Category Archives: Science

Bitcoin and the blockchain

Two interesting articles from this week’s Economist:

The promise of the blockchain: The trust machine. “The technology behind bitcoin could transform how the economy works”.

Blockchains: The great chain of being sure about things. “The technology behind bitcoin lets people who do not know or trust each other build a dependable ledger. This has implications far beyond the cryptocurrency”.

A week of optical phenomena in the sky

Tuesday, June 23rd, around 5:30pm: supernumerary rainbow (Regenbogen mit Interferenzbögen):

Thursday, June 25th, around 6:30am: sun dog (Nebensonne). I saw another one just before sunset that day, but didn’t take a photo because I didn’t have my camera with me.

Sunday, June 28th, just before 4:00pm: complete 22°-halo, pale sun dogs on both sides, plus an almost complete parhelic circle (22°-Halo, Nebensonnen, Horizontalbogen. Why didn’t I bring my camera? I captured part of the display with my phone, though…

Here’s the upper part of the 22° halo:

And here’s part of the 22° halo again on the upper right, plus part of the parhelic circle on the left:

(I hid the sun behind a street light.)

Sonnenfinsternis

After missing the previous total solar eclipse that was visible in Germany in 1999 due to excessive cloudage in Bonn I was doubly lucky today: There wasn’t a single cloud in the sky, and my timetable at school allowed me to watch the entire eclipse from start (9:29am) to finish (11:49am).

I had a pinhole camera, eclipse glasses and a sun projector at my disposal. Many students also had brought eclipse glasses and/or pinhole cameras, and the beginning of the eclipse happened just before the end of recess, so everyone was keen on taking a first look.

The sun projector proved to be a huge hit as it provided the largest picture of the sun with a diameter of about 5cm; here’s a (bad) photo I took of the projected image around 11:24am, only half an hour before the end of the eclipse:

While discussing the upcoming eclipse with my tenth grade yesterday we noticed the pattern of circles that the sun was making on the classroom floor. I realized that the holes in the blinds act like pinhole cameras and predicted that the circles would turn into crescents during the eclipse, but I think most of the students did not quite believe me until they saw it today – there were rows upon rows of tiny eclipses all over the floor and walls:

One student showed me this photo she had taken and wanted to know why the sun seemed to be whole while the eclipse was visible above and to the right:

It turns out that the sun was still so bright that that its shape was not accurate*, but the lens flare showed the eclipse – how cool is that?

*I know there’s a proper term for this that refers to the fact that when too much energy reaches one pixel it overflows to the neighboring pixels, thus altering the form of the lightsource you’re photographing, but I can’t remember it right now.

Zum Abschluss noch ein paar Links auf deutsch für die geneigten Leser aus der Nachbarschaft:
Sonnenfinsternis am 11. August 1999 und Sonnenfinsternis vom 20.03.2015 (heute), Lens Flare bzw. Linsenreflexion

Besondere Erwähnung verdienen die Sonnentaler – für die gibt es keinen englischen Begriff, so weit ich weiß. Gemeint sind die Lichtflecken, die ein dichtes Blätterdach oder auch kleine Öffnungen in Rollläden/Jalousien verursachen und die heute während der Finsternis als kleine Sonnensicheln zu sehen waren. Die Entstehung beruht auf dem gleichen Prinzip wie die Bildentstehung bei einer Lochkamera.

Per Anhalter durch Deutschland

HitchBOT – A robot exploring the world

“I am hitchBOT – a robot from Port Credit, Ontario. From July 27, 2014 to August 21, 2014, I hitchhiked over 6,000 km from Halifax, Nova Scotia to Victoria, British Columbia. In just 26 days I hitched a total of 19 rides to reach my final destination – Victoria, British Columbia. […] This February, my adventure continues as I explore Germany. My journey will begin in Munich on February 13, 2015 and conclude in Munich on February 22, 2015. […] Join me as I learn more about Germany, including the people, language, and culture.”

I’d love to give HitchBOT a ride if he visits Palatinate!