ASTRONOMY - Gigantic Jet Lightning from Puerto Rico

 2021 September 29

Gigantic Jet Lightning from Puerto Rico
Video Credit & Copyright: Frankie Lucena

Explanation: Have you ever seen a gigantic jet? They are extremely rare but tremendously powerful. Gigantic jets are a type of lightning discharge documented only this century that occur between some thunderstorms and the Earth's ionosphere high above them. Pictured above is the middle and top of one such jet caught last week by a lightning and meteor camera from Puerto Rico, USA. The jet traversed perhaps 70 kilometers in just under one second. Gigantic jets are much different from regular cloud-to-cloud and cloud-to-ground lightning. The bottoms of gigantic jets appear similar in appearance to another type cloud-to-above strike called blue jets, while the tops appear similar to upper-atmosphere red sprites. Although the mechanism and trigger that causes gigantic jets is a topic of research, it is clear that the jets reduce charge imbalance between different parts of Earth's atmosphere. A good way to look for gigantic jets is to watch a powerful but distant thunderstorm from a clear location.

ASTRONOMY - Unwrapped: Five Decade Old Lunar Selfie

 2021 September 27

Unwrapped: Five Decade Old Lunar Selfie
Image Credit: NASA, Apollo 11, Neil Armstrong; Processing: Michael Ranger

Explanation: Here is one of the most famous pictures from the Moon -- but digitally reversed. Apollo 11 landed on the moon in 1969 and soon thereafter many pictures were taken, including an iconic picture of Buzz Aldrin taken by Neil Armstrong. The original image captured not only the magnificent desolation of an unfamiliar world, but Armstrong himself reflected in Aldrin's curved visor. Enter modern digital technology. In the featured image, the spherical distortion from Aldrin's helmet has been reversed. The result is the famous picture -- but now featuring Armstrong himself from Aldrin's perspective. Even so, since Armstrong took the picture, the image is effectively a five-decade old lunar selfie. The original visor reflection is shown on the left, while Earth hangs in the lunar sky on the upper right. A foil-wrapped leg of the Eagle lander is prominently visible. Preparations to return humans to the Moon in the next few years include the Artemis program, an international collaboration led by NASA.

ASTRONOMY - Harvest Moon Trail

 2021 September 23

Harvest Moon Trail
Image Credit & Copyright: Mike Cohea

Explanation: Famed in festival, story, and song the best known full moon is the Harvest Moon. For northern hemisphere dwellers that's a traditional name of the full moon nearest the September equinox. Seen from Saunderstown, Rhode Island, planet Earth, this Harvest Moon left a broad streak of warm hues as it rose through a twilight sky over the Newport Bridge. On September 20 its trail was captured in a single 22 minute exposure using a dense filter and a digital camera. Only two days later the September equinox marked a change of season and the beginning of autumn in the north. In fact, recognizing a season as the time between solstice and equinox, this Harvest Moon was the fourth full moon of the season, coming just before the astronomical end of northern summer.

ASTRONOMY - Equinox on a Spinning Earth

 2021 September 22

Equinox on a Spinning Earth
Image Credit: Meteosat 9, NASA, earthobservatory, Robert Simmon

Explanation: When does the line between night and day become vertical? Today. Today is an equinox on planet Earth, a time of year when day and night are most nearly equal. At an equinox, the Earth's terminator -- the dividing line between day and night -- becomes vertical and connects the north and south poles. The featured time-lapse video demonstrates this by displaying an entire year on planet Earth in twelve seconds. From geosynchronous orbit, the Meteosat 9 satellite recorded these infrared images of the Earth every day at the same local time. The video started at the September 2010 equinox with the terminator line being vertical. As the Earth revolved around the Sun, the terminator was seen to tilt in a way that provides less daily sunlight to the northern hemisphere, causing winter in the north. As the year progressed, the March 2011 equinox arrived halfway through the video, followed by the terminator tilting the other way, causing winter in the southern hemisphere -- and summer in the north. The captured year ends again with the September equinox, concluding another of billions of trips the Earth has taken -- and will take -- around the Sun.

INFORMATIQUE - Contrôle routier

A partir du 1er novembre 2021, les applis de guidage par GPS et d'aide à la conduite seront tenues, dans certaines circonstances, de ne plus signaler la présence des forces de l'ordre à leurs utilisateurs.

44%. C'est, selon le ministère de l'Intérieur, le pourcentage de décès liés à l'alcool ou à l'utilisation de stupéfiants dans les accidents de la route. Pour tenter de lutter contre ce fléau, mais aussi dans des situations particulières comme des alertes enlèvement ou des attaques terroristes, l'Etat pourra, à compter du 1er novembre prochain, exiger des applications collaboratives de navigation GPS (telles que Waze, Coyote, TomTom, Garmin, Michelin TravelPartner ou Glob) de cacher, c'est-à-dire de ne plus signaler à leurs utilisateurs, la présence de forces de l'ordre ou de contrôles de police dans un périmètre donné et pour un temps limité. L'objectif étant de faire jouer l'effet de surprise afin que les personnes visées (parfois utilisatrices d'applications GPS) ne puissent précisément pas se soustraire à d'éventuels contrôles mis en place par les forces de l'ordre. En pratique, selon le décret 2021-468 publié au Journal officiel du 20 avril 2021 et qui vient compléter l'article L130-11 du Code de la route, cette demande d'interdiction de signalement prendra la forme d'un arrêté. Elle ne pourra émaner que de deux autorités publiques : le ministère de l'Intérieur et le préfet "sur proposition des officiers ou agents de police judiciaire et des agents de police judiciaire adjoints de la gendarmerie et de la police nationales"

Ces dispositions exceptionnelles s'appliqueront, selon les cas, pour une durée pouvant aller de 2 heures (pour les contrôles d'alcoolémie et de stupéfiants) à 12 heures (s'agissant de recherches d'individus en lien avec une "alerte enlèvement" ou une attaque terroriste). De même, ces mesures seront circonscrites et ne pourront pas concerner, même temporairement, l'ensemble du territoire. "Les voies ou portions de voies concernées ne peuvent s'étendre au-delà d'un rayon de dix kilomètres autour du point de contrôle routier lorsque celui-ci est situé hors agglomération et au-delà de deux kilomètres autour du point de contrôle routier lorsque celui-ci est situé en agglomération", précise l'article L130-11 du Code de la route. 

