Category: orbit



Jupiter’s vibrant bands of light belts and dar…

Jupiter’s vibrant bands of light belts and dark regions appear primed for their close-up during our Juno spacecraft’s 10th flyby on Feb. 7. This flyby was a gravity science positioned pass. During orbits that highlight gravity experiments, Juno is positioned toward Earth in a way that allows both transmitters to downlink data in real-time to one of the antennas of our Deep Space Network. All of Juno’s science instruments and the spacecraft’s JunoCam were in operation during the flyby, collecting data that is now being returned to Earth. The science behind this beautifully choreographed image will help us understand the origin and structure of the planet beneath those lush, swirling clouds.

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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 our 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 


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 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, occuring 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 a push 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


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.

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

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Bruce McCandless II (June 8, 1937 – December 2…

Bruce McCandless II (June 8, 1937 – December 21, 2017)

Rest In Peace



Chasing the Shadow of Neptune’s Moon Triton

Our Flying Observatory


Our flying observatory, called SOFIA, carries a 100-inch telescope inside a Boeing 747SP aircraft. Scientists onboard study the life cycle of stars, planets (including the atmosphere of Mars and Jupiter), nearby planetary systems, galaxies, black holes and complex molecules in space.

AND in just a few days SOFIA is going on a special flight to chase the shadow of Neptune’s moon Triton as it crosses Earth’s surface!

In case you’re wondering, SOFIA stands for: Stratospheric Observatory for Infrared Astronomy.



Triton is 1,680 miles (2,700 km) across, making it the largest of the 13 moons orbiting Neptune. Unlike most large moons in our solar system, Triton orbits in the opposite direction of Neptune, called a retrograde orbit. This backward orbit leads scientists to believe that Triton formed in an area past Neptune, called the Kuiper Belt, and was pulled into its orbit around Neptune by gravity. 

The Voyager 2 spacecraft flew past Neptune and Triton in 1989 and found that Triton’s atmosphere is made up of mostly nitrogen…but it has not been studied in nearly 16 years!

Occultations are Eclipse-Like Events


An occultation occurs when an object, like a planet or a moon, passes in front of a star and completely blocks the light from that star. As the object blocks the star’s light, it casts a faint shadow on Earth’s surface

But unlike an eclipse, these shadows are not usually visible to the naked eye because the star and object are much smaller and not nearly as bright as our sun. Telescopes with special instruments can actually see these shadows and study the star’s light as it passes near and around the object – if they can be in the right place on Earth to catch the shadow.

Chasing Shadows


Scientists have been making advanced observations of Triton and a background star. They’ve calculated exactly where Triton’s faint shadow will fall on Earth! Our SOFIA team has designed a flight path that will put SOFIA (the telescope and aircraft) exactly in the center of the shadow at the precise moment that Triton and the star will align. 

This is no easy feat because the shadow is moving at more than 53,000 mph while SOFIA flies at Mach 0.85 (652 mph), so we only have about two minutes to catch the shadow!! But our SOFIA team has previously harnessed the aircraft’s mobility to study Pluto from inside the center of its occultation shadow, and is ready to do it again to study Triton!

What We Learn From Inside the Shadow


From inside the shadow, our team on SOFIA will study the star’s light as it passes around and through Triton’s atmosphere. This allows us to learn more about Triton’s atmosphere, including its temperature, pressure, density and composition! 

Our team will use this information to examine if Triton’s atmosphere has changed since our Voyager 2 spacecraft flew past it in 1989. That’s a lot of information from a bit of light inside a shadow! Similar observations of Uranus in 1977, from our previous flying observatory, led to the discovery of rings around that planet!

International Ground-Based Support


Ground-based telescopes across the United States and Europe – from Scotland to the Canary Islands – will also be studying Triton’s occultation. Even though most of these telescopes will not be in the center of the shadow, the simultaneous observations, from different locations on Earth, will give us information about how Triton’s atmosphere varies across its latitudes. 

This data from across the Earth and from onboard SOFIA will help researchers understand how Triton’s atmosphere is distorted at different locations by its high winds and its strong tides!

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The total solar eclipse is coming! Here’s your chance to ask an…

The total solar eclipse is coming! Here’s your chance to ask an eclipse scientist your questions!

Have questions about the upcoming total solar eclipse on August 21? Join our Tumblr Answer Time session on Thursday, August 17 from 3:00 – 4:00 p.m. EDT/12:00 – 1:00 p.m. PDT. here on NASA’s Tumblr, where space physics researcher Alexa Halford will answer them. Make sure to ask your questions now by visiting:!

Alexa Halford is a space physics researcher at our Goddard Space Flight Center and Dartmouth College. She started researching waves in Earth’s magnetosphere as an undergraduate at Augsburg College with Mark Engebretson using ground based magnetometers in the Arctic and Antarctic. She moved away from waves to focus on geomagnetic storms and substorms during her masters at the University of Colorado Boulder with Dan Baker but returned once more to waves with her PhD at University of Newcastle NSW Australia. Her PhD thesis was on Electromagnetic Ion Cyclotron (EMIC) waves during the CRRES mission and their relationship to the plasmasphere and radiation belts.

