flash spectrum ...photography by Robert B Slobins
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Astronomy Photos: Total Solar Eclipses

Most recent big astronomical discoveries require equipment much more powerful and and sensitive than human vision. However, the sky still provides drama, including total solar eclipses

In 1970, I traveled about two hours' distance from home to watch the 7 March total solar eclipse from the shadow track edge on Cape Cod. I found it fascinating and the solar corona was nothing like what I expected. I photographed the eclipse with a simple film snapshot camera. So in preparation for the next one, which also passed nearby two years later, I started researching.

This led me to read about eclipse spectroscopy. Astronomers used spectroscopes on the solar corona beginning in 1868. They discovered helium, the emission lines of which glowed in the spectrum and a mysterious green line no one could account for until 70 years later. That green line and others found in the coronal spectrum was proved to indicate temperatures of 1 to 2 million degrees.

American astronomer Charles A Young observed the 1870 total solar eclipse through his spectroscope. He observed that the normally observable bright continuous spectrum with dark absorption lines reversed to bright emission lines replacing the dark lines and the bright continuum going dark. This spectrum lasted only a few seconds because the moon covered the entire solar disk and then the lowest layer of the solar atmosphere, the chromosphere. Because the bright lines suddenly appeared and vanished at the start and end of totality like fireworks, Young called it the flash spectrum.

The flash spectrum is one of the rarest phenonema of observational astronomy. I made the effort to see it in 1972 by placing a diffraction grating in front of the objective of a small telescope and watching it as the moon covered the sun, effectively creating a slit. My first successful images of the flash spectrum are from the 1984 annular eclipse and the 1988 total solar eclipse. Since then I have imaged the flash spectrum at every total solar eclipse I have attended on film and later, video.

Although this website is primarily a photographic portfolio, I intend for this section to be educational, to show what one can accomplish with good preparation and develop his skills with increasing discipline and organization at total solar eclipses.




Robert B Slobins 1970-2011   |   About   |   Sitemap   |   Contact