ASTRONOMY - The Long Tails Comet Tsuchinshan-ATLAS

 2024 October 7

The Long Tails Comet Tsuchinshan-ATLAS
Image Credit & Copyright: Jose Santivañez Mueras

Explanation: A bright comet is moving into the evening skies. C/2023 A3 (Tsuchinshan–ATLAS) has brightened and even though it is now easily visible to the unaided eye, it is so near to the Sun that it is still difficult to see. Pictured, Comet Tsuchinshan–ATLAS was captured just before sunrise from an Andes Mountain in Peru. Braving cold weather, this unusually high perch gave the astrophotographer such a low eastern horizon that the comet was obvious in the pre-dawn sky. Visible in the featured image is not only an impressively long dust tail extending over many degrees, but an impressively long and blue ion tail, too.  This month, as the comet moves out from the Sun and passes the Earth, evening observers should be able to see the huge dirty ice ball toward the west just after sunset.

ASTRONOMY - The Magnificent Tail of Comet McNaught

 2024 October 6

The Magnificent Tail of Comet McNaught
Image Credit & Copyright: Robert H. McNaught

Explanation: Comet McNaught, the Great Comet of 2007, grew a spectacularly long and filamentary tail. The magnificent tail spread across the sky and was visible for several days to Southern Hemisphere observers just after sunset. The amazing ion tail showed its greatest extent on long-duration, wide-angle camera exposures. During some times, just the tail itself was visible just above the horizon for many northern observers as well. Comet C/2006 P1 (McNaught), estimated to have attained a peak brightness of magnitude -5 (minus five), was caught by the comet's discoverer in the featured image just after sunset in January 2007 from Siding Spring Observatory in Australia. Comet McNaught, the brightest comet in decades, then faded as it moved further into southern skies and away from the Sun and Earth. Over the next month, Comet Tsuchinshan–ATLAS, a candidate for the Great Comet of 2024, should display its most spectacular tails visible from the Earth.

SANTé/MEDECINE - La grossesse mois par mois - 3ème mois

Les signes physiques de votre grossesse continuent sous l'effet des hormones, vous êtes enceinte de trois mois. Que se passe-t-il exactement ? Au cours de ce troisième mois de grossesse, les organes qui se sont formés commencent à fonctionner. La tête du futur bébé prend encore beaucoup de place. Découvrez tous ces changements en détail.

Apparence générale du fœtus

Les proportions de la tête par rapport au corps s'équilibrent, même si ce rapport est encore en faveur de la tête. C'est parce que le corps s'allonge. Au niveau de l'encéphale qui continue de grossir, la structure générale est présente. Deux renflements, un cervical et un lombaire, caractérisent la molle épinière. L'œil a maintenant sa rétine.

La peau du fœtus se compose de l'épiderme et du derme.

Le développement du fœtus plus en détail

Certains organes commencent à fonctionner. Ainsi le foie, très proéminent, produit de la bile. La moelle osseuse met en marche son usine pour produire des cellules sanguines.

L'ossification s'accélère tandis que les membres sont bien formés.

Le sexe du fœtus est visible grâce aux organes génitaux externes.

À la fin du troisième mois, le fœtus mesure environ 9 cm du vertex au coccyx.

FuturaSciences

ASTRONOMY - M27: Not a Comet

 2024 October 5

M27: Not a Comet
Image Credit & Copyright: Francesco Sferlazza, Franco Sgueglia

Explanation: While hunting for comets in the skies above 18th century France, astronomer Charles Messier diligently kept a list of the things encountered during his telescopic expeditions that were definitely not comets. This is number 27 on his now famous not-a-comet list. In fact, 21st century astronomers would identify it as a planetary nebula, but it's not a planet either, even though it may appear round and planet-like in a small telescope. Messier 27 (M27) is an excellent example of a gaseous emission nebula created as a sun-like star runs out of nuclear fuel in its core. The nebula forms as the star's outer layers are expelled into space, with a visible glow generated by atoms excited by the dying star's intense but invisible ultraviolet light. Known by the popular name of the Dumbbell Nebula, the beautifully symmetric interstellar gas cloud is over 2.5 light-years across and about 1,200 light-years away in the constellation Vulpecula. This impressive color image highlights details within the well-studied central region and fainter, seldom imaged features in the nebula's outer halo.

