Indeed, there is a programme using Copernicus images to monitor the algal blooms in the Baltic Sea, aiming to provide warnings in case the blooms drift close to coasts where they can be harmful to human health.

https://marine.copernicus.eu/services/use-cases/monitoring-harmful-algal-bloom-baltic-sea-hab-risk-service

Cyanobacteria are not technically algae, as they're prokaryotes, meaning they don't have a nucleus, while true algae are eukaryotes and do.

They use light-absorbing pigments like chlorophyll to convert sunlight into energy, & that gives them their blue-green colour.

And while such blooms are natural, they can be heavily enhanced by fertilisers in agricultural run-off, so they're not necessarily a good sign.

Still, they do make for spectacular images from space.

Once in a while, it pays to look at images from satellites that point down instead of up

So I thought I'd share this rather striking picture of a cyanobacteria algal bloom in the Baltic Sea, overlaid with some summer clouds.

It spans a 90 x 90km area east of Stockholm & was taken by the ESA-operated Sentinel-2A satellite at 10:10 UTC on 23 July 2019.

Credit: contains modified Copernicus Sentinel data (2019), processed by Mark McCaughrean, CC BY-SA 4.0

#EarthObservation #SpaceSciencejoy

A momentary burst of sunshine

While the day looked set to be overcast & cold the whole time, there was some sun in the late afternoon, coinciding with today’s 50km ride

Kept the chill off, at least mostly, although it did little for the many wet & mucky bike paths out there ‍️

#CyclingLife ‍️
#Photography

@raederle I can't begin to imagine how hard that must've been to witness at that age & how difficult it must've been for the teachers in all those schools faced with a class of pupils after seeing such an event.

@birchbirch Apparently not – when the newsletter was printed & circulated on site, some people complained to me about the apparently callous transition. But it was entirely unintentional & the consequence of numbness I felt on that day.

@jrm And as if to prove that insensitive snark wasn't invented when the internet came along, there were many very poor state jokes made after the explosion, things I remember hearing but won't repeat here.

Humans really can be the worst of species at times ...

@JeremyMallin That must have been quite shocking.

Indeed, if I recall correctly, many school children were watching the launch live, as Christa McAuliffe was on-board, to be the first teacher in space.

Very traumatic, I expect.

@Snoeksen Indeed. And arguably, it's not much safer today – while computing power may have improved greatly in the past 40 years, certain aspects of going to space are remain very much rooted in "analogue physics", & also there's no guarantee at all that engineering, management, & oversight systems improve with time.

We will found out when the first group of tourists dies on one of the billionaire tech bros machines – these are not famously people that listen to dissenting employees.

@friz As flawed as the shuttle was, it was hugely important machine & in many ways, still unrivalled, despite the endless bleating of the billionaire space bros.

Unfortunately, I never saw a launch, but I was lucky enough to visit KSC in 2010 as part of an ESA-NASA bilateral & take a tour through the OPF.

Discovery was there & we got very up-close & personal, walking underneath it. I may or may not have (gently) touched the thermal tiles & undercarriage

@birchbirch It was a very difficult day.

I had just finished writing my regular piece about my fellow students for the ROE newsletter. I added a “in memoriam” sentence about the Challenger crew at the top, but was enough shock that I didn’t reread what came after in my original article before sending it in.

When it was printed, I was embarrassed by the jokey tone of the main article – it was completely inappropriate coming after that sombre opening

@simonzerafa Indeed – it was a very difficult day.

Of course made worse later when the Rogers Commission found that senior management & engineering hubris played a significant role, ignoring known SRB flaws & launching on a day well outside the rated conditions. The political pressure to up the launch cadence was also in the background.

And having worked 15 years for a space agency, I certainly recognise some of the non-technical sociological issues that can lead to disaster.

On this day, forty years ago: 28 January 1986.

I was working on my astronomy PhD in the terminal room at the Royal Observatory Edinburgh.

Someone came in & told us the awful news. After so many launches & astronauts, we’d grown blasé & didn’t pay much attention anymore.

That changed in 73 seconds on that cold day & we learned again that space is hard.

I still remember their names:

Onizuka, Smith, McAuliffe, Scobee, Jarvis, Resnick, & McNair.

Ad astra, STS-51L Challenger crew

#space