Science & Technology - Astronomy picture of the day : HDR: Earth's Circular Shadow on the Moon

2019 July 22
HDR: Earth's Circular Shadow on the Moon 
Image Credit & Copyright: Cristian Fattinnanzi

Explanation: What could create such a large circular shadow on the Moon? The Earth. Last week's full Moon -- the Buck Moon -- was so full that it fell almost exactly in a line with the Sun and the Earth. When that happens the Earth casts its shadow onto the Moon. The circularity of the Earth's shadow on the Moon was commented on by Aristotle and so has been noticed since at least the 4th century BC. What's new is humanity's ability to record this shadow with such high dynamic range (HDR). The featured HDR composite of last week's partial lunar eclipse combines 15 images and include an exposure as short as 1/400th of a second -- so as not to overexpose the brightest part -- and an exposure that lasted five seconds -- to bring up the dimmest part. This dimmest part -- inside Earth's umbra -- is not completely dark because some light is refracted through the Earth's atmosphere onto the Moon. A total lunar eclipsewill occur next in 2021 May.

Science & Technology - Astronomy picture of the day : Moonquakes Surprisingly Common

2019 July 21
Moonquakes Surprisingly Common 
Image Credit: NASA, Apollo 11 Crew

Explanation: Why are there so many moonquakes? Analyses of seismometers left on the moon by the Apollo moon landings reveals a surprising number of moonquakes occurring within 100 kilometers of the surface. In fact, 62moonquakes were detected in data recorded between 1972 and 1977. Many of these moonquakes are not only strong enough to move furniture in a lunar apartment, but the stiff rock of the moon continues to vibrate for many minutes, significantly longer than the softer rock earthquakes on Earth. The cause of the moonquakes remains unknown, but a leading hypothesis is the collapse of underground faults. Regardless of the source, future moon dwellings need to be built to withstand the frequent shakings. Pictured here 50 years ago today, Apollo 11 astronaut Buzz Aldrin stands beside a recently deployed lunar seismometer, looking back toward the lunar landing module.

Science & Technology - Astronomy picture of the day : Tranquility Base Panorama

2019 July 18
Tranquility Base Panorama 
Image Credit: Neil Armstrong, Apollo 11, NASA

Explanation: On July 20, 1969 the Apollo 11 lunar module Eagle safely touched down on the Moon. It landed near the southwestern corner of the Moon's Mare Tranquillitatis at a landing site dubbed Tranquility Base. This panoramic view of Tranquility Base was constructed from the historic photos taken from the lunar surface. On the far left astronaut Neil Armstrong casts a long shadow with Sun is at his back and the Eagle resting about 60 meters away ( AS11-40-5961). He stands near the rim of 30 meter-diameter Little West crater seen here to the right ( AS11-40-5954). Also visible in the foreground is the top of the camera intended for taking stereo close-ups of the lunar surface.

Science & Technologie - Santé/Médecine : Eau "potable" radioactive pour des millions de personnes

268 communes françaises sont concernées, dont de "grandes agglomérations" comme Orléans, Blois, Tours, Angers, Nantes, et 122 communes d'Ile-de-France.

L'association pour le contrôle de la radioactivité dans l'Ouest (ACO) tire la sonnette d'alarme. Elle a dénoncé ce mercredi une "contamination" radioactive de l'eau potable de 6,4 millions personnes en France.

"6,4 millions de personnes sont alimentées par de l'eau contaminée au tritium" selon "des données fournies par le ministère de la Santé", affirme le laboratoire basé à Hérouville-Saint-Clair, dans l'agglomération de Caen, dans un communiqué.

L'Express - France

Science & Technology - Astronomy picture of the day : Shadowed Moon and Mountain

2019 July 18
Shadowed Moon and Mountain Image Credit: Norbert Span

Explanation: On July 16 the Moon celebrated the 50th anniversary of the launch of Apollo 11 with a lunar eclipse visible from much of planet Earth. In this view part of the lunar disk is immersed in Earth's dark, reddened umbral shadow. Near the maximum eclipse phase, it just touches down along a mountain ridge. The rugged Tyrolean nightscape was recorded after moonrise south of Innsbruck, Austria with a dramatically lit communication tower along the ridgeline. Of course eclipses rarely travel alone. This partial lunar eclipse was at the Full Moon following July 2nd's New Moon and total eclipse of the Sun.

