Just to plan ahead a little gonna start a thread of threads here of Science Topics I talk to @melissasage about that make her freak the fuck out and demand i make a post about

Thread 1: Astronomy

So this one was inspired from one of @dankwraith's posts earlier today about heliocentricism vs geocentricism, because fun fact: the sun isn't even the thing at the centre of the solar system

if you do the maths, turns out that just the mass of jupiter is enough to move the system centre of mass (COM) outside the sun by about 40,000 km

this then led to the question: how often *is* the system COM inside the sun?

so for this lil problem i decided that Jupiter and Saturn are the only planets that exist, and that they travel in perfectly circular orbits around the sun, because by mass turns out that nothing else in the system really matters

(fun sligihtly existentially terrifying fact: the entire mass of the earth moves the system COM by less than 500km, aka less than One Diameter Of France)

(making assumptions like this is basically 99% of all physics btw, turns out pretty much all science is just making progressively better approximations until you're happy with it)

Anyways, after doing some more maths it turns out that if Jupiter and Saturn are on opposite sides of the sun, then the COM is inside the solar radius. And since that arrangement is known to occasionally happen, the sun *is* **sometimes** the centre of the solar system, and heliocentricism *is* **sometimes** ***mostly*** correct!

So how often does this happen anyway? there's a particular angle of Jupiter-Sun-Saturn at which the COM is right at the sun's edge that i can't be bothered to calculate rn, so for now let's just look at how often that particular syzygy (alignment of 3 astronomical bodies (also one of my fave words i mean look at it)) happens.

Based on the respective orbital periods of the different planets, the Jupiter-Sun-Saturn syzygy happens roughly every 19 years, 7 months, 18 days, 20 hours and 30 minutes, which is therefore roughly how often Copernicus and Galileo were right. Like 20 year broken clocks.

Btw if that time seems kinda weirdly short to you, bear in mind that anything going in orbit around anything else always has to travel faster than you'd think.

To explain why orbital movement happens so damn fast, to go into orbit around the earth you basically have to be going fast enough that the curvature of the earth bends the ground away from you about as fast as you fall towards it.

This is why the ISS goes at mach fucking 23 and orbits earth every 92 minutes. You literally have to throw yourself at the ground and miss!