David ALBERTO
@astrolabe-science.fr
French Physics & Chem. teacher. He. Astronomy, sundials.
Prof. phys.-chim. lycée tech.
Astronomie, gnomonique, instruments astro. anciens. Also on Mastodon
💻Python, TeXLaTeX
🗣️ 🇫🇷 🇬🇧 🇪🇸 🇵🇹
Assos : UdPPC, SAF, CLEA.
www.astrolabe-science.fr
Prof. phys.-chim. lycée tech.
Astronomie, gnomonique, instruments astro. anciens. Also on Mastodon
💻Python, TeXLaTeX
🗣️ 🇫🇷 🇬🇧 🇪🇸 🇵🇹
Assos : UdPPC, SAF, CLEA.
www.astrolabe-science.fr
I finally managed to make a decent vertical version of my plane refraction #sundial, with a tailor-made stand for the plexiglas cylinder. Hour is read on the north side, by the position of the shadow.
Had to sand the cylinder all around to avoid internal reflections (caustics).
🔭 🧪 #EduSky
Had to sand the cylinder all around to avoid internal reflections (caustics).
🔭 🧪 #EduSky
November 8, 2025 at 1:26 PM
Le portail comporte des chouettes sculptées.
J’ai pris les photos aussi pour le tulipier de Virginie, l’un de mes arbres préférés.🍁🌳
J’ai pris les photos aussi pour le tulipier de Virginie, l’un de mes arbres préférés.🍁🌳
November 4, 2025 at 4:23 PM
Le portail comporte des chouettes sculptées.
J’ai pris les photos aussi pour le tulipier de Virginie, l’un de mes arbres préférés.🍁🌳
J’ai pris les photos aussi pour le tulipier de Virginie, l’un de mes arbres préférés.🍁🌳
Le lycée international des Pontonniers, à Strasbourg.
Achevé en 1902, quand la ville était allemande.
Lycée public avec plusieurs sections internationales. Pratique, dans une ville où vivent beaucoup d’employés des institutions européennes.
Achevé en 1902, quand la ville était allemande.
Lycée public avec plusieurs sections internationales. Pratique, dans une ville où vivent beaucoup d’employés des institutions européennes.
November 4, 2025 at 4:23 PM
Le lycée international des Pontonniers, à Strasbourg.
Achevé en 1902, quand la ville était allemande.
Lycée public avec plusieurs sections internationales. Pratique, dans une ville où vivent beaucoup d’employés des institutions européennes.
Achevé en 1902, quand la ville était allemande.
Lycée public avec plusieurs sections internationales. Pratique, dans une ville où vivent beaucoup d’employés des institutions européennes.
Good question. I guess it depends on epochs, cultures, makers…
Look, this old one prefers IIII instead of IV.
Look, this old one prefers IIII instead of IV.
November 3, 2025 at 2:13 PM
Good question. I guess it depends on epochs, cultures, makers…
Look, this old one prefers IIII instead of IV.
Look, this old one prefers IIII instead of IV.
🔭🧪
For #sundialSunday
A painted vertical #sundial in Strasbourg, France. Rue des dentelles.
Recently restored, unfortunately the gnomon is bent.
For #sundialSunday
A painted vertical #sundial in Strasbourg, France. Rue des dentelles.
Recently restored, unfortunately the gnomon is bent.
November 2, 2025 at 9:14 PM
🔭🧪
For #sundialSunday
A painted vertical #sundial in Strasbourg, France. Rue des dentelles.
Recently restored, unfortunately the gnomon is bent.
For #sundialSunday
A painted vertical #sundial in Strasbourg, France. Rue des dentelles.
Recently restored, unfortunately the gnomon is bent.
Left : the « astrologer sundial ».
A classical vertical sundial. This one is barely readable because it’s set quite high and its lines are worn.
Right : the « youth with a sundial ». In fact a « mass dial » marking the times of prayers.
3/3
A classical vertical sundial. This one is barely readable because it’s set quite high and its lines are worn.
