December in Antarctica: The Sun never sets.

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December in Antarctica The Sun never sets. The
images are 1 hour apart.
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The abundances of the chemical elements in the
Sun (the cosmic abundances), relative to106 Si
atoms.
3
Light is a form of electromagnetic radiation and
consists of alternating electric and magnetic
fields
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The various types of electromagnetic radiation,
also referred to as the electromagnetic
spectrum. Note The shorter the wavelength of
electromagnetic radiation, the higher is its
energy.
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The spectrum of visible (white) light can be
separated into its various wavelength components
with the aid of a glass prism, into the colors of
the rainbow.
Definition 1 Å (Ångstrom) 10-8 cm.
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Bunsens discovery of the characteristic spectral
absorption lines of the chemical elements.
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Characteristic spectra of the chemical elements
Li, Fe, Ba, Ca and white light
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Determination of the abundances of the chemical
elements in the Sun through the measurement of
their spectra with a spectroscope mounted on a
telescope
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Spectrum of our Sun, showing the spectral lines
of the multitude of chemical elements present in
our star
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Spectrum of our Sun, indicating the presence of
the spectral lines of the chemical element Fe
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Schematic diagram of the interior make-up of the
Sun. Listed are the gas density and the
temperature as a function of depth in the
Sun. Note density of water 1, of rock
3, and of iron metal 8.
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Relationship between the 3 temperature
scales. In the sciences, the Kelvin scale is
commonly used.
13
Sunspots appear dark, because they are cooler (
4,000K) than the surrounding photosphere of the
Sun ( 5,800K).
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Sunspots occur in pairs
15
Galileo, the discoverer of sunspots
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Observation of sunspots on successive days show
the rotation of the Sun around its axis. These
observations indicate that the Sun does not
rotate like a solid body, but has differential
rotation Sunspots at Suns equator rotate once
around the Sun in 25 days, whereas those at 75
N and S rotate once around the Sun in 33 days.
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Origin of sunspots by compression of magnetic
field lines due to differential rotation of the
star.
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Sunspots occur in pairs, representing the N and S
poles of the magnetic field lines
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The number of sunspots varies from year to year,
with an 11 year sunspot cycle.
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The 11 year cycle in the frequency of sunspots,
observed continuously back to Galileo
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Granules in the photosphere of the Sun,
300-1,000 km across. Granules are convection
cells, with hotter gases ( 200K) rising in
bright centers with velocities of 2 km/sec, and
sinking in dark areas.
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Solar flare 10 Trillion megawatts
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Solar eclipse, showing solar wind. Photographed
in 1973 in Kenya.
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The Northern Lights, or Aurora Borealis