Tag Archives: eclipse

Eclipse meteorology

“Plan of Observations. -The meteorological observations proposed were especially directed towards the subjects of barometric pressure, air temperature, humidity, solar radiation, and wind velocity. The instruments located on the top of the tower were in charge of Mr. Rotch, and those at its base Mr. Upton.”

―Winslow Upton and A. Lawrence Rotch, Meteorological and other observations made at Willows, California, in connection with the total solar eclipse of January 1, 1889. Annals of the Astronomical Observatory of Harvard College, Vol. XXIX, 1893.

Diagram of the solar eclipse
Drawing of the total solar eclipse of January 1, 1889

The scientific instruments used during a solar eclipse include telescopes with a protective filter to reduce the brightness of the Sun to protect an astronomer’s eyesight. The earliest known image of the Sun taken by a camera was recorded in 1845. But it was still common for scientists to draw sketches with pencil and paper as it has been done for centuries. The above image is based on a number of photos taken with different exposure times. The short exposures record bright features but leave out many of the fainter ones. The longer exposures cause the bright features to be overexposed but reveals subtle details. The sketch above is a composite of these different photographs.

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A Minimal Penumbral Lunar Eclipse and Two “Meteorocre” Shooting Star Displays

“What’s in a name? That which we call a July Full Moon
By many other names would shine as bright.”

My apologies to William Shakespeare, but I simply couldn’t resist mangling the above famous quote from Romeo and Juliet.

Full Moons have a myriad of names. Here in the United States the colonists adopted many of them from Native Americans, predominantly the eastern Algonquin nation. While these descriptive names have become the primary ones by which we identify each Full Moon, many other names have been ascribed to them.

For example, the July Full Moon is usually called the Full Buck Moon. This name was one brought over by the colonists from Europe. Male deer in both Europe and North and South America shed their antlers yearly, and by July a new set has emerged. Another old-world name for this Full Moon is Hay Moon, signaling when the hay field had been reaped. And finally Thunder Moon has been used for obvious reasons during northern hemisphere summer months.

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Chromospheric lines

“These are some of the problems in connection with the sun which are being investigated at the present time. Their complete solution will help to interpret the mystery, not only of the sun itself, but also of that type of stars of which the sun is a representative.”

―Frederick Slocum, The Study of Solar Prominences. Popular Astronomy, July 12, 1912.

Frederick Slocum (Brown University undergraduate class of 1895) received the first Ph.D. in astronomy at Brown in 1898 and served as assistant professor of astronomy from 1899 to 1909. He then became professor of astronomy at Wesleyan University in 1914 where he planned and supervised the construction of Van Vleck Observatory. The image below shows Slocum observing with a spectroscope attached to the main telescope at Ladd Observatory.

observing with a spectroscope
Observer Frederick Slocum using a spectroscope on the 12″ refractor at Ladd Observatory. March 15, 1905.

This spectroscope was made by the scientific instrument maker John Brashear of Pittsburgh in 1891. It is used to study the spectrum of colors in starlight. It could also be mounted on a table top to examine the spectrum of a chemical which is done to calibrate the instrument. During this era professor Winslow Upton used it in an attempt to predict rain.  It uses a prism or diffraction grating to disperse the light into a rainbow pattern of colors. This reveals dark Fraunhofer lines in the spectrum that can be used to identify the chemical elements present in the Sun or a distant star. Each chemical element has a unique pattern of these dark lines where specific colors are missing.

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The dark side of the Moon

Automated instruments on the roof of Ladd Observatory monitored the sky during the total lunar eclipse of Sept. 27-28, 2015. First there is a wide field sky camera. It has a fish-eye lens which can capture an image of most of the sky above Providence. The second is a sky brightness meter which is used to monitor light pollution.

Eclipse sky
An image from the sky camera during the total phase of the eclipse. (Click on the image to see a time lapse video.)

The full Moon is usually so bright that it overwhelms the sensitive camera causing the images to be overexposed. During the eclipse the Moon was dark enough that the only artifact in the image above is a thin vertical line where one column of the digital camera was saturated by the moonlight. The camera is more sensitive than the human eye allowing the Milky Way to be seen during the total phase of the eclipse. The time lapse video contains 3,625 still images. Each second of the movie shows about 5 minutes of changes in the sky.

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