She is member of the scientific team for a NASA-funded scientific balloon experiment project called BARREL (Balloon Array for RBSP Relativistic Electron Losses) where she looks at the population of particles lost due to these interactions. She is now currently a contractor at NASA Goddard continuing work the BARREL and NASA Van Allen Probes satellite missions.

To get more information about the eclipse, visit:

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Our pale blue dot, planet Earth, is seen in this video captured…

Our pale blue dot, planet Earth, is seen in this video captured by NASA astronaut Jack Fischer from his unique vantage point on the International Space Station. From 250 miles above our home planet, this time-lapse imagery takes us over the Pacific Ocean’s moon glint and above the night lights of San Francisco, CA. The thin hue of our atmosphere is visible surrounding our planet with a majestic white layer of clouds sporadically seen underneath.

The International Space Station is currently home to 6 people who are living and working in microgravity. As it orbits our planet at 17,500 miles per hour, the crew onboard is conducting important research that benefits life here on Earth.

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Freaky fast and really awesome! NASA astronaut Jack Fischer…

Freaky fast and really awesome! NASA astronaut Jack Fischer posted this GIF to his social media Tuesday saying, “I was checking the view out the back window & decided to take a pic so you can see proof of our ludicrous speed! #SpaceIsAwesome”.

In case you didn’t know, the International Space Station travels 17,500 miles per hour as it orbits 250 miles above the Earth.

Currently, three humans are living and working there, conducting important science and research. The orbiting laboratory is home to more than 250 experiments, including some that are helping us determine the effects of microgravity on the human body. Research on the station will not only help us send humans deeper into space than ever before, including to Mars, but also benefits life here on Earth.

Follow NASA astronaut Jack Fischer on Instagram and Twitter

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Five Ways the International Space Station’s National Lab Enables Commercial Research

A growing number of commercial partners use the International Space Station National Lab. With that growth, we will see more discoveries in fundamental and applied research that could improve life on the ground.


Space Station astronaut Kate Rubins was the first person to sequence DNA in microgravity.

Since 2011, when we engaged the Center for the Advancement of Science in Space (CASIS) to manage the International Space Station (ISS) National Lab, CASIS has partnered with academic researchers, other government organizations, startups and major commercial companies to take advantage of the unique microgravity lab. Today, more than 50 percent of CASIS’ experiments on the station represent commercial research.

Here’s a look at five ways the ISS National Lab is enabling new opportunities for commercial research in space.

1. Supporting Commercial Life Sciences Research


One of the main areas of focus for us in the early origins of the space station program was life sciences, and it is still a major priority today. Studying the effects of microgravity on astronauts provides insight into human physiology, and how it evolves or erodes in space. CASIS took this knowledge and began robust outreach to the pharmaceutical community, which could now take advantage of the microgravity environment on the ISS National Lab to develop and enhance therapies for patients on Earth. Companies such as Merck, Eli Lilly & Company, and Novartis have sent several experiments to the station, including investigations aimed at studying diseases such as osteoporosis, and examining ways to enhance drug tablets for increased potency to help patients on Earth. These companies are trailblazers for many other life science companies that are looking at how the ISS National Lab can advance their research efforts.

2. Enabling Commercial Investigations in Material and Physical Sciences


Over the past few years, CASIS and the ISS National Lab also have seen a major push toward material and physical sciences research by companies interested in enhancing their products for consumers. Examples range from Proctor and Gamble’s investigation aimed at increasing the longevity of daily household products, to Milliken’s flame-retardant textile investigation to improve protective clothing for individuals in harm’s way, and companies looking to enhance materials for household appliances. Additionally, CASIS has been working with a variety of companies to improve remote sensing capabilities in order to better monitor our oceans, predict harmful algal blooms, and ultimately, to better understand our planet from a vantage point roughly 250 miles above Earth.

3. Supporting Startup Companies Interested in Microgravity Research 


CASIS has funded a variety of investigations with small startup companies (in particular through seed funding and grant funding from partnerships and funded solicitations) to leverage the ISS National Lab for both research and test-validation model experiments. CASIS and The Boeing Company recently partnered with MassChallenge, the largest startup accelerator in the world, to fund three startup companies to conduct microgravity research.

4. Enabling Validation of Low-Earth Orbit Business Models 


The ISS National Lab helps validate low-Earth orbit business models. Companies such as NanoRacks, Space Tango, Made In Space, Techshot, and Controlled Dynamics either have been funded by CASIS or have sent instruments to the ISS National Lab that the research community can use, and that open new channels for inquiry. This has allowed the companies that operate these facilities to validate their business models, while also building for the future beyond station.

5. Demonstrating the Commercial Value of Space-based Research

We have been a key partner in working with CASIS to demonstrate to American businesses the value of conducting research in space. Through outreach events such as our Destination Station, where representatives from the International Space Station Program Science Office and CASIS select cities with several major companies and meet with the companies to discuss how they could benefit from space-based research. Over the past few years, this outreach has proven to be a terrific example of building awareness on the benefits of microgravity research.

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