Right : the « youth with a sundial ». In fact a « mass dial » marking the times of prayers.
3/3
October 31, 2025 at 8:38 PM
Left : the « astrologer sundial ».
A classical vertical sundial. This one is barely readable because it’s set quite high and its lines are worn.
Right : the « youth with a sundial ». In fact a « mass dial » marking the times of prayers.
3/3
A classical vertical sundial. This one is barely readable because it’s set quite high and its lines are worn.
Right : the « youth with a sundial ». In fact a « mass dial » marking the times of prayers.
3/3
On the left : a sundial marking altitude (curved lines) and azimut (straight lines) of the Sun.
On the right : a sundial with italic hours (hours since sunset) and babylonic hours (hours since sunrise).
2/3
On the right : a sundial with italic hours (hours since sunset) and babylonic hours (hours since sunrise).
2/3
October 31, 2025 at 8:38 PM
On the left : a sundial marking altitude (curved lines) and azimut (straight lines) of the Sun.
On the right : a sundial with italic hours (hours since sunset) and babylonic hours (hours since sunrise).
2/3
On the right : a sundial with italic hours (hours since sunset) and babylonic hours (hours since sunrise).
2/3
🔭🧪 #sundial
So delighted to be back in Strasbourg (France), even only for a week.
The cathedral hosts no less than 5 sundials on its southern side, the first three being called « Dasypodius » sundials. Dated 1572 and 1609.
1/3
So delighted to be back in Strasbourg (France), even only for a week.
The cathedral hosts no less than 5 sundials on its southern side, the first three being called « Dasypodius » sundials. Dated 1572 and 1609.
1/3
October 31, 2025 at 8:38 PM
🔭🧪 #sundial
So delighted to be back in Strasbourg (France), even only for a week.
The cathedral hosts no less than 5 sundials on its southern side, the first three being called « Dasypodius » sundials. Dated 1572 and 1609.
1/3
So delighted to be back in Strasbourg (France), even only for a week.
The cathedral hosts no less than 5 sundials on its southern side, the first three being called « Dasypodius » sundials. Dated 1572 and 1609.
1/3
Et au passage, ça fait plaisir de reconnaître le petit cadran solaire du @cleaastro.bsky.social sur la table !🥰
October 25, 2025 at 2:15 PM
Et au passage, ça fait plaisir de reconnaître le petit cadran solaire du @cleaastro.bsky.social sur la table !🥰
Oui, je ne sais pas ce qui s’est passé… c’est juste le compas fermé.
October 24, 2025 at 12:16 PM
Oui, je ne sais pas ce qui s’est passé… c’est juste le compas fermé.
My 1st attempt at a proportional compass (laser cut). Needs a few tweaks but OK. (Scales barely readable).
This is a great mathematical instrument from the 17th-18th c. designed for various calculations, especially useful to draw plans.
poke @olonguet.bsky.social
#ITeachMath #MathSky #lasercut
This is a great mathematical instrument from the 17th-18th c. designed for various calculations, especially useful to draw plans.
poke @olonguet.bsky.social
#ITeachMath #MathSky #lasercut
October 23, 2025 at 5:53 PM
My 1st attempt at a proportional compass (laser cut). Needs a few tweaks but OK. (Scales barely readable).
This is a great mathematical instrument from the 17th-18th c. designed for various calculations, especially useful to draw plans.
poke @olonguet.bsky.social
#ITeachMath #MathSky #lasercut
This is a great mathematical instrument from the 17th-18th c. designed for various calculations, especially useful to draw plans.
poke @olonguet.bsky.social
#ITeachMath #MathSky #lasercut
Make your own conical sundial and pretend it's the same as this exquisite 16thc. brass sundial.
2nd photo from a book by sundial maker Georg Brentel (1608).
5/5
2nd photo from a book by sundial maker Georg Brentel (1608).
5/5
October 21, 2025 at 6:38 PM
Make your own conical sundial and pretend it's the same as this exquisite 16thc. brass sundial.
