Posts Tagged ‘Corona’

08/03/2017 – Ephemeris – The surreal world of totality

August 3, 2017 1 comment

Ephemeris for Thursday, August 3rd. The Sun rises at 6:31. It’ll be up for 14 hours and 33 minutes, setting at 9:04. The Moon, half way from first quarter to full, will set at 3:43 tomorrow morning.

The brief world of solar eclipse totality is one everyone should experience at least once in their lifetime. The duration of totality is so brief that one cannot really absorb it all. As the Moon covers the last of the Sun’s bright photosphere there is a chill as the Sun’s heat is extinguished. Darkness of a deep twilight descends. Street lights come on, cocks will crow, as animals take the darkness as the approach of night. The approaching shadow of the Moon can be seen. During totality the Sun’s corona can be seen as a silvery apparition around the black spot of the Moon that’s covering the Sun’s disk. Bright planets and some stars will appear in a surreal image in the darkened sky, but the horizon is bright. Then suddenly the diamond ring appears and it’s over.

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


Total eclipse scene

Screen capture from a video of a total solar eclipse of November 2, 2013 at the small village of Mikongo in the equatorial African country of Gabon. This video shows the eclipse expedition of Williams College led by Professor Jay Pasachoff. © 2013 Michael Zeiler. See the video at

Check out the Great American Eclipse web site.

Simulation of the August 21, 2017 totality

An animation of Stellarium’s version of the sky during totality of the August 21, 2017. My personal caveats based on 4 total eclipses are that Venus is always visible, Mercury only sometimes. I’ve never seen a star. Also the Sun’s corona is a whole lot brighter than seen here. See the image above.  Click on this image to enlarge.

Diamond Ring

Diamond ring at the end of totality of the total solar eclipse July 10, 1972. Credit Bob Moler.

Additional notes:

The Sun’s corona is perfectly safe to view without a solar filter.  Actually the Sun will disappear in solar eclipse glasses and projection viewers.  That’s the time to look at the Sun with the naked eye or binoculars.  However, when the corona brightens around the right side of the Moon, and the red chromosphere appears, drop the binoculars for the bright diamond ring will quickly appear.

The corona for the quiet Sun stretches out on either side of the Sun, with little at the poles.  The active Sun, near a sunspot peak, tends to have a roundish corona.  Below is the corona last evening via the Solar and Heliospheric Observatory (SOHO).

SOHO coronagraph

The black disk on the stalk is the occulting disk, hiding the bright photosphere and producing an artificial eclipse.. The white circle is the size of the Sun’s disk. Credit ESA and NASA

Part of the inner corona close to the Sun is covered by the disk.  That is what is easiest to see during a total solar eclipse.

For a couple of minutes just before totality starts and again after it ends strange bands of light and shadow will flit along the smooth surface of the ground.  They’re called shadow bands.  I’ve seen the effect on a large concrete parking lot, an airport tarmac and a softball infield.  The nearest thing I’ve seen to it the shadow ripples on the bottom of a swing pool on a sunny day.  I finally saw them on my fourth total solar eclipse and two subsequent annular eclipses* which were viewed from or near smooth surfaces.  It’s a product of air turbulence and shows up at night in the twinkling of stars.

* An annular eclipse is one in which the Moon is too far, and thus too small to completely cover the face of the Sun.  The central part of this type of eclipse leaves a ring or annulus of the bright Sun surrounding the Moon.