Blogs by Hilary Hopkins

Closer to Home

Seeing the Eclipse, Just Barely

November 11, 2013 / Seeing the Eclipse, Just Barely

It was a near thing, seeing our tenth total solar eclipse.  I mean we almost did not see it.  I kept telling myself what I told the “eclipse virgins” in our group of 96: “Well, the eclipse happens whether you see it or not, and even if you do not see the disk of the sun, you will experience the ultimate scariness as light drains away so suddenly, all at the wrong time of day.”  But it was hard believing my own advice

It’s true, though: our first eclipse, in Hawaii in 1991, was observed from the pitching, rolling deck of a very small boat amid a rainstorm.  At totality, the light went a creepy green and yellow and I knew something bad had happened, even if I couldn’t see what.

Anyhow, this time, we were on a small ship south of the Cape Verde islands, off Senegal.  For several days prior to eclipse day the captain and the onboard astronomers consulted nervously with land-based weather gurus.  The general site had been chosen with great care to maximize clear-weather probability along the path of totality, which is a pretty narrow band.

But the past few days had been cloudy and rainy.

And of course in that part of the world there was a concern about pirates…so the captain really didn’t want to venture his ship too far south to escape clouds only to encounter pirates.

A real nail-biter.

So what causes a total solar eclipse?   Simply put, it is when the Moon is at exactly the right place between Earth and Sun such that the Moon’s disk completely covers the Sun’s photosphere (that’s the visible surface of the Sun).   What’s left of the Sun to see is the corona (that’s the upper atmosphere of the Sun, which glows).

At totality you can also see other wonderful sights: Baily’s Beads, which are a series of bright spots at the edge of the eclipsing sun (just before totality).  The beads are where the deepest valleys on the Moon’s edge allow just a smidgen of sunlight to pop through before the Moon finally covers the Sun.   At the very last second before totality, you get to see the Diamond Ring, the last bit of sunlight passing through the deepest valley on the edge of the Moon.

And as totality is complete, there’s the chromosphere (my favorite), a thin glittering pink and orange and red band around the profoundly-black thing, like a terrible hole, that is the now-covered Sun.   Sometimes there are prominences, too, red and orange flares or arcs of monstrously-hot gases leaping up from the Sun and appearing at the edge of the black disc.

There’s lots more stuff to know about eclipses. 

For instance, the longest possible length of totality is about seven and a half minutes, the shortest, only a few seconds.  The totality we are waiting for today is about one minute long.

There are anywhere from two to five eclipses every year visible somewhere on Earth (not all of them are total, though).  However, if you never left your home, you would have to wait about 375 years between eclipses visible at that same spot.   Better to travel to see them! 

The path of totality, the narrow band on Earth where any one eclipse is seen as total, is pretty small—a maximum of 167 miles wide.  Our Cape Verde eclipse path is only 34 miles wide.

It takes quite a while—in the case of this one, about 90 minutes—for the Moon to completely cover the Sun, in a slow dance.  The first instant of that bite the Moon takes out of the Sun is called First Contact, and it’s a thrilling time. 

But to return to our tenth eclipse, on board the little ship, in the early morning.  Being a veteran of these events, I made very careful preparation. 

From the trip journal:

5:30 am   I have secured our spot on deck with two chairs, tied together against the wind with my scarf, and even with cushions!  When I crept out this morning all was dark on deck, and only a few people were about; we passed each other in silence.  The air outside here is mild, and the sky, dark.  We will see.  Now to get a coffee.

5:40 am  Got coffee and cookies and I am back outside here in my nice corner.  Now I can see clouds, faintly, and a gray-on-black horizon.  We are moving, very slowly, and the ship is bucking and lurching.

This morning the Laws of Physics, and the movements of the objects in the Universe dictated by them, will enable a brief event of vanishing consequence, doubtless common all over the Universe, except that we, an exotic species, are here to see it.

5:55  It’s possible a few patches of blue might appear.  Small, tiny ones.  I don’t have much hope that I will see totality, this time, but it’s gonna happen, behind clouds, anyway.

6:15  Hmm.  Now totally overcast and a ragged raincloud looms in the east, not too wide, but putting down heavy rain.  If it and we intersect, I will just grab our cushions and bring them to a dry place for a while.

6:25  Not looking great.  More, bigger rain clouds to the south, though a few bits that look as if they could conceivably clear.  But we’ve never had such difficult weather, except that first time, in the downpour, in Hawaii.

7:15  Well, for a brief few minutes the sun appeared, veiled.  We are surrounded by clouds of differing thicknesses, and there was a sprinkle of rain.  First Contact in about an hour and three-quarters.

8:31  An hour to First Contact.  Looking, well, fairly hopeful or somewhat hopeful.  People are gathering on upper decks but we are here in our snug place on Deck 3.

8:52  Looking a little better, although the sun is only visible through cloudiness.  The Captain is doing his best to put the ship in a good place, but there will be a limit to success.  I shall just sit here, in my chair by the railing, and listen to the slosh of water along the ship. 

9:16  Fifteen minutes to First Contact.  Still a hazy view of sun, surrounded by clouds, but.

9:29  First Contact!   The first bite is from the top limb [edge] of the sun, and I barely make it out through my binoculars, taped with #14 welders’ glass [this is what we use to protect our eyes].

10 am  I believe the lights on the foam and waves that the ship is making has dimmed; more pewter than silver.  [There is usually a variety of peculiar light effects visible through the time to totality.]

10:19  Reflection of the sun on the water is flattened and oily.  Forty-one minutes to total.  I go up a deck to try to show this light effect to people but no one seems really to notice except one man who also uses the word “oily,” to my delight.  But there are very few light effects, I think because so little of the eclipsing sun is visible, and there are so many clouds scattering its light.

10:25 The Captain repositions the ship to try to get in that tiny blue hole up ahead and over there.

10:35  Twenty-five minutes to go and clouds developing quickly.  I don’t think we will get this one.

10:45  Fifteen to go.  Darkening all around but still in clouds.  Not many light effects.  I doubt we will see the black disc or the corona.  I can squint and see a very very thin crescent now.  The light is flowing away.

10:50  Well…too bad..this will not happen for us…

10:55  silvery-gray light
ALL RIGHT HERE WE GO—
THE HUGE GLOWING PEARL IN THE CLOUD
HERE I GO----AWAY----
BIG HORRIBLE EYE LOOKING DOWN AT US
TOO TOO DARK TOO DARK
YES YES YES YES IT IS HAPPENING

NO NO NO NO NO DON’T DO IT DON’T DO IT DON’T DO IT DON’T DO IT

THE LAST DROP OF LIGHT IS SUCKED INTO THE BLACK

THE CHROMOSPHERE GLITTERS PINK

…and within a minute the light comes back and a fervent cheer rises from the people, and all goes again only in reverse, but few give attention, and celebration begins.

To behold this I am here and how fortune has blessed me, once again!

Comments

  • Julia Green 09:56am, 06/30/2014

    Hi Hilary—

    could you add me to your subscription list?  Your front page subscription doesn’t work with my browner—

    Thanks—Julia Green

Comments?

Remember my personal info?

Notify me of follow-up comments?