ASTRONOMY - Charon Flyover from New Horizons

 2025 May 19

Charon Flyover from New Horizons

Video Credit: NASA, JHUAPL, SwRI, P. Schenk & J. Blackwell (LPI); Music: Juicy by ALBIS

Explanation: What if you could fly over Pluto's moon Charon -- what might you see? The New Horizons spacecraft did just this in 2015 July as it zipped past Pluto and Charon with cameras blazing. The images recorded allowed for a digital reconstruction of much of Charon's surface, further enabling the creation of fictitious flights over Charon created from this data. One such fanciful, minute-long, time-lapse video is shown here with vertical heights and colors of surface features digitally enhanced. Your journey begins over a wide chasm that divides different types of Charon's landscapes, a chasm that might have formed when Charon froze through. You soon turn north and fly over a colorful depression dubbed Mordor that, one hypothesis holds, is an unusual remnant from an ancient impact. Your voyage continues over an alien landscape rich with never-before-seen craters, mountains, and crevices. The robotic New Horizons spacecraft has too much momentum to ever return to Pluto and Charon and is now headed out of our Solar System.

SANTé/MEDECINE - L'ADN des bactéries -

L'ADN d'une bactérie bien connue (Escherichia coli) est ici observé avec un grossissement fois 10.000. Étant donné la longueur du brin d'ADN, le génome de la bactérie est, en temps normal, bien compacté pour tenir dans l'espace confiné que lui offre la cellule, comme c'est le cas sur cette photo. Cependant, il arrive parfois que l'ADN soit expulsé de la cellule à la suite d'un choc osmotique.

© Eric Erbe, Wikimedia Commons, DP

LA TERRE VUE DU CIEL - Le printemps du lac Baïkal

Cette image prise par le satellite Aqua de la Nasa montre la fonte de la glace qui recouvre le lac Baïkal en Russie orientale. Le phénomène de décongélation débute vers la fin avril. Comme on peut le voir sur ces images prises début mai en 2012, la fonte est déjà très étendue dans la partie centrale du lac tandis que la zone nord reste encore prise par la glace. La zone à l'extrême sud est l'une des dernières à dégeler en raison de sa faible profondeur et ce n'est pas avant la fin juin que le lac Baïkal est totalement libéré.

© Nasa

ASTRONOMY - Pluto Flyover from New Horizons

2025 May 18

Pluto Flyover from New Horizons
Video Credit: NASA, JHUAPL, SwRI, P. Schenk & J. Blackwell (LPI); Music Open Sea Morning by Puddle of Infinity

Explanation: What if you could fly over Pluto -- what might you see? The New Horizons spacecraft did just this in 2015 July as it shot past the distant world at a speed of about 80,000 kilometers per hour. Images from this spectacular passage have been color enhanced, vertically scaled, and digitally combined into the featured two-minute time-lapse video. As your journey begins, light dawns on mountains thought to be composed of water ice but colored by frozen nitrogen. Soon, to your right, you see a flat sea of mostly solid nitrogen that has segmented into strange polygons that are thought to have bubbled up from a comparatively warm interior. Craters and ice mountains are common sights below. The video dims and ends over terrain dubbed bladed because it shows 500-meter high ridges separated by kilometer-sized gaps. The robotic New Horizons spacecraft has too much momentum to ever return to Pluto and is now headed out of our Solar System.

ASTRONOMY - Messier 101

 2025 May 16

Messier 101
Image Credit: NASA, ESA, CFHT, NOAO;
Acknowledgement - K.Kuntz (GSFC), F.Bresolin (U.Hawaii), J.Trauger (JPL), J.Mould (NOAO), Y.-H.Chu (U. Illinois)

Explanation: Big, beautiful spiral galaxy M101 is one of the last entries in Charles Messier's famous catalog, but definitely not one of the least. About 170,000 light-years across, this galaxy is enormous, almost twice the size of our own Milky Way. M101 was also one of the original spiral nebulae observed by Lord Rosse's large 19th century telescope, the Leviathan of Parsontown. Assembled from 51 exposures recorded by the Hubble Space Telescope in the 20th and 21st centuries, with additional data from ground based telescopes, this mosaic spans about 40,000 light-years across the central region of M101 in one of the highest definition spiral galaxy portraits ever released from Hubble. The sharp image shows stunning features of the galaxy's face-on disk of stars and dust along with background galaxies, some visible right through M101 itself. Also known as the Pinwheel Galaxy, M101 lies within the boundaries of the northern constellation Ursa Major, about 25 million light-years away.

