Bob Moler's Ephemeris Blog

Ephemeris for Tuesday, November 20th.  The sun will rise at 7:46.  It’ll be up for 9 hours and 23 minutes, setting at 5:09.   The moon, at first quarter today, will set at 12:50 tomorrow morning.

It was three quarters of the moon’s revolution ago or three weeks that the moon was full and adding to the storm surge of Hurricane Sandy.  When the moon is full or new the moon’s greater tidal force adds to the sun’s giving us the highest tides called spring tides.  Tides are caused by the difference in the gravitational pull on a body from on side to the other when two bodies are close.  That’s why the moon exerts a greater tidal force than the sun, even thought its very much less massive.  Tides just don’t occur in earth’s oceans.  Jupiter’s tidal force tore apart Comet Shoemaker-Levy 9 two years before its more than 20 pieces plunged into Jupiter’s atmosphere in 1994.  Colliding galaxies exhibit tidal tails.

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

Addendum

Tidal forces on a planet, the earth for instance by the moon. Source – Wikimedia.

Comet Shoemaker-Levy 9 after a too close approach to Jupiter. The comet was torn into a “String of Pearls” by Jupiter,s immense tidal pull. They came back, crashing into Jupiter in July of 1994. Courtesy NASA Hubble Space Telescope.

Two galaxies colliding, throwing off tidal tails as they close in. NGC4686 photo courtesy NASA and the Hubble Space Telescope.

Don’t do this at home! Spaghettification by black hole. The intense gravitational gradient near a black hole will stretch a body, be it asteroid or astronaut as they approach a black hole.