ASTRONOMY - Sardinia Sunset

 2025 September 6

Sardinia Sunset
Image Credit & Copyright: Lorenzo Busilacchi

Explanation: When the sun sets on September 7, the Full Moon will rise. And on that date denizens around much of our fair planet, including parts of Antarctica, Australia, Asia, Europe, and Africa can witness a total lunar eclipse, with the Moon completely immersed in Earth's shadow. As the bright Full Moon first enters Earth's shadow it will darken, finally taking on a reddish hue during the total eclipse phase. In fact, the color of the Moon during a total lunar eclipse is due to reddened light from sunrises and sunsets around planet Earth. The reddened sunlight is scattered by a dense atmosphere into the planet's otherwise dark central shadow. When the sun set on August 22, this telephoto snapshot of red skies, blue sea, and the Mangiabarche Lighthouse was captured from Sant'Antioco, Sardinia, Italy.

ASTRONOMIE - Iréelle

Cette vue d’artiste de la planète Cha 1107-7626 est publiée par l’Observatoire européen austral. Cette planète vagabonde est située à environ 620 années-lumière de la Terre et ne gravite autour d’aucune étoile. 

HANDOUT / AFP

ASTRONOMY - NGC 6960: The Witch's Broom Nebula

 2025 October 1

NGC 6960: The Witch's Broom Nebula
Image Credit & Copyright: Brian Meyers

Explanation: Ten thousand years ago, before the dawn of recorded human history, a new light would suddenly have appeared in the night sky and faded after a few weeks. Today we know this light was from a supernova, or exploding star, and record the expanding debris cloud as the Veil Nebula, a supernova remnant. This sharp telescopic view is centered on a western segment of the Veil Nebula cataloged as NGC 6960 but less formally known as the Witch's Broom Nebula. Blasted out in the cataclysmic explosion, an interstellar shock wave plows through space sweeping up and exciting interstellar material. Imaged with narrow band filters, the glowing filaments are like long ripples in a sheet seen almost edge on, remarkably well separated into atomic hydrogen (red) and oxygen (blue-green) gas. The complete supernova remnant lies about 1400 light-years away towards the constellation Cygnus. This Witch's Broom actually spans about 35 light-years. The bright star in the frame is 52 Cygni, visible with the unaided eye from a dark location but unrelated to the ancient supernova remnant.

SANTé/MEDECINE - La grossesse mois par mois - 2ème mois

L'embryon au cours du deuxième mois de grossesse

Le développement de l'embryon se fait rapidement. Ses bras et ses jambes se forment. Son visage se dessine. Les deux hémisphères cérébraux sont bien formés, ainsi que l'estomac, le pancréas et le foie. L'embryon découvre l'odorat.

À la sixième semaine de grossesse, le sexe est déterminé (bien qu'il ne soit pas encore visible). L'embryon mesure entre 10 et 14 millimètres, la différence avec le premier mois est bien visible ! Il grandira encore beaucoup jusqu'à atteindre 3 centimètres à la huitième semaine.

Vient ensuite la formation des yeux, des doigts et des orteils.

À la fin des huit premières semaines tous ses organes sont en place.

FuturaSciences

ASTRONOMY - Comet Lemmon Brightens

 2025 September 30

Comet Lemmon Brightens
Image Credit & Copyright: Victor Sabet & Julien De Winter

Explanation: Comet Lemmon is brightening and moving into morning northern skies. Besides Comet SWAN25B and Comet ATLAS, Comet C/2025 A6 (Lemmon) is now the third comet currently visible with binoculars and on long camera exposures. Comet Lemmon was discovered early this year and is still headed into the inner Solar System. The comet will round the Sun on November 8, but first it will pass its nearest to the Earth -- at about half the Earth-Sun distance -- on October 21. Although the brightnesses of comets are notoriously hard to predict, optimistic estimates have Comet Lemmon then becoming visible to the unaided eye. The comet should be best seen in predawn skies until mid-October, when it also becomes visible in evening skies. The featured image showing the comet's split and rapidly changing ion tail was taken in Texas, USA late last week.

ASTRONOMY - Two Camera Comets in One Sky

2025 September 29

Two Camera Comets in One Sky
Image Credit & Copyright: Luc Perrot (TWAN)

Explanation: It may look like these comets are racing, but they are not. Comets C/2025 K1 ATLAS (left) and C/2025 R2 SWAN (right) appeared near each other by chance last week in the featured image taken from France's Reunion Island in the southern Indian Ocean. Fainter Comet ATLAS is approaching our Sun and will reach its closest approach in early October when it is also expected to be its brightest -- although still only likely visible with long exposures on a camera. The brighter comet, nicknamed SWAN25B, is now headed away from our Sun, although its closest approach to Earth is expected in mid-October, when optimistic estimates have it becoming bright enough to see with the unaided eye. Each comet has a greenish coma of expelled gas and an ion tail pointing away from the Sun.