Nereide

26 Oct. 1868: at the session of the Académie des Sciences in Paris, two independent reports are read — one from Pierre J. C. Janssen and one from J. N. Lockyer. Both describe a spectroscopic method for observing solar prominences in broad daylight, without waiting for an eclipse. 🔭🧪⚛️ #histsci

In short: - observations of the yellow line → 18 Aug (Janssen) and 20 Oct (Lockyer) 1868 - official reading of the method → 26 Oct 1868 - recognition as a new element → later A clear case of independent discovery of the same method, and the start of the helium story.

archive.orgComptes Rendus Hebdomadaires des Séances de l'Académie des Sciences 1868-10-26: Vol 67 Iss 17

In the first post: animation of a standard helium atom (2 green protons, 2 white neutrons, 2 blue electrons). Credit: NASA/Dana Berry Primary source (Comptes Rendus, séance du 26 octobre 1868): archive.org/details/comp... AAS article: aas.org/posts/news/2...

The yellow line was noted, but neither report yet presented it as clear evidence of a new element. The Academy later awarded a medal to both for the method of observing solar prominences.

In the following weeks, Lockyer (working with Edward Frankland) became convinced the yellow line (later called D₃) belonged to an element unknown on Earth. He named it helium (from the Greek helios = Sun). The element was isolated on Earth only in 1895 by William Ramsay.

The actual observations had taken place earlier. 18 Aug. 1868: while watching the total solar eclipse in India, Janssen looks at the spectrum of the prominences and spots a bright yellow line that doesn’t match sodium.

20 Oct. 1868: Lockyer, in England, independently observes the same prominences in daylight and sees the identical line. In the reports read on 26 October, the main result highlighted was the new method itself.

Nereide reposted

A study by Greer et al. (Geochemical Perspectives Letters, 23 Oct 2023) claims our #Moon is about 40 million years older than thought, by analyzing lunar crystals gathered by the Apollo 17 crew in 1972. geochemicalperspectivesletters.org/article2334/ 🔭🧪⚛️

Nereide reposted

Fascinating thread on the #geology and the current look of eastern #Washington. Beneath that basalt lava and those thin soils there’s also the history of the Whitman Mission and the Nez Perce.🧪 The "sick" land Emily Lakdawalla describes has more layers than you see at first glance.

Emily Lakdawalla 🏳️‍⚧️ Uranus Expert@elakdawalla.bsky.social

Today I flew into Spokane, WA and drove 3 hours to stay with my aunt in Walla Walla. This is the east end of Washington state, a route I haven’t driven before. It’s all basalt lava with a thin veneer of weathered soil. It’s a weird landscape, geologically.

Nereide reposted

lkb.frClaude Cohen-Tannoudji has passed away - Laboratoire Kastler Brossel

Cohen-Tannoudji was a founding figure of quantum optics & cold-atom physics, always combining theory & experiment, and an exceptional teacher. Nobel lecture quoted E. Rostand: "It's at night that it's beautiful to believe in the light", reflecting his humanism. 🧪⚛️🔭 RIP www.lkb.fr/en/laboratoi...

Emily Lakdawalla 🏳️‍⚧️ Uranus Expert@elakdawalla.bsky.social

Nereide reposted

15 Nov 2025

🧵 This intriguing picture by Stephen Kennedy shows a vast nebula complex recalling a shark, and so commonly referred to as the Shark Nebula. ➡️ apod.nasa.gov/apod/ap23061... It includes smaller dust nebulae such as LDN (Lynds Dark Nebula) 1235 and Van den Bergh 149 & 150. 🔭 🧪 #science 1/5

Nereide reposted

16 Jan

🧵 Check out this stunning "Lunar Curve" (not a lunar analemma), by Giorgia Hofer! 🔭 It looks magical, with the #Moon tracing a path 🧪 over the mountains. Actually, it's a beautiful digital composite montage, not something you can actually see in real life. #sciart 1/5

Nereide reposted

Astronomer Ptolemy called it "a nebula following the sting of Scorpius" in 130 AD. Messier catalogued it in 1764. But Giovanni Battista Hodierna had already seen it before 1654 (counting 30 stars) and Lacaille described it as a square of 15–20 stars in 1752. 🔭🧪⚛️ #astronomy

