Hey astronomers, I have a question.

@mrundkvist @nomenloony no, there is too much empty space in galaxies

@mrundkvist because there's actually so much space in a galaxy it's actually highly unlikely stars would ever come close enough. If the stars were a metre across there'd be around 120km apart on a smaller scale.

@vicgrinberg @nomenloony

Imagine being Erwin Hubble in a really fucked up galaxy, looking out at all the nice ones next door, and not being able to understand your own galaxy's structure at all.

@mrundkvist @nomenloony we actually still learning a lot of new things about our own galaxy's structure and don't fully understand it! It's generally just hard to know more about the galaxy we are stuck jn vs the ones we see from the outside: https://www.esa.int/ESA_Multimedia/Images/2025/01/The_best_Milky_Way_map_by_Gaia

@mrundkvist @vicgrinberg @nomenloony it's genuinely difficult to study the far side of the Milky Way because of all the stars, gas, and dust between us. This is a pain for studying the history and evolution of the Milky Way. So in some small way we are living in that reality

https://en.wikipedia.org/wiki/Zone_of_Avoidance

@mrundkvist @jenbanim @nomenloony no, wrong. Here a good description of how density waves work https://astronomy.swin.edu.au/cosmos/*/Density+Wave+Model

@jenbanim @mrundkvist @vicgrinberg @nomenloony
I guess it's a bit like trying to understand the layout of your own city when you're stuck in a single street corner, unable to move. But you can get nice aerial pictures of other cities.

@jannem @jenbanim @mrundkvist @nomenloony that's a really nice comparison!

@mrundkvist
No, because it's happening on completely different time scales. Galaxy dances happen in millions of years, your life may barely extend 100 yrs.

Some events may happen in your time: a deadly meteor strike. But this time the probability works in your favour: to hit your planet is against a lot of odds - but not completely impossible.

@mrundkvist Not by much. Galaxy merges are a slow processes taking eons. The chances of two stars colliding are low. However there is a possibility of close stellar encounters increasing, but again not by much. It does depends on which part of the galaxy the planet is and which around which star it revolves around. There is a hypothesis of owl type galaxies having 3 or more SMBH. If that is the case then position of the star w.r.t the SMBH does impact the planet.

@vicgrinberg @mrundkvist @nomenloony fav case is the edge-on warp deducted from Gaia data

https://www.esa.int/Science_Exploration/Space_Science/Gaia/Gaia_discovers_our_galaxy_s_great_wave