ASTRONOMY - Ou4: The Giant Squid Nebula

 2022 October 12

Ou4: The Giant Squid Nebula
Image Credit & Copyright: Tommy Lease

Explanation: A mysterious squid-like cosmic cloud, this nebula is very faint, but also very large in planet Earth's sky. In the image, composed with 30 hours of narrowband image data, it spans nearly three full moons toward the royal constellation Cepheus. Discovered in 2011 by French astro-imager Nicolas Outters, the Squid Nebula's bipolar shape is distinguished here by the telltale blue-green emission from doubly ionized oxygen atoms. Though apparently surrounded by the reddish hydrogen emission region Sh2-129, the true distance and nature of the Squid Nebula have been difficult to determine. Still, a more recent investigation suggests Ou4 really does lie within Sh2-129 some 2,300 light-years away. Consistent with that scenario, the cosmic squid would represent a spectacular outflow of material driven by a triple system of hot, massive stars, cataloged as HR8119, seen near the center of the nebula. If so, this truly giant squid nebula would physically be over 50 light-years across.

ASTRONOMY - Stars, Dust, Pillars, and Jets in the Pelican Nebula

 2022 October 11

Stars, Dust, Pillars, and Jets in the Pelican Nebula
Image Credit & Copyright: Adriano Almeida

Explanation: What dark structures arise within the Pelican Nebula? On the whole, the nebula appears like a bird (a pelican) and is seen toward the constellation of a different bird: Cygnus, a Swan. But inside, the Pelican Nebula is a place lit up by new stars and befouled by dark dust. Smoke-sized dust grains start as simple carbon compounds formed in the cool atmospheres of young stars but are dispersed by stellar winds and explosions. Two impressive Herbig-Haro jets are seen emitted by the star HH 555 on the right, and these jets are helping to destroy the light year-long dust pillar that contains it. Other pillars and jets are also visible. The featured image was scientifically-colored to emphasize light emitted by small amounts of heavy elements in a nebula made predominantly of the light elements hydrogen and helium. The Pelican Nebula (IC 5067 and IC 5070) is about 2,000 light-years away and can be found with a small telescope to the northeast of the bright star Deneb.

ASTRONOMY - A Double Lunar Analemma over Turkey

 2022 October 10

A Double Lunar Analemma over Turkey
Image Credit & Copyright: Betul Turksoy

Explanation: An analemma is that figure-8 curve you get when you mark the position of the Sun at the same time each day for one year. But the trick to imaging an analemma of the Moon is to wait bit longer. On average the Moon returns to the same position in the sky about 50 minutes and 29 seconds later each day. So photograph the Moon 50 minutes 29 seconds later on successive days. Over one lunation or lunar month it will trace out an analemma-like curve as the Moon's actual position wanders due to its tilted and elliptical orbit. Since the featured image was taken over two months, it actually shows a double lunar analemma. Crescent lunar phases too thin and faint to capture around the New moon are missing. The two months the persistent astrophotographer chose were during a good stretch of weather during July and August, and the location was Kayseri, Turkey

MUSIC - Maciej Tomasiewicz - Johannes Brahms - Hungarian Dances No. 5 & 6

"Hungarian Dances No. 5 & 6"

MACROPHOTOGRAPHIE - Miki Asai - Après le déluge une fourmi…

 

Une petite averse qui tombe sur votre jardin par un doux matin de printemps et c'est tout un monde qui est bouleversé. Pour la fourmi, la flaque qui mouille à peine vos chaussures représente tout un océan d'eau. Une question d'échelle. Et la Japonaise Miki Asai, passionnée de macrophotographie, l'a bien compris. Ce qui se passe à l'abri de nos regards est fascinant.

Alors selon vous, cette fourmi aventureuse parviendra-t-elle à rejoindre l'autre rive de ce détroit formé par la pluie ? Un galet après l'autre, c'est ainsi que l'insecte semble condamné à envisager son avenir. 

© Miki Asai

FuturaSciences

ASTRONOMIE - Ce soir une belle étreinte entre la Lune et Jupiter

Positions respectives de la planète Jupiter et de la Lune le 8 octobre 2022 vers 20h (heure de Paris). Le cercle bleu représente un champ de 6 degrés typique d’une paire de jumelles 10×50.

Alors que la nuit s’installe au soir du 8 octobre 2022, tournez-vous vers l’est et regardez le duo formé par la Lune et par Jupiter s’élever progressivement au-dessus de l’horizon. Vers 20h, les deux astres sont éloignés de moins de trois degrés l’un de l’autre, une distance qui permet de les admirer ensemble dans une paire de jumelles. La Lune est quasiment pleine, mais l’intense lumière qu’elle diffuse n’est pas suffisante pour masquer Jupiter. En effet, la planète géante est étincelante en ce moment, tout simplement parce qu’elle se trouve presque au plus près de la Terre (son opposition a eu lieu le 26 septembre 2022).

