Science & Technology - Atronomy picture of the day : The Space Station Crosses a Spotless Sun

2019 October 28
The Space Station Crosses a Spotless Sun 
Image Credit & Copyright: Eduardo Schaberger Poupeau

Explanation: Typically, the International Space Station is visible only at night. Slowly drifting across the night sky as it orbits the Earth, the International Space Station (ISS) can be seen as a bright spot about once a month from many locations. The ISS is then visible only just after sunset or just before sunrise because it shines by reflected sunlight -- once the ISS enters the Earth's shadow, it will drop out of sight. The only occasion when the ISS is visible during the day is when it passes right in front of the Sun. Then, it passes so quickly that only cameras taking short exposures can visually freeze the ISS's silhouette onto the background Sun. The featured picture did exactly that -- it is actually a series of images taken a month ago from Santa Fe, Argentina with perfect timing. This image series was later combined with a separate image highlighting the texture of the spotless Sun, and an image bringing up the Sun's prominencesaround the edge. At an unusually low Solar Minimum, the Sun has gone without sunspots now for most of 2019.

Science & Technology - Astronomy picture of the day : Ghost Aurora over Canada

2019 October 27
Ghost Aurora over Canada 
Image Credit & Copyright: Yuichi Takasaka, TWAN

Explanation: What does this aurora look like to you? While braving the cold to watch the skies above northern Canada early one morning in 2013, a most unusual aurora appeared. The aurora definitely appeared to be shaped likesomething , but what? Two ghostly possibilities recorded by the astrophotographer were "witch" and "goddess of dawn", but please feel free to suggest your own Halloween-enhanced impressions. Regardless of fantastical pareidolicinterpretations, the pictured aurora had a typical green color and was surely caused by the scientifically commonplace action of high energy particles from space interacting with oxygen in Earth's upper atmosphere. In the image foreground, at the bottom, is a frozen Alexandra Falls, while evergreen trees cross the middle.

Science & Technology - Astronomy picture of the day : Gravity's Grin

2019 October 26
Gravity's Grin 
Image Credit: X-ray - NASA / CXC / J. Irwin et al. ; Optical - NASA/STScI 

Explanation: Albert Einstein's general theory of relativity, published over 100 years ago, predicted the phenomenon of gravitational lensing. And that's what gives these distant galaxies such a whimsical appearance, seen through the looking glass of X-ray and optical image data from the Chandra and Hubble space telescopes. Nicknamed the Cheshire Cat galaxy group, the group's two large elliptical galaxies are suggestively framed by arcs. The arcs are optical images of distant background galaxies lensed by the foreground group's total distribution of gravitational mass. Of course, that gravitational mass is dominated by dark matter. The two large elliptical "eye" galaxies represent the brightest members of their own galaxy groups which are merging. Their relative collisional speed of nearly 1,350 kilometers/second heats gas to millions of degrees producing the X-ray glow shown in purple hues. Curiouser about galaxy group mergers? The Cheshire Cat group grins in the constellation Ursa Major, some 4.6 billion light-years away.

Science & Technologie - Santé et médecine : "Cancer l'espoir"

Je pense que le plus important est de garder espoir, tant que des traitements sont possibles. Il y a 2 ans, on a découvert chez mon mari ,un cancer du poumon, carcinome stade 4 avec des métastases sur la colonne vertébrale et le foie. Il a suivi 2 cures de 5 séances de chimio très dures + de la radiothérapie au niveau de la colonne, tout cela pendant un an et demi. Il y a 4 mois, les médecins ont arrêté tous les traitements,(son organisme était épuisé) malgré des traces visibles au scanner. Ces jours-ci, mon mari va de mieux en mieux, a retrouvé son poids normal, ne boîte plus, n'a plus toutes ces horribles douleurs qui lui provoquaient des insomnies. La semaine dernière, il a subi un scanner qui a montré que son état était très stable, qu'il était en début de rémission. Un grand merci à son médecin qui a toujours eu une attitude positive sans se prononcer sur ses chances de vivre. Elle nous a expliqué que plusieurs types de traitements existaient pour son cas alors il fallait garder espoir et qu'il fallait se battre, que le mental a une part importante dans la guérison. Aujourd'hui, il est tôt pour dire s'il est définitivement sorti d'affaire mais on s'en moque, nous, on y croit dur comme fer ! On profite de la vie, on adopte un esprit positif en toutes circonstances, on ne se prend plus la tête pour des broutilles, on voyage beaucoup, on fait beaucoup de projets pour le futur comme si de rien n'était...