Science & Technology - Astronomy picture of the day : Apollo 11: Descent to the Moon

2019 July 17
Apollo 11: Descent to the Moon 
Video Credit: NASA, Apollo Flight Journal Compilation & Copyright: W. David Woods

Explanation: It had never been done before. But with the words "You're Go for landing", 50 years ago this Saturday, Apollo 11 astronauts Aldrin and Armstrong were cleared to make the first try. The next few minutes would contain more than a bit of drama, as an unexpected boulder field and an unacceptably sloping crater loomed below. With fuel dwindling, Armstrong coolly rocketed the lander above the lunar surface as he looked for a clear and flat place to land. With only seconds of fuel remaining, and with the help of Aldrin and mission control calling out data, Armstrong finally found a safe spot -- and put the Eagle down. Many people on Earth listening to the live audio felt great relief on hearing "The Eagle has landed", and great pride knowing that for the first time ever, human beings were on the Moon. Combined in the featured descent video are two audio feeds, a video feed similar to what the astronauts saw, captions of the dialog, and data including the tilt of the Eagle lander. The video concludes with the panorama of the lunar landscape visible outside the Eagle. A few hours later, hundreds of millions of people across planet Earth, drawntogether as a single species, watched fellow humans walk on the Moon.

Science & Technology - Astronomy picture of the day : Eagle Aurora over Norway

2019 July 14
Eagle Aurora over Norway 
Image Credit & Copyright: Bjørn Jørgensen

Explanation: What's that in the sky? An aurora. A large coronal mass ejection occurred on our Sun five days before this 2012 image was taken, throwing a cloud of fast moving electrons, protons, and ions toward the Earth. Although most of this cloud passed above the Earth, some of it impacted our Earth's magnetosphere and resulted in spectacular auroras being seen at high northern latitudes. Featured here is a particularly photogenic auroral corona captured above Grotfjord, Norway. To some, this shimmering green glow of recombining atmospheric oxygen might appear as a large eagle, but feel free to share what it looks like to you. Although the Sun is near Solar Minimum, streams of the solar wind continue to impact the Earth and create impressive auroras visible even last week.

Music - Slides - Bob Marley : "We and dem"

"We and dem"

Science & Technology - Astronomy picture of the day : The Ghost of Jupiter's Halo

2019 July 11
The Ghost of Jupiter's Halo 
Image Credit & Copyright: CHART32 Team, Processing - Johannes Schedler / Volker Wendel

Explanation: Close-up images of NGC 3242 show the cast off shroud of a dying, sun-like star fancifully known as The Ghost of Jupiter nebula. But this deep and wide telescopic view also finds the seldom seen outer halo of the beautiful planetary nebula at the upper left, toward Milky Way stars and background galaxies in the serpentine constellation Hydra. Intense and otherwise invisible ultraviolet radiation from the nebula's central white dwarf star powers its illusive glow in visible light. In fact, planets of NGC 3242's evolved white dwarf star may have contributed to the nebula's symmetric features and shape. Activity beginning in the star's red giant phase, long before it produced a planetary nebula, is likely the cause of the fainter more extensive halo. About a light-year across NGC 3242 is some 4,500 light-years away. The tenuous clouds of glowing material at the right could well be interstellar gas, by chance close enough to the NGC 3242's white dwarf to be energized by its ultraviolet radiation.

Science & Technology - Astronomy picture of the day : Birds During a Total Solar Eclipse

2019 July 9
Birds During a Total Solar Eclipse 
Image Credit & Copyright: Leonardo Caldas

Explanation: What do birds do during a total solar eclipse? Darkness descends more quickly in a total eclipse than during sunset, but returns just as quickly -- and perhaps unexpectedly to the avians -- just a few minutes later. Stories about the unusual behavior of birds during eclipses have been told for centuries, but bird reactions were recorded and studied systematically by citizen scientists participating in an eBird project during the total solar eclipse that crossed the USA in 2017 August. Although some unusual behaviors were observed, many observers noted birds acting like it was dusk and either landing or flying low to the ground. Radar confirmed a significant decrease in high-flying birds and insects during and just after totality. Conversely, several sightings of normally nocturnal birds were reported. Pictured, a flock of birds in La Serena, Chile flew through the air together during the total solar eclipse that crossed South America last week. The photographer captured the scene in frames from an eclipse video. The next total solar eclipse in 2020 December will also cross South America, while in 2024 April a total solar eclipse will cross North Americafrom Mexico through New England, USA.