Ce lumineux tandem planétaire s’admire tout au long de la nuit du 8 au 9 octobre. Au petit matin, la Lune qui se déplace bien plus vite que Jupiter sur le fond de ciel aura déjà pris un peu ses distances (à un peu plus de quatre degrés). Ce sera elle qui passera la dernière sous l’horizon, vers 7h.

Stelvision

ASTRONOMY - Two Comets in Southern Skies

 2022 October 8

Two Comets in Southern Skies
Image Credit & Copyright: Jose J. Chambo (Cometografia)

Explanation: Heading for its closest approach to the Sun or perihelion on December 20, comet C/2017 K2 (PanSTARRS) remains a sight for telescopic observers as it sweeps through planet Earth's southern hemisphere skies. First time visitor from the remote Oort cloud this comet PanSTARRS sports a greenish coma and whitish dust tail about half a degree long at the upper left in a deep image from September 21. It also shares the starry field of view toward the constellation Scorpius with another comet, 73P/Schwassmann-Wachmann 3, seen about 1 degree below and right of PanSTARRS. Astronomers estimate that first time visitor comet C/2017 K2 (PanSTARRS) has been inbound from the Oort cloud for some 3 million years along a hyperbolic orbit. Schwassmann-Wachmann 3 is more familiar though. The periodic comet loops through its own elliptical orbit, from just beyond the orbit of Jupiter to the vicinity of Earth's orbit, once every 5.4 years. Just passing in the night, this comet PanSTARRS is about 20 light-minutes from Earth in the September 21 image. Seen to be disintegrating since 1995, Schwassmann-Wachmann 3 was about 7.8 light-minutes away.

ASTRONOMY - In Ganymede's Shadow

2022 October 7

In Ganymede's Shadow
Image Credit & Copyright: Andrew McCarthy

Explanation: At opposition, opposite the Sun in Earth's sky, late last month Jupiter is also approaching perihelion, the closest point to the Sun in its elliptical orbit, early next year. That makes Jupiter exceptionally close to our fair planet, currently resulting in excellent views of the Solar System's ruling gas giant. On September 27, this sharp image of Jupiter was recorded with a small telescope from a backyard in Florence, Arizona. The stacked video frames reveal the massive world bounded by planet girdling winds. Dark belts and light zones span the gas giant, along with rotating oval storms and its signature Great Red Spot. Galilean moon Ganymede is below and right in the frame. The Solar System's largest moon and its shadow are in transit across the southern Jovian cloud tops.

ASTRONOMY - NGC 4631: The Whale Galaxy

 2022 October 6

NGC 4631: The Whale Galaxy
Image Credit & Copyright: Michael Sherick

Explanation: NGC 4631 is a big beautiful spiral galaxy. Seen edge-on, it lies only 25 million light-years away in the well-trained northern constellation Canes Venatici. The galaxy's slightly distorted wedge shape suggests to some a cosmic herring and to others its popular moniker, The Whale Galaxy. Either way, it is similar in size to our own Milky Way. In this sharp color image, the galaxy's yellowish core, dark dust clouds, bright blue star clusters, and red star forming regions are easy to spot. A companion galaxy, the small elliptical NGC 4627 is just above the Whale Galaxy. Faint star streams seen in deep images are the remnants of small companion galaxies disrupted by repeated encounters with the Whale in the distant past. The Whale Galaxy is also known to have spouted a halo of hot gas glowing in X-rays.

ASTRONOMY - Expanding Plume from DART's Impact

2022 October 5

Expanding Plume from DART's Impact
Video Credit: Les Makes Observatory, J. Berthier, F. Vachier, A. Klotz, P. Thierry, T. Santana-Ros, ESA NEOCC, D. Föhring, E. Petrescu, M. Micheli

Explanation: What happens if you crash a spaceship into an asteroid? In the case of NASA's DART spaceship and the small asteroid Dimorphos, as happened last week, you get quite a plume. The goal of the planned impact was planetary protection -- to show that the path of an asteroid can be slightly altered, so that, if done right, a big space rock will miss the Earth. The high brightness of the plume, though, was unexpected by many, and what it means remains a topic of research. One possibility is that 170-meter wide Dimorphos is primarily a rubble pile asteroid and the collision dispersed some of the rubble in the pile. The featured time-lapse video covers about 20 minutes and was taken from the Les Makes Observatory on France's Reunion Island, off the southeast coast of southern Africa. One of many Earth-based observatories following the impact, the initial dot is primarily Dimorphos's larger companion: asteroid Didymos. Most recently, images show that the Didymos - Dimorphos system has developed comet-like tails.