Key

Science & Technology - Astronomy picture of the day : A Mercury Transit Music Video from SDO

2019 October 21
A Mercury Transit Music Video from SDO 
Video Credit: NASA's Goddard Space Flight Center, Genna Duberstein; Music: Encompass by Mark Petrie

Explanation: What's that small black dot moving across the Sun? Mercury. Possibly the clearest view of Mercury crossing in front of the Sun in 2016 May was from Earth orbit. The Solar Dynamics Observatory obtained an uninterrupted vista recording it not only in optical light but also in bands of ultraviolet light. Featured here is a composite movie of the crossing set to music. Although the event might prove successful scientifically for better determining components of Mercury' ultra-thin atmosphere, the event surely proved successful culturally by involving people throughout the world in observing a rare astronomical phenomenon. Many spectacular images of this Mercury transit from around (and above) the globe were proudly displayed. The next transit of Mercury will take place in three weeks: on 2019 November 11.

Science & Technology - Astronomy picture of the day : Pluto at Night

2019 October 20
Pluto at Night 
Image Credit: NASA, Johns Hopkins Univ./APL, Southwest Research Institute 

Explanation: The night side of Pluto spans this shadowy scene, a stunning spacebased view with the Sun 4.9 billion kilometers (almost 4.5 light-hours) behind the dim and distant world. It was captured by far flung New Horizons in July of 2015. The spacecraft was at a range of some 21,000 kilometers from Pluto, about 19 minutes after its closest approach. A denizen of the Kuiper Belt in dramatic silhouette, the image also reveals Pluto's tenuous, surprisinglycomplex layers of hazy atmosphere. The crescent twilight landscape near the top of the frame includes southern areas of nitrogen ice plains now formally known as Sputnik Planitia and rugged mountains of water-ice in the Norgay Montes.

Science & Technology - Astronomy picture of the day : All Female Spacewalk Repairs Space Station

2019 October 19
All Female Spacewalk Repairs Space Station 
Image Credit: NASA TV, Expedition 61

Explanation: The failed unit was beyond the reach of the robotic Canadarm2. Therefore, this repair of the International Space Station would require humans. The humans on duty were NASA's Jessica Meir and Christina Koch. This was the fourth spacewalk for Meir, the first for Koch, and the first all-female spacewalk in human history. The first woman to walk in space was Svetlana Savitskaya in 1984. Koch (red stripe) and Weir are pictured hard at work on the P6 Truss, with solar panels and the darkness of space in the background. Working over seven hours, the newly installed Battery Charge / Discharge Unit (BCDU) was successfully replaced and, when powered up, operated normally.

Science & Technology - Astronomy picture of the day - BHB2007: A Baby Binary Star in Formation

2019 October 16
BHB2007: A Baby Binary Star in Formation 
Image Credit: ALMA (ESO/NAOJ/NRAO), F. O. Alves et al.

Explanation: How do binary stars form? To help find out, ESO's Atacama Large Millimeter Array (ALMA) recently captured one of the highest resolution images yet taken of a binary star system in formation. Most stars are not alone -- they typically form as part of a multiple star systems where star each orbits a common center of gravity. The two bright spots in the featured image are small disks that surround the forming proto-stars in [BHB2007] 11, while the surrounding pretzel-shaped filaments are gas and dust that have been gravitationally pulled from a larger disk. The circumstellar filaments span roughly the radius of the orbit of Neptune. The BHB2007 system is a small part of the Pipe Nebula (also known as Barnard 59), a photogenic network of dust and gas that protrudes from Milky Way's spiral disk in the constellation of Ophiuchus. The binary star formation process should be complete within a few million years.

Fotografia - "Pace e amore"

"Pace e amore"

Science & Technology - Astronomy picture of the day : MyCn 18: The Engraved Hourglass Planetary Nebula

2019 September 29
MyCn 18: The Engraved Hourglass Planetary Nebula Image Credit: NASA, ESA, Hubble; Processing & License: Judy Schmidt

Explanation: Do you see the hourglass shape -- or does it see you? If you can picture it, the rings of MyCn 18 trace the outline of an hourglass -- although one with an unusual eye in its center. Either way, the sands of time are running out for the central star of this hourglass-shaped planetary nebula. With its nuclear fuel exhausted, this brief, spectacular, closing phase of a Sun-like star's life occurs as its outer layers are ejected - its core becoming a cooling, fadingwhite dwarf. In 1995, astronomers used the Hubble Space Telescope (HST) to make a series of images of planetary nebulae, including the one featured here. Pictured, delicate rings of colorful glowing gas (nitrogen-red, hydrogen-green, and oxygen-blue) outline the tenuous walls of the hourglass. The unprecedented sharpness of the Hubble images has revealed surprising details of the nebula ejection process that are helping to resolve the outstanding mysteries of the complex shapes and symmetries of planetary nebulas like MyCn 18.