Nuclear Ninety North Eclipse of the Midnight Sun August 1st, 2008

Eclipse Day

Shortly before the eclipse was to begin, the sky was partly cloudy and we banked our hopes on the ability to run for a hole in the clouds.

In the distance off the stern of the ship, the northwest coast of Novaya Zemlya was visible. This island was used between 1955 and 1990 as a test site for atmospheric and underground nuclear explosions, including the 50 megaton Tsar Bomba in 1961, the largest nuclear explosion of all time. Much of the island is a restricted area where landings are forbidden, and hence our eclipse observations would be from shipboard.

Shortly after first contact, the partially eclipsed Sun was visible from time to time through the clouds. At other times, denser clouds would render the disc entirely invisible. All of the photographs of partial phases were taken using only the clouds as a solar filter: no neutral density filter was used on the lens.

A patch of blue sky was visible on the horizon (note the direct sunlight falling on the ocean in the distance), but the clouds appeared to be advancing toward it faster than the ship could travel at maximum speed. At this point, consequently, the ship remained stationary in the hope of a clear patch appearing.

With the clouds continuing to obscure the partial phases of the eclipse and totality approaching, the captain was persuaded to make a run for the clear spot. He turned the ship, placing the Sun off the port bow (confounding a number of photographers, including this one, who had set up their equipment based on the expected bearing of the Sun at totality), and headed for the break in the clouds at maximum speed, around 21 knots. This resulted in a brisk breeze across the deck and a strong vibration as the ship reached its maximum hull speed. This would have consequences for eclipse photography, as we shall see.

We continued to race for the hole in the clouds at maximum speed. Note how the light had begun to change as the crescent Sun narrowed.

As the crescent narrowed, some beautiful colour effects were visible in the clouds. Here, the Sun seems to be surrounded by a circular rainbow. One astronomer remarked that this photo “looks like a nebula”.

Almost there! Dismayingly, as the light dimmed toward second contact, we still hadn't reached the hole in the clouds, although the clouds obscuring the Sun had begun to thin noticeably.

Bailly's Beads (the last vestiges of the uncovered photosphere shining through lunar valleys) highlighted the onset of totality. Note the chromosphere, shining in its characteristic hydrogen alpha red light, on either side of the beads.

Moments later the photosphere was completely obscured. This very short (1/4000 second) exposure captures the inner corona and a prominence at the 1 o'clock position.

As the Moon's disc advanced across the Sun, this 1/800 second exposure captured the inner corona and the bright prominence at the upper right. Note the coronal brush structure at the poles.

This picture is far from perfect, but it's the best approximation of any I got of the visual appearance of the eclipsed Sun. Taken through the thin clouds obscuring the Sun and handheld at 1/20 of a second to minimise the impact of the shuddering vibration of the ship's deck (which, coupled by a tripod directly to a camera mounted on it, is disastrous for long focal length lenses and/or long exposure times), it's a little blurred in the vertical axis by the vibration but not that bad as far as the rendering of the corona. This was taken not long after totality, and the chromosphere imparts a reddish hue to the just-eclipsed lower left limb of the Sun. North and South polar brushes are visible, as well as the two prominent coronal streamers on the left side of the Sun. The streamer at the 7 o'clock position extended visually for several solar diameters—much farther than is perceptible in this picture.

Moments before third contact, the chromosphere became visible in a large arc at the right side of the Sun.

Third contact! The diamond ring (with a modest punctuation into beads by lunar mountain peaks on the profile) heralds the end of totality. At this instant, the chromosphere, a prominence, and inner corona remain visible, within milliseconds to disappear to the earthbound unaided eye until the next total eclipse.

The high-resolution photographs during totality were taken with a Nikon D300 camera and Nikkor 500 mm catadioptric “mirror lens”, which provided the equivalent of 750 mm focal length on a 24×36 mm film camera. The same lens was used to photograph the 1999 and 2001 solar eclipses.

After totality the Sun was, of course, in a pristine blue sky. Folks engaged in the traditional entertainment of making small apertures with their fingers and projecting images of the crescent Sun on the ship's deck.

by John Walker August 20th, 2008

This document is in the public domain.