New Light Through Old Plates

New Light Through Old Plates

In the Space Age the Space Cadets provide a wealth of high resolution solar images [in a whole range of sizes and eye catching colours] snapped by satellites circling somewhere above our sometimes sunny skies.

A rainbow of lunar transits

A rainbow of lunar transits as seen by NASA’s Solar Dynamics Observatory.
The observatory watches the sun in many different wavelengths of light, which are each colorized in a different color.

Dramatic Sun Storm, Partial Solar Eclipse Spied by NASA Spacecraft
Megan Gannon- 4 February 2014 – Space.com
http://www.space.com/24544-solar-flare-partial-eclipse-nasa-sdo.html

Images from the Black and White Era are hardly given a second glance in the Information Age especially when Wikipedia provides little more than thumbnail smudges.

Wikipedia 1889

https://en.wikipedia.org/wiki/Solar_eclipse_of_December_22,_1889

However, it’s worth giving these old Black and White Era images a second glance because early Photographic Plates were “usefully sensitive only to blue, violet and ultraviolet light”.

Photographic plates were also an important tool in early high-energy physics, as they get blackened by ionizing radiation.
https://en.wikipedia.org/wiki/Photographic_plate

Early photographic plates and films were usefully sensitive only to blue, violet and ultraviolet light

https://en.wikipedia.org/wiki/Photographic_film#History_of_film

However, photographic plates were reportedly still being used by one photography business in London until the 1970s, and they were in wide use by the professional astronomical community as late as the 1990s.

https://en.wikipedia.org/wiki/Photographic_plate

Therefore, although these early Photographic Plate cameras were very clunky and unsophisticated [especially compared to modern digital cameras] they did manage to capture images that included ultraviolet artefacts which are rarely seen in modern photographs.

These ultraviolet artefacts are especially evident in the Solar Eclipse images captured at the end of the 19th century with their large Halos [extending to over one Solar radius – see the 1898 eclipse example below] when compared to modern images.

Variable Eclipses

Interpreting these early Photographic Plates [that were usefully sensitive to ultraviolet light] is facilitated by referencing the ultraviolet spectrum and blue spectrum images of the January 1925 Solar Eclipse published by the Harvard College Observatory.

1925 Corona UV and BLUE

Harvard Results from Eclipse of January 24, 1925
Harvard College Observatory Circular, vol. 286, pp.1-11
http://articles.adsabs.harvard.edu//full/1925HarCi.286….1K/0000010P000.html

In the negative image [Fig 2 above] ultraviolet light is shown in black.

Perhaps the most striking aspect of this negative image is the black ring of ultraviolet light that surrounds the Solar Eclipse.

The mainstream suggests that this dark ring of ultraviolet light originates in the Sun’s Corona.

A corona (Latin, ‘crown’) is an aura of plasma that surrounds the Sun and other celestial bodies.

The Sun’s corona extends millions of kilometres into space and is most easily seen during a total solar eclipse, but it is also observable with a coronagraph.

The corona is 10−12 times as dense as the photosphere, and so produces about one-millionth as much visible light.

https://en.wikipedia.org/wiki/Corona

However, this dark ring of ultraviolet light could also be generated by the Earth’s upper atmosphere fluorescing as it is penetrated by the Solar Wind plasma [travelling at about 400 kilometres per second] which has [strangely enough] “a composition that is a close match to the corona”.

Solar Eclipse Filters

https://malagabay.wordpress.com/2015/05/20/the-solar-eclipse-perception-problem/

The solar wind is a stream of plasma released from the upper atmosphere of the Sun.

It consists of mostly electrons, protons and alpha particles with energies usually between 1.5 and 10 keV

The slow solar wind has a velocity of about 400 km/s, a temperature of 1.4–1.6×106 K and a composition that is a close match to the corona.

https://en.wikipedia.org/wiki/Solar_wind#Components_and_speed

From the European Space Agency’s Cluster mission, a new study has taken place that proposes it is easier for the solar wind to infiltrate the magnetosphere than previously believed.

A group of scientists directly observed the existence of certain waves in the solar wind that were not expected.

A recent publication in the Journal of Geophysical Research shows that these waves enable incoming charged particles of solar wind to breach the magnetopause.

This suggests that the magnetic bubble forms more as a filter than a continuous barrier.

This latest discovery occurred through the distinctive arrangement of the four identical Cluster spacecraft, which fly in a strictly controlled configuration through near-Earth space.

As they sweep from the magnetosphere into interplanetary space and back again, the fleet provides exceptional three-dimensional insights on the processes that connect the sun to Earth.

https://en.wikipedia.org/wiki/Solar_wind#Magnetospheres

Earth itself is largely protected from the solar wind by its magnetic field, which deflects most of the charged particles; however some of the charged particles are trapped in the Van Allen radiation belt.

