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Solar History Timeline
Our understanding of the sun and its many details is part of a much longer history of events that had to unfold. These pages will take you on a journey from the birth of the cosmos, to the most recent discoveries about our nearest star.
The Modern Era of Solar Physics
1939 -
J. Dellenger describes how short wave outages caused by solar
flares acting on the ionosphere.
1939 -
Proton aurora discovered.
1940 - Easter Day shortwave disruption by major flare. The term 'radio
blackout' first appears in a New York Times article on January
14.
1941 - Major shortwave disruptions during World War II
activities.
1943 - Sunspots hamper radio transmission of Allied invasion of Italy on
September 3.
1942 - S.E. Forbush detects Ground Level Event (GLE) radiation
enhancement due to energetic protons associated with a solar
flare.
1947 - World-wide radio traffic is blacked out by a 'sunspot' on March
8th. Radio fadeouts are reported over Shannon Airport in Ireland
on July 19th Airplane radio traffic interference is extensive but
no blackouts during July 20th storm. Radio blackouts across the
Pacific Ocean and extending to New York are reported during the
August 23 storm.
1947 - Giovanelli proposes that solar flares related to solar magnetic
changes.
1949 - Astronomer Grote Reber detects a major radio burst from a flare,
3 minutes before the actual flare is detected by telescopic
study
1951 - L. Biermann discovers solar wind using comet tails
1953 - Dungey proposes that solar flares caused by opposing magnetic
fields on the sun.
1956 - P. A. Sweet proposes that flares originate in the activity of magnetic
fields above the active areas of sunspots.
1957 - Waldmeier discovers coronal holes
1957 - Hannes Alfven proposes that the solar wind was
magnetized.
1957 - World-wide radio fadeout lasts several hours on April 16th .A
36-hour blackout cripples England on June 20th
1958 - Van Allen Belts discovered by Explorer I satellite.
1958 - Severny proposes magnetic shock wave theory of flares, and that
flares occur along the magnetic 'neutral line'. Sweet develops a
'flux interchange' theory which shows how the flaring process
leads to a simpler-shaped field after the flare event.
1958 - Eugene Parker predicts solar wind should exist
1959 - Shortwave blackout over North Atlantic on March 29th . Shortwave
blackout over Asia, Europe and North America on August
18th,
1959 - Mariner 2 spacecraft detects the solar wind
1960 - Tommy Gold and Fred Hoyle propose that all of the energy released in a
flare was previously stored in a magnetic field.
1960 - Moreton observes time-lapse solar activity which shows that a
flare explosion produces waves in the solar atmosphere much like
a bomb's concussion wave, and that these waves travel at 1000
km/sec and sometimes cause other solar disturbances in their
wake.
1961 - Magnetopause boundary detected by Explorer 10
spacecraft.
1962 - Warwick discovers Polar Cap Absorption events, and shows how
these are related to powerful solar flare proton streams with
energies of 10 MeV.
1963 - Eugene Parker calculates how magnetic reconnection might work in a solar
flare, and concludes that it takes too long to explain the sudden
changes seen in typical solar flares.
1963 - Type IV radio flares are found to be related to proton acceleration.
Magnetic reconnection theories get a reprieve.
1963 - Furth proposes a new 'tearing mode' which disrupts current sheets
and leads to solar flares. The time it takes reconnection to
happen is an average time between the Parker and Petschek
processes.
1964 - Using a more detailed approach to describing magnetic
reconnection than what Furth used in 1963, Petscheck recalculates
how Parker's reconnection process would work, and concludes that
reconnection could easily happen as fast as actual flare events
are observed.
1967 - Alfven and Carlquist propose a 'current disruption' process which can
also act very quickly, but makes different assumptions than what
Parker and Petschek made in describing the release of magnetic
energy.
1968 - OGO-5 satellite detects magnetic activity in the geotail
region
1968 - Bumba shows that flares have a statistical preference for active
regions where two bipolar spot groups are merging, with one
developing in the central regions of another.
1968 - David Rust confirms that explosions occur at neutral points in
magnetic fields of sunspots and satellite spots. The vanishing
magnetic energy is equal to the kinetic energy of the gases and
the electromagnetic energy in x-rays and gamma rays. These
observations seem to confirm the Parker/Petschek reconnection
idea
1971 - Najita and Orrall and Hudson propose that white light flares are caused
by bombardment of the upper photosphere by down-streaming proton
or electron beams from the site of the flare event in the top of
the coronal loop.
1971 - Lin and Hudson propose that hard X-ray bursts during the impulsive
phase of a flare are evidence for 10,000 to 100,000 volt electron
beams.
1971 -
Brown proposes the 'non thermal' flare model where magnetic
energy causes an electrical current to flow down a magnetic loop
until it collides with the photosphere at the footpoints, and
heats the gases to x-ray energies to cause the flare.
1971 -
OSO-7 satellite discovers 'Coronal transients'
1972,
August 4 - Apollo 17 major flare
1974 - Altschuler shows that the coronal magnetic field changes
drastically in strength and geometry around a flare region. Low
level magnetic loops disappear and this means that currents of
electricity also disappear at the time of a flare.
1989, March - 8-13 Major solar flare, X15 - Space Shuttle pressure sensor
malfunction reported, but then sensor returns to normal so flight
not aborted.
2001, April
2 - Solar flare X20 - major flare
2003,
November 4 - Major solar flare X34 ends a period of solar storms
which began October 28th. Astronauts on the International Space
Station take cover. Many newspaper accounts.
November
11, 2003 - Solar flare reproduced under laboratory conditions by
a team of scientists at the Culham Science Centre near Oxford,
England.
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Image
Credits: Proto solar nebula: Spitzer Space Telescope
(http://www.spitzer.caltech.edu/Media/041209telecon/ssc2004-22a.shtml)
Stonehenge and Stars: Knowth.com
(http://www.knowth.com/wallpaper.htm) Solar Flare diagram : Space
Sciences Lab, UC Berkeley.
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