Bob Moler's Ephemeris Blog

Thursday, February 17th.  The sun will rise at 7:39.  It’ll be up for 10 hours and 33 minutes, setting at 6:13.   The moon, 1 day before full, will set at 7:24 tomorrow morning.

Four and a half years ago NASA launched a two spacecraft on a single rocket.  One was sent ahead of the earth, and the other to trail behind the earth in its orbit.  They are called Stereo, and give us a stereo view of the sun.  Earlier this month they reached points 90 degrees ahead and behind the earth.  They now cover the complete sun, front and back.  For the next 9 years we should get coverage of the far side of the sun, so we’ll see what’s brewing in the way of sunspots and other solar phenomena before they rotate around to the side that faces the earth.  The sun rotates slowly, and as a fluid body.  At the equator the sun rotates in 25 days,  at the poles it drops to 36 days.  This differential rotation causes the sun’s magnetic field to tangle and break.

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