If you haven't heard, rapper B.o.B thinks the Earth is flat.

We know this, because he tweets about it constantly, and is currently crowdfunding to try and get a satellite out to space to "help B.o.B find the curve!" No, we're really not making this up.

As we explained last week, putting aside the ridiculousness of the whole thing, actually seeing the curve on ground level can be a little difficult for us puny humans, but that doesn't mean it's not there. As Fiona MacDonald explained:

"The explanation for that is that Earth is really, really big, and its curvature is tricky to detect for us tiny humans on ground level. But we do already have plenty of photos of it from space, like the famous and breathtaking Blue Marble photo, taken in 1972 by the crew of Apollo 17."

If you were really looking forward to B.o.B's satellite, I wouldn't recommend getting too excited just yet.

It's not going well – at the time of writing he's raised just US$4,700 of a US$1 million target since the campaign began last week.

But we've got some good news for B.o.B: He might not need that satellite after all, because we've got astronauts that have literally 'seen the curve' – and they're happy to tell him all about it.

I can save BoB a lot of money- The Earth is round. I flew around it. https://t.co/F7qAovPEng @bobatl @BBCWorld — Terry Virts (@AstroTerry) September 27, 2017

Terry Virts was the pilot of STS-130 aboard the Space Shuttle Endeavour, and was commander of the ISS for Expedition 43. He'd definitely know if the Earth was flat.

Then Apollo 11 astronaut Buzz Aldrin jumped in to back up Virts – and it was too good.

I did too. It's called an orbit: the curved path of a celestial object around a star, planet, or moon. https://t.co/h8GQJadfxD — Buzz Aldrin (@TheRealBuzz) September 27, 2017

And finally – our favourite recently retired astronaut Scott Kelly came in with a beautiful timelapse video from the ISS.

Show you the curve? Here you go @bobatl! One full orbit around Earth. Maybe donate funds raised to #PuertoRicoRelief https://t.co/bhJSXfwYXL pic.twitter.com/rFAysS2clc — Scott Kelly (@StationCDRKelly) September 27, 2017

What a champ.

So – although most of us would be super excited to get replies from three separate astronauts in one day, B.o.B honestly seems pretty nonplussed.

People usually discourage you from doing something when they have something to hide ? — B.o.B (@bobatl) September 29, 2017

Ah well, some people just won't be reasoned with.

We're not going to link to B.o.Bs campaign, so instead, please enjoy this video of the Aurora Borealis from space… complete with the curve.