ESO@eso.org

Diamonds in the tail of the scorpion 💎 🦂 Easily spotted with the naked eye close to the tail of the constellation of Scorpius, Messier 7 is one of the most prominent open clusters of stars in the sky — making it an important astronomical research target. https://www.eso.org/public/news/eso1406/ 🔭

lkb.frClaude Cohen-Tannoudji has passed away - Laboratoire Kastler Brossel

Nereide reposted

This beautiful Hubble image features, in spectacular detail, NGC 6217, a barred spiral galaxy located some 60 million light years away in Ursa Minor. apod.nasa.gov/apod/ap22022... Image Credit: NASA / ESA / and the Hubble SM4 ERO Team 🔭🧪⚛️ #cosmology

Nereide reposted

13 Apr

1/2 Long before they had telescopes, humans kept an eye on the Sun. 1375 BCE: Babylonians used stone tablets to record solar eclipses. Image: Babylonian Tablet listing eclipses between 518 and 465 BCE, mentioning the death of king Xerxes Licence: CC0 1.0 Universal 🔭🧪⚛️ #histsci

ESO@eso.org

Today, with southern-hemisphere telescopes, we can study it properly: it also contains magnetic chemically peculiar stars. And it doesn’t end there. In 2006 Messier 7 was used for the first official image of LORRI camera on New Horizons, on its way to Pluto.🔭

A cluster known for nearly two thousand years that ended up as a "test" for a space mission. The ESO press release gives the scientific context that explains why it's still worth observing so carefully.🔭

ESO@eso.org

@johncarlosbaez.bsky.social

So how can such a bright and ancient object still be so interesting to astronomers? One reason is that Messier 7 is the southernmost object in the entire Messier catalogue. For centuries it was hard to observe from Europe, so many "rediscovered" it on their own. 🔭

Nereide reposted

John C. Baez

Check out my talk tomorrow! I'm talking 13:00 to 14:00 UK time at the Higgs Centre Seminar Room at the University of Edinburgh, but you can also join online: teams.microsoft.com/meet/3495593... (passcode: ZE3w4xn2) and you can also see my slides: math.ucr.edu/home/baez/pa...

Nereide reposted

The phenomenon of the horns extending beyond 180° was already noted by Johann Schröter in the late 18th century and was one of the first independent pieces of evidence for the existence of a dense atmosphere around Venus. Striking images like this one make it particularly clear. 🔭🧪⚛️ #sciart

This post is unavailable.

Nereide reposted

The Great Carina Nebula, also known as NGC 3372, is one of the largest H II regions in the heart of Southern Milky Way, in the Carina constellation. Visible to the unaided eye under the right conditions, it is at a distance of ~ 7,500 ly. science.nasa.gov/image-articl... 🔭🧪⚛️ #galactic

Nereide reposted

At the South Pole a research team from 30 institutions has recently put together one of the sharpest maps of how matter is distributed in the universe. Photo by Daniel Michalik Press release: news.uchicago.edu/story/south-... 🔭🧪⚛️ #cosmology

A supermassive black hole (SMBH) probably harbors in the AGN. Scientists believe that the barred spirals allow gas to be channeled from the disk towards the nucleus, triggering episodes of star formation and fueling the central SMBH.

iopscience.iop.orgSN 2018gj: A Short Plateau Type II Supernova with Persistent Blueshifted Ha EmissionSN 2018gj: A Short Plateau Type II Supernova with Persistent Blueshifted Ha Emission, Teja, Rishabh Singh, Singh, Avinash, Sahu, D. K., Anupama, G. C., Kumar, Brajesh, Nakaoka, Tatsuya, Kawabata, Koji S, Yamanaka, Masayuki, Takey, Ali, Kawabata, Miho

SN 2018gj is a Type IIP supernova that occurred on the outskirts of NGC 6217. Relative to ordinary galaxies, NGC 6217 is forming stars at a high pace and is therefore labeled a starburst. Paper: iopscience.iop.org/article/10.3...

Its evident feature is a prominent bar of stars across the center. Numerous pinkish regions, visible in the galaxy, are made up of hydrogen done bright by nearby massive stars.

At the core of NGC 6217, spanning some 30,000 light years across, there is a low-luminosity active galactic nucleus (AGN) that has formed an H II region, an emission nebula associated with young, blue, hot stars.

This post is unavailable.

Under ideal conditions, very close to inferior conjunction, the 2 horns can join together and form an almost complete atmospheric ring of light around the disk (the so-called atmospheric ring of Venus). It is a rare phenomenon and very difficult to capture due to the planet’s proximity to the Sun.

NGC 3372 spans over 300 ly, surrounds several open clusters, and one of the most massive stars known: the variable η Carinae. According to the most accredited theories, this star is expected to end as a great supernova in the near future.