21 dezembro 2017

When Princess Diana died in the summer of 1997, two out of three...



When Princess Diana died in the summer of 1997, two out of three Britons said they were “upset” or “very upset” by her passing. Around 3 million came out to watch her funeral procession in the streets of London. And around the world, about 2.5 billion people watched the worldwide television coverage.

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The Science Behind The Perfect Photo

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How A Solar Eclipse Destroyed A City

Greek philosopher-historian Xenophon records that Larissa, a town on the banks of the river Tigris, somewhere in modern Iraq, had once been a well-fortified stronghold. Although it had become a deserted city by the time Xenophon saw it in 401 BCE. At its height, Larissa had 100 foot high clay brick walls, sitting on a 20 foot stone base, which encircled the entire city. Those are very tall, especially for the 600s BCE. It had proven too high for the Persian army. They had repeatedly tried, and failed, to take Larissa about 200 years before, according to Xenophon.

But then the heavens intervened. “A cloud covered up the sun and hid it from sight” Xenophon wrote. The Larissans, terrified, abandoned their city. Some hid on a pyramid nearby. Others simply fled. Larissa was left without defenders, and the Persians easily captured the city, although it probably wasn’t worth much without any inhabitants.

The track of the total eclipse which happened on May 19, 557 BCE, passed through southern Syria and Iraq. This may have been the astronomical event that Xenophon wrote about, 150 years later.

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Launch Day!


On Dec. 21, 1968, the Apollo 8 crew leaves the Kennedy Space Center's then-named Manned Spacecraft Operations Building during the mission's prelaunch countdown on the way to their history-making lunar orbiting flight.

from NASA http://ift.tt/2zbwlJX
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Happy Cognitive Dissonance Day

Happy Cognitive Dissonance Day:

Visit –> http://ift.tt/2z9wayu to learn about cognitive dissonance.

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Solstice Sun and Milky Way


Welcome to December's solstice, first day of winter in the north and summer for the southern hemisphere. Astronomical markers of the seasons, solstice and equinox dates are based on the Sun's place in its annual journey along the ecliptic, through planet Earth's sky. At this solstice, the Sun reaches its maximum southern declination of -23.5 degrees today at 16:28 UTC, while its right ascension coordinate on the celestial sphere is 18 hours. That puts the Sun in the constellation Sagittarius in a direction near the center of our Milky Way galaxy. In fact, if you could see today's Solstice Sun against faint background stars and nebulae (that's really hard to do, especially in the daytime ...) your view might look something like this composited panorama. To make it, images of our fair galaxy were taken under dark Namibian night skies, then stitched together in a panoramic view. From a snapshot made on December 21, 2015, the Sun was digitally overlayed as a brilliant star at today's northern winter solstice position, close to the center of the Milky Way.

from NASA http://ift.tt/2oZxZOG
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