Stars / Astronomy / Astrophotography / Telescopes / Astro

Somewhere, someone very big is flipping pancakes.

https://www.theguardian.com/science/2019/feb/04/milky-way-is-warped-and-twisted-not-flat

First ever picture of a black hole expected at 2pm tomorrow:

https://www.youtube.com/watch?reload=9&v=Dr20f19czeE

I thought the EUCO Brexit extension announcement was at 5pm, not 2pm?

Boom.
Tish.

Here's a very good explanation of what you're looking at...

https://www.youtube.com/watch?v=zUyH3XhpLTo

Shouldn't there be a black hole in the picture where the black hole is? :)

it's right there in the top-right corner, you just can't see it..!

Is it the one right next to the image of the black Arrospok that you can't see, either?

for some reason i'd never visualised a blackhole as a sphere before, had always thought of them as 2D flat circle .... are they spheres ?

now even more confused

time to watch tonights bbc programme on them and the photo, to see whats what

The event horizon for a non-rotating black hole is a sphere. I never learned about rotating black holes so not sure in that case - it might be an oblate spheroid. At the centre of the event horizon the maths says there is an infinitely dense zero-volume point.

Mind-bending

The easiest way to imagine a black hole is to imagine some food and then to imagine @hippy hovering nearby.

There you go, doesn't take any imagination.

They're inherently 4-dimensional, that is you don't get very far without considering them as 4D objects described by GR.

For fun you can use different co-ordinates to map things out. And interestingly, within the event horizon every direction you turn to points towards the centre hence no escape!

On possible mining in the solar system:

https://www.theguardian.com/science/2019/may/12/protect-solar-system-space-mining-gold-rush-say-scientists

A bit far away, of course, but interesting.

There's more minerals in the asteroid belt than have ever been mined on Earth, the first, maybe second person who organises an economic operation will have more money than anyone else on the planet...

Also, speaking of the mega rich, the starlink constellation passes overhead tonight.

I'd never heard of that Starlink thing (I think). Sounds completely bonkers.

https://en.wikipedia.org/wiki/Starlink_(satellite_constellation)

Sounds like the future then...
Spacex are rapidly making commercial rocketry a reality. They have a turn over of more than 2 billion dollars already.

Ha, I'd say we have more than enough environmental problems at the moment for rocketry not to add to that ...

Can it ever be sustainable?

Presumably, there's stuff like 'oh, but we'll use rockets to repair the atmosphere' or something?

Not something I've been following at all.

Can it ever be sustainable?

Some rockets can be propelled by liquid hydrogen + oxygen producing plain old water. You can generate hydrogen and oxygen by electrolysing water with solar or wind power. So that'd be perfectly renewable and zero carbon (excluding the building of various parts of the system).

Satellites etc. are surely worth their CO2 cost anyway. We're better off with a communications satellite or a CO2-measuring satellite than some dudes jetting off on holiday.

we need to explore new planets cause we're killing this one by using all the resources to explore other planets

Pffft, they sound like a load of frankenrockets. :)

A space elevator could also be built to be CO2 neutral and is ultra-cool. Doubt we'll see it in our lifetimes...

Ha, I'd say we have more than enough environmental problems at the moment for rocketry not to add to that ...

There are around 100 launches per year, I reckon that's a drop in the ocean next to India's and China's, and therefore the rest of the world's, carbon output.

Well, at the moment, I'm sure, but unless you use a lot of frankenrockets it'll be as with all motorised transport innovations--they're relatively harmless curiosities at first, and then usage explodes until you get to successive breaking points. The upshot is usually just more and more travel beyond any reasonable utility that one could rationally defend. As I joked earlier, there may well be environmentally useful applications for rocketry, but would they really happen in favour of middle-aged billionaires going up for their fifteen minutes in space?

More about hydrogen production using excess electricity (with some fudgy numerical estimates). A really good solution IMO.

https://www.carboncommentary.com/blog/2017/7/5/hydrogen-made-by-the-electrolysis-of-water-is-now-cost-competitive-and-gives-us-another-building-block-for-the-low-carbon-economy