Catégorie : Astronomy

How do big telescopes look through the atmosphere – Adaptative Optics 101

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Continuing my series of post covering my talk from last Christmas about the use of lasers in space and astronomy. The topic today is adaptative optics. I’ll explain the reason why we need it, and how it works in simple terms. Enjoy. No surprise: telescopes are the main tool of astronomers. Since Newton, we have built countless telescopes of various sizes and shapes. And lately, we even send them to space. We have Hubble, the JSWT for the more famous, and a lot of other space telescopes less known. But why sending them to space? After all, space is difficult. …

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What is the difference between a regular lamp and a laser? A brief history of Optics and Lasers

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So this post and a bunch after this one are from a talk I presented at the end December on the topic of lasers in space and astronomy. The target the audience was members from astronomy groups in the region with some knowledge of optics but not necessarily lasers and the curious people that might be interested but have a physics background from high school. I tried to make it interesting for a wide audience, and I would say that it is accessible to some degree to someone in high school, maybe earlier? Anyway, the goal was to be entertaining, …

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Diffraction patterns in astronomical imaging

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The first image from the James Webb Space Telescope (JWST) was uncover a few days ago [1]. This is truely an incredible image, showing the galactic cluster SMACS 0723, which is slowly becoming the de-facto target for newly deployed space telescopes as it was imaged by Hubble, Planck and Chandra before JWST. This image in particular took the JWST 12.5 hours of exposure to be able to see these objects as they are so dim in the sky. The best way to see how much of an achievement this is, is to compare it to the previous picture, taken by …

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SpaceX lost 38 Starlink Satellites due to a CME

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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 …

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NEOWISE seen from my garden

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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 …

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That Time When We Lost The Position Of Some Satellites

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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 …

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The dangers of solar eruptions: the dreaded Carrington event

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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 …

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