Bob Moler's Ephemeris Blog

This is Ephemeris for Monday, October 27th. Today the Sun will be up for 10 hours and 23 minutes, setting at 6:38, and it will rise tomorrow at 8:15. The Moon, 2 days before first quarter, will set at 10:31 this evening.

There is much more matter in the universe than we can see with our telescopes. This began to be apparent back in the 1930s when Fritz Zwicky discovered that galaxies in clusters were moving too rapidly. They should be flying apart, but they were not. Later, Vera Rubin found that stars moved around the center of galaxies at pretty much uniform speeds. One would expect stars farther from the center of a galaxy to move slower. So there must be some matter out there creating gravity by its mass that was invisible. This became what we call dark matter. No one knows exactly what it is, though there have been several hypotheses put forth. It can be detected by its warping of space-time, due to its mass, to distort the shapes of the galaxies beyond it.

The astronomical event times given in this blog are for the Traverse City/Interlochen area of Michigan (Lat 44.7° N, Long 85.7° W; EDT, UT – 4 hours) unless stated otherwise. Times will be different for other locations.

Addendum