2nd photo from a book by sundial maker Georg Brentel (1608).
5/5
2nd photo from a book by sundial maker Georg Brentel (1608).
5/5
3/☀️
Settings for other places : North America, India.
Sorry Southerners, this script is designed for the northern hemisphere, and would have to be re-written for the south.
Settings for other places : North America, India.
Sorry Southerners, this script is designed for the northern hemisphere, and would have to be re-written for the south.
October 21, 2025 at 6:38 PM
3/☀️
Settings for other places : North America, India.
Sorry Southerners, this script is designed for the northern hemisphere, and would have to be re-written for the south.
Settings for other places : North America, India.
Sorry Southerners, this script is designed for the northern hemisphere, and would have to be re-written for the south.
2/☀️
The diurnal arcs crossing the hour lines are followed by the shadow on the 21st of each month (approx). These lines also tell the sunrise/sunset times where they join the cone's rim.
The printed document:
The diurnal arcs crossing the hour lines are followed by the shadow on the 21st of each month (approx). These lines also tell the sunrise/sunset times where they join the cone's rim.
The printed document:
October 21, 2025 at 6:38 PM
2/☀️
The diurnal arcs crossing the hour lines are followed by the shadow on the 21st of each month (approx). These lines also tell the sunrise/sunset times where they join the cone's rim.
The printed document:
The diurnal arcs crossing the hour lines are followed by the shadow on the 21st of each month (approx). These lines also tell the sunrise/sunset times where they join the cone's rim.
The printed document:
🇬🇧 Making your customized DIY cell model at the Science fair. Big success at our booth!
🇫🇷 Fabriquer sa maquette de cellule personnalisée, à la fête de la science. Un gros succès sur notre stand !
#biology 🧪
🇫🇷 Fabriquer sa maquette de cellule personnalisée, à la fête de la science. Un gros succès sur notre stand !
#biology 🧪
October 11, 2025 at 12:42 PM
🇬🇧 Making your customized DIY cell model at the Science fair. Big success at our booth!
🇫🇷 Fabriquer sa maquette de cellule personnalisée, à la fête de la science. Un gros succès sur notre stand !
#biology 🧪
🇫🇷 Fabriquer sa maquette de cellule personnalisée, à la fête de la science. Un gros succès sur notre stand !
#biology 🧪
Même impression ici.
Et , au fait : #teamBac94
Et , au fait : #teamBac94
September 23, 2025 at 4:07 PM
Même impression ici.
Et , au fait : #teamBac94
Et , au fait : #teamBac94
🔭 🧪 #EduSky
Positions of planets around the Sun in the next 30 days (1 dot every 4 days). Earth: blue dots.
Saturn at opposition (today), Neptune in 2 days.
Mercury & Mars in the evening sky, getting close to each other as seen from 🌍
Venus still a morning planet.
A #Python script with Skyfield.
Positions of planets around the Sun in the next 30 days (1 dot every 4 days). Earth: blue dots.
Saturn at opposition (today), Neptune in 2 days.
Mercury & Mars in the evening sky, getting close to each other as seen from 🌍
Venus still a morning planet.
A #Python script with Skyfield.
September 21, 2025 at 7:36 PM
In 'Science In School' issue 74: a classroom activity exploring radioactivity with a Geiger-Muller detector. The radioactive source is potassium-40 in bags of potassium carbonate.
scienceinschool.org/issue/issue-...
Have you already tried that @peserlaterre.bsky.social ?
🎢 🧪
scienceinschool.org/issue/issue-...
Have you already tried that @peserlaterre.bsky.social ?
🎢 🧪
September 20, 2025 at 8:30 PM
In 'Science In School' issue 74: a classroom activity exploring radioactivity with a Geiger-Muller detector. The radioactive source is potassium-40 in bags of potassium carbonate.
scienceinschool.org/issue/issue-...
Have you already tried that @peserlaterre.bsky.social ?
🎢 🧪
scienceinschool.org/issue/issue-...
