SpaceX lost 38 Starlink Satellites due to a CME

I wrote last year about the effect of CME on the thermospheric density and what are the effects on satellites inside the thermosphere, typically at the altitude of the Starlink satellites. You can find this post here. Solar cycle 25 is well underway now, and from the look of it, it looks like the sun is in a strong unrest. It might be a very active solar cycle, that some predictions made put it at the same level than the cycle 20, which peaked in the 70’s. Little known fact about the 20th solar cycle: one of the strongest storm …

Continue Reading

Special blog shout-out: https://ciechanow.ski/

So this post is a simple shout-out to some other blog I discovered a few months ago. At the time, I was browsing hacker news and saw this post about optics. Great! I love hacker news for this. They mostly have posts about computers and programming but every now and then, there is a post about something totally unrelated, be it optics, physics, environment, etc… but always some quality content. This time, it was this blog: https://ciechanow.ski/, and I have to say, I am amazed by the work this guy has been doing. His blog is filled with in depth …

Continue Reading

Haidinger’s Brush Or How To See Polarization

I have always been interested with optics and vision. My path led me to a more technological approach of optics, aka photonics, but I still am fascinated by the process of vision. How the image is formed in the eye, how it is interpreted in the brain and so on. This led me to learn a few things that apparently are not so well known about our own eyes. One of these things is the subject of this post: Haidinger’s brush. To start, it should come to no surprise to you that our eyes are sensitive to colours. We have …

Continue Reading

NEOWISE seen from my garden

I know, this comet was seen 1 and a half year ago, but I didn’t had a blog then, so I have to do it now… I simply wanted to show off some of my pictures I took with a simple EOS100D and a 18-55 mm zoom lens. Nothing fancy really, but it was enough to capture the comet NEOWISE in July 2020, which was the brightest comet in a while visible in the northern hemisphere. These are a bunch of pictures, all taken with a simple EOS100D at various focal length. I stacked roughly 10-15 pictures for each final …

Continue Reading

That Time When We Lost The Position Of Some Satellites

I wrote about Carrington events here, just a few days before the solar cycle 23 unleashed some strong storm with an X1 flare the 28th October and several other CMEs the next days… Fortunately, the impact on earth was minimal: It was a mostly a miss. But it sparked some wonderful display of aurora in the last days of October. See here and here for some nice images. Still, the storm had an impact in the sky, more precisely, on the satellites in orbit that had either some unwanted reboot, or even in some case, thrusters being spontaneously triggered. One …

Continue Reading

Laser physics: gain medium and population inversion

Continuing the series on lasers. In the first part, I went fast over plenty of concepts and left others on the side because they were not necessary to get a global understanding of lasers. Here, I want to get a little deeper in some specific concepts. I want to talk more in details about the gain medium of a laser and why population inversion is a vital concept. For now, I have been relatively simple on the gain medium characteristics… I have considered a simple material with two atomic energy levels, and I have been assuming that the transition is …

Continue Reading

Checking dimensions in equations

Short post this week. I want to talk about a simple concept that is extremely useful in physics and other fields of applied science. Especially those fields working with equations to calculate anything that has a physical meaning to it, like a speed, a voltage, a weight.. As a physics student, our teachers would usually spend a few minutes talking about how it is extremely important to check dimensions. Back then, I was listening and not really thinking how that would help me concretely to find the answer to the problem they were giving us. I would always be puzzled …

Continue Reading

An introduction on laser physics

So I want to start a series of posts that will focus mostly on lasers, what they are, how they work, what are the most important elements, etc… It can still evolve. Some prerequisites first: To fully understand what I will write, here, it definitely helps to be familiar with a few concepts and bases from electromagnetism and optics, obviously. I’ll try to explain these concepts along the way of course. Nevertheless, even if you don’t have the necessary background, keep reading. I’ll try to keep it simple and limit the mathematics to a minimum. It’s no surprise that lasers …

Continue Reading

The dangers of solar eruptions: the dreaded Carrington event

I am a fan of disaster movies. I have grown in the 90’s and 00’s, at a time where Hollywood started a trend of summer blockbusters that usually involved alien invasion, or volcanoes and other gigantic threat that was supposed to threaten the existence of Humanity. We had it all: Independence Day, Volcano, Armageddon, Deep Impact, 12 monkeys, etc… Spectacular and frightening. Most of these movies are special, in the sense that they depict events that are very unlikely to happen during our lifetimes. I mean volcanoes are a real threat, there is the whole super-volcano threat in the Yellowstone …

Continue Reading

A new surprising sorting algorithm

Just a small post today. I stumbled upon a paper [1] on ArXiv recently on a surprising sorting algorithm that was discovered pretty recently (in October 2021). Here is a quick implementation I wrote in Python: It’s not the most efficient algorithm obviously, as it will always do n2 comparisons. It is an O(n2) algorithm in the best case and worst case scenario. There are much more advanced algorithms out there that go down to O(n log n) in average, so much faster and more efficient. This algorithm is more like a curiosity, based on how simply the sorting is …

Continue Reading