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07/07/2017 – Ephemeris – Tonight’s topic: Dark Matter

July 7, 2017 1 comment

Ephemeris for Friday, July 7th. Today the Sun will be up for 15 hours and 24 minutes, setting at 9:29, and it will rise tomorrow at 6:05. The Moon, 2 days before full, will set at 5:48 tomorrow morning.

This evening the Grand Traverse Astronomical Society will hold its monthly meeting at the Northwestern Michigan College’s Rogers Observatory at 8 p.m. with a program featuring Dr. David Penney and his talk Dark Matter: What Is It? What Does It Mean? Dark matter, whatever it is appears to be the stuff that holds the universe together. We can’t see it, but we can see its effects in the rotation of galaxies, the motions of galaxies in clusters and their distribution and how it distorts the images of galaxies beyond it. After the talk, at 9 p.m. there will be a star party to view the heavens including the Moon, Saturn and Jupiter. The observatory is located south of Traverse City, on Birmley Road between Garfield and Keystone roads.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Dark matter filament

Dark Matter filament bridge between two galaxy clusters, discovered by Jörg Dietrich and his colleagues at the University of Michigan. The blue color is added to show the presence of dark matter. See the text below. Image from http://www.outerspacecentral.com/dark_matter_page.html.

Dark matter is detected by the distortions it creates in the distant galaxies behind it.  These galaxies are not visible in the scale of the image shown.  The gravitation of dark matter distorts spacetime as predicted by Einstein’s general theory of relativity, which distorts the shapes of the galaxies behind it.