Have you already tried that @peserlaterre.bsky.social ?
🎢 🧪
🔭
Dans le magazine "L'Astronomie", n° 196 (septembre 2025), un article "Réalisation pratique d'un cadran solaire personnalisé", par F. Blateyron, auteur du logiciel Shadows. Ce logiciel propose une version gratuite :
www.shadowspro.com/index.html
Dans le magazine "L'Astronomie", n° 196 (septembre 2025), un article "Réalisation pratique d'un cadran solaire personnalisé", par F. Blateyron, auteur du logiciel Shadows. Ce logiciel propose une version gratuite :
www.shadowspro.com/index.html
September 18, 2025 at 11:16 AM
🔭
Dans le magazine "L'Astronomie", n° 196 (septembre 2025), un article "Réalisation pratique d'un cadran solaire personnalisé", par F. Blateyron, auteur du logiciel Shadows. Ce logiciel propose une version gratuite :
www.shadowspro.com/index.html
Dans le magazine "L'Astronomie", n° 196 (septembre 2025), un article "Réalisation pratique d'un cadran solaire personnalisé", par F. Blateyron, auteur du logiciel Shadows. Ce logiciel propose une version gratuite :
www.shadowspro.com/index.html
Did you know this old name for the Big Dipper? I didn't!
The calendar is a 4-loop spiral, the 1st being for a leap year, the 3 others for non-leap years.
'Equinoxial' is the celestial equator.
The hour disk has a diagonal scale (seesaw line), providing an accurate reading to the nearest min.
5/6
The calendar is a 4-loop spiral, the 1st being for a leap year, the 3 others for non-leap years.
'Equinoxial' is the celestial equator.
The hour disk has a diagonal scale (seesaw line), providing an accurate reading to the nearest min.
5/6
September 13, 2025 at 6:45 PM
Did you know this old name for the Big Dipper? I didn't!
The calendar is a 4-loop spiral, the 1st being for a leap year, the 3 others for non-leap years.
'Equinoxial' is the celestial equator.
The hour disk has a diagonal scale (seesaw line), providing an accurate reading to the nearest min.
5/6
The calendar is a 4-loop spiral, the 1st being for a leap year, the 3 others for non-leap years.
'Equinoxial' is the celestial equator.
The hour disk has a diagonal scale (seesaw line), providing an accurate reading to the nearest min.
5/6
When a stars crosses the meridian, hold a thread from the center, passing by the star and the "XII" on the hour disk. Then the current date on the calendar is next to the current solar time.
Some close views:
4/6
Some close views:
4/6
September 13, 2025 at 6:45 PM
When a stars crosses the meridian, hold a thread from the center, passing by the star and the "XII" on the hour disk. Then the current date on the calendar is next to the current solar time.
Some close views:
4/6
Some close views:
4/6
September 13, 2025 at 6:45 PM
It's an elaborated kind of nocturnal, its purpose being to tell the time with stars, and predict the time when a given star crosses the local meridian.
Here's Ferguson's text for the instrument:
2/6
Here's Ferguson's text for the instrument:
2/6
September 13, 2025 at 6:45 PM
It's an elaborated kind of nocturnal, its purpose being to tell the time with stars, and predict the time when a given star crosses the local meridian.
Here's Ferguson's text for the instrument:
2/6
Here's Ferguson's text for the instrument:
2/6
🔭 🧪 #astrohistory
The 'Astronomical Timekeeper', a 1770 paper instrument, by Scottish astronomer James Ferguson.
Thread 1/6
The 'Astronomical Timekeeper', a 1770 paper instrument, by Scottish astronomer James Ferguson.
Thread 1/6
September 13, 2025 at 6:45 PM
🔭 🧪 #astrohistory
The 'Astronomical Timekeeper', a 1770 paper instrument, by Scottish astronomer James Ferguson.
Thread 1/6
The 'Astronomical Timekeeper', a 1770 paper instrument, by Scottish astronomer James Ferguson.
Thread 1/6