for follow-up studies using our upcoming James Webb Space Telescope, launching in 2018. With much greater sensitivity, Webb will be able to detect the chemical fingerprints of water, methane, oxygen, ozone and other components of a planet’s atmosphere.

At 40 light-years away, humans won’t be visiting this system in person anytime soon…that said…this poster can help us imagine what it would be like: 

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

The South Pole, Jupiter

Europa and Io over Jupiter.

Enceladus, moon of Saturn, observed by the Cassini space probe on December 19, 2015. (NASA)

Space Shuttle Endeavour mounted atop one of NASA’s modified Boeing 747 Shuttle Carrier Aircraft.

February 19, 2010 – The Space Shuttle Endeavour as seen  from the ISS after undocking. (NASA)

The last shuttle