Keysh

18 ms·

181.
by Keysh 9y ago
This nova would also have been rather low in the sky. From Seoul's latitude, the maximum altitude of the nova would have been about 7.5 degrees above the southern horizon, and not visible at all from much of Europe.
182.
by Keysh 9y ago
But it's a really bad example. In real history, Newton was able to keep quiet about views that would have gotten him fired and possibly imprisoned. Most of the "weird" Newtonian stuff the author is referring to are things New
183.
by Keysh 9y ago
No, in many spiral galaxies the spiral arms are present in older stars as well; that's why they're considered density waves in the stars. The contrast is stronger for younger stars, but it's there in old stars, too.
184.
by Keysh 9y ago
That's an exaggerated, simple model of spiral density waves; it's not a model for the Sun's orbit, which probably only varies in radius by about 10-15%.
185.
by Keysh 10y ago
Ah, I thought you were making some special argument about stars orbiting with very tilted orbits or something like that. Yes, the orbits within the inner part of a galaxy don't follow a Keplerian curve. However, at large radii most of
186.
by Keysh 10y ago
In other words, a disk-like distribution of matter does not have a uniform gravitational pull at all points of distance R from its center. You'll find it is stronger near the edge of the disk than at the same distance perpendicular to
187.
by Keysh 10y ago
There's nothing in Newtonian theory that requires light to travel instantaneously, and Ole Romer first demonstrated that light had a finite speed in the 1670s, roughly a decade before Newton published the "Principia".