A smaller number of particles from the solar wind manage to travel, as though on an electromagnetic energy transmission line, to the Earth’s upper atmosphere and ionosphere in the auroral zones.

https://en.wikipedia.org/wiki/Solar_wind#Atmospheres

Given that the Solar Corona is “10−12 times as dense as the photosphere, and so produces about one-millionth as much visible light” whilst the Solar Wind is concentrated into a narrow ring as it streams around the Moon [which has a mean diameter of about 3,474 kilometres] it is far more likely that this dark ring of ultraviolet light is caused by the Earth’s upper atmosphere fluorescing as it is penetrated by the Solar Wind.

The other striking aspect of this negative image [Fig 2 above] is the heavily speckled black dots [representing ultraviolet light] that dapple the remainder of the image.

This clearly confirms that some ultraviolet light reaches the surface of the Earth.

Moving on to the second Harvard College Observatory image [Fig 1 above], which is a positive [blue spectrum] photographic print of the Solar Eclipse, it is very interesting to note that this image is only lightly speckled with white dots [representing blue light].

This implies that the blue light is generated by the Earth’s upper atmosphere fluorescing when it absorbs [the more intense] ultraviolet light.

This implication is confirmed [in Fig 1 above] by the bright halo of white dots [i.e. a halo of blue light surrounding the Solar Eclipse] which is far wider that the dark ring of ultraviolet light in the negative image [Fig 2 above].

This explosive cascade of fluorescing visible light [triggered by the partial absorption of ultraviolet light in the Earth’s upper atmosphere] is clearly visible in the following early Photographic Plate image [that was “usefully sensitive only to blue, violet and ultraviolet light”] of the Solar Eclipse on the 22nd December 1889.

Solar Eclipse of 22 December 1889

The American Annual of Photography and Photographic Times Almanac – 1891
https://archive.org/details/americanannualof05newy

Unsurprisingly, this explosive Solar Eclipse image [with its very large halo] isn’t referenced by the Wikipedia entry for this eclipse [see image and link above].

Footnotes
The American Annual of Photography and Photographic Times Almanac [1891] contained the explosive image of the Solar Eclipse on the 22nd December 1889 [above] and the intriguing image of Dark Lightning referenced in an earlier posting.

1890 Dark Lightning

Page 129 – Photographs of Lightning – W N Jennings
The American Annual of Photography and Photographic Times Almanac – 1891
https://archive.org/details/americanannualof05newy

See: https://malagabay.wordpress.com/2015/05/19/dark-lightning/

For more information of the Earth’s fluorescing sky please reference the following posting:

the-fluorescing-sky

Why The Sky Is Blue
https://malagabay.wordpress.com/2013/04/15/why-the-sky-is-blue/

Another large Halo Solar Eclipse image can be found in the January 1902 edition of Popular Science Monthly

Eclipse of 1900

Recent Total Eclipses of the Sun – S. I. Bailey – Harvard College Observatory
Popular Science Monthly- Volume 60 – January 1902
http://en.wikisource.org/wiki/Popular_Science_Monthly/Volume_60/January_1902/Recent_Total_Eclipses_of_the_Sun

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Gallery | This entry was posted in Astrophysics, Atmospheric Science, Cosmic Rays, Earth, Geomagnetism, Moon, Science, Solar System. Bookmark the permalink.

4 Responses to New Light Through Old Plates

  1. Pingback: The Solar Eclipse Perception Problem | MalagaBay

  2. omanuel says:

    Thank you for pursuing quantitative information on the Sun.

  3. omanuel says:

    Precise information on solar radiation might settle a 40-year debate over the Sun’s origin, composition and source of energy:

    “Strange xenon, extinct super-heavy elements, and the solar neutrino puzzle,” Science 195, 208-210 (1977):

    http://www.omatumr.com/archive/StrangeXenon.pdf

  4. omanuel says:

    Here are a few additional references to the debate:

    01. Peter Toth, “Is the Sun a pulsar?” Nature 270, 159-160 (1977): http://www.nature.com/nature/journal/v270/n5633/abs/270159a0.html

    02. Oliver K. Manuel and Alberto Boretti, “Yes, the Sun a pulsar,” Nature (submitted 12 Dec 2012) http://dl.dropbox.com/u/10640850/Yes_the_Sun_is_a_pulsar.pdf

    03. “The sun’s origin, composition and source of energy,” in Lunar and Planetary Science XXIX, 1041 (CD-ROM, March 16-21, 2001) http://www.omatumr.com/lpsc.prn.pdf

    04. “Neutron repulsion,” The Apeiron Journal 19, 123-150 (2012) http://tinyurl.com/7t5ojrn

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