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Best everyday stretches that will help you stay flexible and fit at any age

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When the Moon's Shadow Falls on Earth

On July 2, 2019, a total solar eclipse will pass over parts of Argentina and Chile.

Solar eclipses happen when the Moon passes directly between the Sun and Earth, casting its shadow onto Earth’s surface. Because the Moon’s orbit isn’t perfectly in line with the Sun and Earth, its shadow usually passes above or below Earth. But when it lines up just right, we get a solar eclipse!

People in the inner part of the Moon’s shadow — the umbra — have the chance to witness a total solar eclipse, while those in the outer part of the shadow — the penumbra — experience a partial solar eclipse.

The path of the total solar eclipse stretches across parts of Chile and Argentina. People outside this path may see a partial eclipse or no eclipse at all.

During a total solar eclipse, the Moon blocks out the Sun’s bright face, revealing its comparatively faint outer atmosphere, the corona. The corona is a dynamic region that is thought to hold the answers to questions about the fundamental physics of the Sun — like why the corona is so much hotter than the Sun’s surface and how the Sun’s constant outflow of material, the solar wind, is accelerated to such high speeds. 

Our Parker Solar Probe and the upcoming Solar Orbiter mission from the European Space Agency are exploring these questions by flying through the corona itself and taking unprecedented measurements of the conditions there. Plus, our newly-chosen PUNCH mission will create tiny, artificial eclipses in front of its cameras — using an instrument called a coronagraph — to study structures in the Sun’s corona and examine how it generates the solar wind.

Watching the eclipse

It’s never safe to look directly at the uneclipsed or partially eclipsed Sun – so you’ll need special

solar viewing glasses

or an indirect viewing method, like

pinhole projection

, to watch the eclipse. 

For people in the path of totality, there will be a few brief moments when it is safe to look directly at the eclipse. Only once the Moon has completely covered the Sun and there is no sunlight shining is it safe to look at the eclipse. Make sure you put your eclipse glasses back on or return to indirect viewing before the first flash of sunlight appears around the Moon’s edge.

No matter where you are, you can watch the eclipse online! The Exploratorium will be streaming live views of the eclipse with commentary in both English and Spanish starting at 4 p.m. EDT / 1 p.m. PDT on July 2. Watch with us at nasa.gov/live!

Para más información e actualizaciones en español acerca del eclipse, sigue a @NASA_es en Twitter o vea esta hoja de hechos.

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

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They Put a Flag on the Moon

It’s 1969 and Apollo 11 astronauts Buzz Aldrin and Neil Armstrong are the first humans to land on the Moon. In now iconic footage, Aldrin and Armstrong carefully assemble and maneuver an American flag to place on the lunar surface. The fabric unfurls, staying suspended without any wind to animate the stars and stripes. The flagpole sways precariously as the crew work to anchor it in the Moon’s low gravity at just 1/6th that of Earth’s. How did this moment come about? On Flag Day, let’s dive behind-the-scenes of what led to getting the American flag on the Moon 50 years ago.

Image: Astronaut Buzz Aldrin poses for a photograph beside the deployed United States flag during the Apollo 11 mission.

Seeking to empower the nation, President John F. Kennedy gave us a grand charge. The human spaceflight program of the early 1960s was challenged to work on missions that sent humans to the surface of another world. Following President Kennedy’s death in 1963, President Richard Nixon stressed a more international perspective to the Apollo missions. To reconcile the need for global diplomacy with national interests, we appointed the Committee on Symbolic Activities for the First Lunar Landing.

Image: NASA Administrator Thomas Paine and President Richard Nixon are seen aboard the USS Hornet, Apollo 11’s splashdown recovery vessel.

The committee, and the U.S. at large, wanted to avoid violating the United Nations Outer Space Treaty, which prohibited any nation from taking possession of a celestial body. After some debate, they recommended that the flag only appear during the Apollo 11 spacewalk. A plaque would accompany it, explaining that the flag was meant to stand for peaceful exploration, not conquest. 

Image: The plaque reads “Here men from the planet Earth first set foot upon the Moon July 1969 A.D. We came in peace for all of mankind.” Under the text are signatures by President Nixon, Buzz Aldrin, Neil Armstrong, and Michael Collins.

A team of engineers at Johnson Space Center had three months to resolve several issues regarding the flag’s assembly. First, was the Moon’s lack of atmosphere. The flag, quite literally, could not fly the way it does on Earth. To address this, a horizontal crossbar was added to support the flag’s weight and give the illusion of it waving.

Image: NASA technician David L. McCraw shows the flag next to a Lunar Module mockup.

Second was the flag’s assembly, which had to be as lightweight and compact as possible so as not to take up limited storage space. The completed package, which was attached to Lunar Module’s ladder, weighed just under ten pounds. It received an outer case made of steel, aluminum, and Thermoflex insulation and blanketing to shield the flag from the 2,000 degree Fahrenheit spike from the Eagle’s descent engine.

Image: Component pieces of the flag assembly.

The last issue was mobility. Bulky spacesuits significantly restricted the astronauts’ range of motion, and suit pressurization limited how much force they could apply. To accommodate these limits, the team included telescoping components to minimize the need to reach and maneuver the poles. A red painted ring on the flagpole indicated how far into the ground it should be driven. Hinges and catches would lock into place once the pieces were fully extended.

Image: Diagram from the 1969 Apollo 11 press release illustrating astronaut spacesuit reach capabilities and ideal working height.

Fifty years after Apollo 11, the flag we planted on the lunar surface has likely faded but its presence looms large in United States history as a symbol of American progress and innovation.

Image: A close-up view of the U.S. flag deployed on the Moon at the Taurus-by the crew of Apollo 17, the most recent lunar landing mission.

The story doesn’t stop here. Anne Platoff’s article “Where No Flag Has Gone Before” sheds more light on the context and technical process of putting the United States flag on the Moon. You can also check out Johnson Space Center’s recent feature story that details its presence in later missions. Happy Flag Day!  Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.

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Resting moment. @

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Memory you in my mind.

June 7th 1954: Alan Turing dies

On this day in 1954, the British mathematician and scientist Alan Turing died. Turing is considered the father of computer science and artificial intelligence with his invention of the ‘Turing machine’ - a precursor to the modern computer. He was also a crucial part of England’s code breaking team at Bletchley Park during World War Two, developing ways to interpret German messages from the Enigma machine. The work of Turing and his fellow code breakers was a great boost to the Allied war effort, supposedly shortening the war by as many as two to four years. However, in 1952 he was arrested for homosexuality - which was still illegal in Britain - and accepted chemical castration rather than prison. Turing suffered side effects from the treatment and two years later died from cyanide poisoning, supposedly from an apple found by his bed. Whilst some claim it was accidental, an inquest determined Turing had committed suicide due to the persecution he suffered. In 2009, following a popular online petition, Prime Minister Gordon Brown issued a posthumous apology to Alan Turing.

“We’re sorry, you deserved so much better” - Gordon Brown, 2009