Plate 7045 from the SDSS BOSS mission. We’re doing a lab with it today to show Hubble’s Law.
I am mildly obsessed with mechanical pencils and drafting pencils.
This needs to be translated for the simple English Wikipedia. One day, if I can do that, I’ll understand it. Today is not that day. https://en.wikipedia.org/wiki/Phase_space#Conjugate_momenta
An animation showing the variable RR Lyrae Stars in globular cluster Messier 3.