SANTé/MEDECINE - ADN - Un caryotype coloré grâce à l'hybridation fluorescente (Fish)

La technique très puissante de Fish (Fluorescent In-Situ Hybridization, qui signifie hybridation in situ en fluorescence) permet de colorer les chromosomes en fonction de leur séquence grâce à des sondes fluorescentes.

Le mélange des longueurs d'onde sur une même région chromosomique entraîne une coloration particulière et typique de chaque chromosome. Cette technique permet de détecter facilement des délétions et des translocations de morceaux de chromosomes lors de la réalisation de caryotypes humains.

© Steven M. Carr

LA TERRE VUE DU CIEL - Les crêtes des monts Tian

Au sud des monts Tian, dans la province nord-ouest du Xinjiang, on peut voir une série de crêtes dont les plus hautes culminent à 1.200 mètres. Elles sont parées de strates sédimentaires de couleur rouge, verte et crème qui reflètent la formation de roches à différentes époques dans différents environnements. Les couches rouges sont des grès du Dévonien formés par d'anciennes rivières. Les couches vertes sont des grès du Silurien formés dans un océan modérément profond. Les couches de couleur crème sont du calcaire du Cambrien-Ordovicien formé dans un océan profond.

© Nasa

ASTRONOMY - A Plutonian Landscape

 2025 May 15

A Plutonian Landscape
Image Credit: NASA, Johns Hopkins Univ./APL, Southwest Research Institute

Explanation: This shadowy landscape of majestic mountains and icy plains stretches toward the horizon on a small, distant world. It was captured from a range of about 18,000 kilometers when New Horizons looked back toward Pluto, 15 minutes after the spacecraft's closest approach on July 14, 2015. The dramatic, low-angle, near-twilight scene follows rugged mountains formally known as Norgay Montes from foreground left, and Hillary Montes along the horizon, giving way to smooth Sputnik Planum at right. Layers of Pluto's tenuous atmosphere are also revealed in the backlit view. With a strangely familiar appearance, the frigid terrain likely includes ices of nitrogen and carbon monoxide with water-ice mountains rising up to 3,500 meters (11,000 feet). That's comparable in height to the majestic mountains of planet Earth. The Plutonian landscape is 380 kilometers (230 miles) across.

SANTé/MEDECINE - ADN - Les chromosomes du génome humain

L'ADN cellulaire condensé en chromosomes prend la forme d'un X, où la partie centrale charnière est appelée centromère. Les chromosomes vont par paire, l'un provenant du père, l'autre de la mère. Le génome humain en compte 23 paires, soit 46 chromosomes au total.

© biology.unm.edu, CC by-nc-sa 3.0

ASTRONOMY - NGC 1360: The Robin's Egg Nebula

 2025 May 14

NGC 1360: The Robin's Egg Nebula
Image Credit & Copyright: Andrea Iorio, Vikas Chander & ShaRA Team

Explanation: This pretty nebula lies some 1,500 light-years away, its shape and color in this telescopic view reminiscent of a robin's egg. The cosmic cloud spans about 3 light-years, nestled securely within the boundaries of the southern constellation of the Furnace (Fornax). Recognized as a planetary nebula, egg-shaped NGC 1360 doesn't represent a beginning, though. Instead, it corresponds to a brief and final phase in the evolution of an aging star. In fact, visible at the center of the nebula, the central star of NGC 1360 is known to be a binary star system likely consisting of two evolved white dwarf stars, less massive but much hotter than the Sun. Their intense and otherwise invisible ultraviolet radiation has stripped away electrons from the atoms in their mutually surrounding gaseous shroud. The blue-green hue inside of NGC 1360 seen here is the strong emission produced as electrons recombine with doubly ionized oxygen atoms.