En cas de non-respect des interdictions décidées soit par le préfet, soit par le ministère de l'Intérieur, les responsables d'applications GPS seront passibles de 2 ans d'emprisonnement et de 30 000 euros d'amende. A noter cependant, les usagers de services comme Waze, Coyote, TomTom ou Garmin ne risqueront rien et pourront continuer à signaler la présence des forces de l'ordre. Mais, au final, l'information ne sera pas transmise à la communauté des utilisateurs, comme c'est le cas en temps normal. Les applications GPS permettent le plus souvent de fluidifier la circulation. Cependant, avec la mise en place de ces interdictions de signalement, elles pourraient perdre de leur attrait aux yeux d'utilisateurs qui aiment parfois flirter avec la ligne rouge, c'est-à-dire conduire è haute vitesse, sous l'emprise de stupéfiants et/ou se soustraire à des contrôles de police. Opposé à ce nouveau cadre juridique et anticipant très certainement des retombées négatives sur son activité, l'application GPS Coyote a récemment, comme le révélait le site NextInpact, introduit une requête auprès du Conseil d'Etat pour demander l'annulation du décret publié au printemps dernier.

ASTRONOMY - Lynds Dark Nebula 1251

 2021 September 20

Lynds Dark Nebula 1251
Image Credit & Copyright: Cristiano Gualco

Explanation: Stars are forming in Lynds Dark Nebula (LDN) 1251. About 1,000 light-years away and drifting above the plane of our Milky Way galaxy, the dusty molecular cloud is part of a complex of dark nebulae mapped toward the Cepheus flare region. Across the spectrum, astronomical explorations of the obscuring interstellar clouds reveal energetic shocks and outflows associated with newborn stars, including the telltale reddish glow from scattered Herbig-Haro objects hiding in the image. Distant background galaxies also lurk on the scene, almost buried behind the dusty expanse. This alluring view spans over two full moons on the sky, or 17 light-years at the estimated distance of LDN 1251.

ASTRONOMY - Rings and Seasons of Saturn

 021 September 19

Rings and Seasons of Saturn
Image Credit & Copyright: Damian Peach/SEN

Explanation: On Saturn, the rings tell you the season. On Earth, Wednesday marks an equinox, the time when the Earth's equator tilts directly toward the Sun. Since Saturn's grand rings orbit along the planet's equator, these rings appear most prominent -- from the direction of the Sun -- when the spin axis of Saturn points toward the Sun. Conversely, when Saturn's spin axis points to the side, an equinox occurs and the edge-on rings are hard to see from not only the Sun -- but Earth. In the featured montage, images of Saturn between the years of 2004 and 2015 have been superposed to show the giant planet passing from southern summer toward northern summer. Saturn was as close as it can get to planet Earth last month, and this month the ringed giant is still bright and visible throughout much of the night

AERONAUTIQUE - La reaversée de la Manche en flyboard

 

ASTRONOMY - Video: Flash on Jupiter

 2021 September 17

Video: Flash on Jupiter
Video Credit & Copyright: T. Humbert, S. Barré, A. Desmougin & D. Walliang (Société Lorraine d'Astronomie), Astroqueyras

Explanation: There has been a flash on Jupiter. A few days ago, several groups monitoring our Solar System's largest planet noticed a two-second long burst of light. Such flashes have been seen before, with the most famous being a series of impactor strikes in 1994. Then, fragments of Comet Shoemaker-Levy 9 struck Jupiter leaving dark patches that lasted for months. Since then, at least seven impacts have been recorded on Jupiter -- usually discovered by amateur astronomers. In the featured video, variations in the Earth's atmosphere cause Jupiter's image to shimmer when, suddenly, a bright flash appears just left of center. Io and its shadow are visible on the right. What hit Jupiter will likely never be known, but considering what we do know of the nearby Solar System, it was likely a piece of rocky and ice -- perhaps the size of a bus -- that broke off long-ago from a passing comet or asteroid.

ASTRONOMY - Firefly Milky Way over Russia

 2021 September 6

Firefly Milky Way over Russia
Image Credit & Copyright: Anton Komlev

Explanation: It started with a pine tree. The idea was to photograph a statuesque pine in front of the central band of our Milky Way Galaxy. And the plan, carried out two months ago, was successful -- they both appear prominently. But the resulting 3-frame panorama captured much more. Colorful stars, for example, dot the distant background, with bright Altair visible on the upper left. The planet Saturn, a bit closer, was captured just over the horizon on the far left. Just beyond the Earth's atmosphere, seen in the upper right, an Earth-orbiting satellite was caught leaving a streak during the 25-second exposure. The Earth's atmosphere itself was surprisingly visible -- as green airglow across the image top. Finally, just by chance, there was a firefly. Do you see it? Near the image bottom, the firefly blinked in yellow several times as it fluttered before the rolling hills above Milogradovka River in Primorsky Krai, Russia.