Solar Atmosphere - The atmosphere of the Sun. An
atmosphere is generally the outermost gaseous layers of a
planet, natural satellite, or star. Only bodies with a strong
gravitational pull can retain an atmosphere. Atmosphere is used
to describe the outer layer of the Sun because it is relatively
transparent at visible wavelengths. Parts of the solar
atmosphere include the photosphere, chromospheres, and the
Solar Limb - The apparent edge of the Sun as
it is seen in the sky.
South Atlantic Anomaly - The region over the South
Atlantic Ocean where the lower Van Allen belt of energetic,
electrically charged particles is particularly close to the
Earth's surface. The excess energy in the particles presents a
problem for satellites in orbit around the Earth.
Spectral Line - A line in a spectrum due to the
emission or absorption of electromagnetic radiation at a
discrete wavelength. Spectral lines result from discrete changes
in the energy of an atom or molecule. Different atoms or
molecules can be identified by the unique sequence of spectral
lines associated with them.
Spectrograph - An instrument that spreads light
or other electromagnetic radiation into its component
wavelengths (spectrum), recording the results photographically
Spectrometer - An instrument for measuring the
intensity of radiation as a function of wavelength. See
Spectrum - Electromagnetic radiation
arranged in order of wavelength. A rainbow is a natural spectrum
of visible light from the Sun. Spectra are often punctuated with
emission or absorption lines, which can be examined to reveal
the composition and motion of the radiating source.
Speed of light - 186,000 miles per second (or
300,000,000 meters per second). The universal "speed limit" that
is the fastest that anything can go.
Spin - The characteristic of a particle
that causes it to rotate about an axis in a consistent
Strong Force - A fundamental particle. There are
six quarks (but only five have been observed) plus their
antiquarks. Each quark and antiquark exists in three "colors."
Subatomic particle - Any particle smaller than an
Sunspot - A temporary disturbed area in the
solar photosphere that appears dark because it is cooler than
the surrounding areas. Sunspots consist of concentrations of
strong magnetic flux. They usually occur in pairs or groups of
opposite polarity that move in unison across the face of the Sun
as it rotates.
Superconductor - Force that binds quarks and holds
the nucleus of an atom together. It is the strongest force in
Surface Plot - A three-dimensional plot mapping
the intensity of radiation from a region as a distorted surface.
More intense radiation is represented by higher points on the
surface. Therefore, regions of intense radiation resemble
mountains on the earth.
Scalar - Quantity, like distance, that has
only a magnitude, or size.
Schematic Diagram - Representation of electric
circuit using symbols.
Scientific Notation - Numbers expressed in form M * 10
^ n , where 1< M < 10, and n is an integer.
Scintillation - Flash of light emitted when
substance is struck by radiation.
Second - SI unit of time.
Second Law of Thermodynamics - Heat flow only from region of
high temperature o region of lower temperature.
Secondary Coil - Transformer coil in which varying
EMF is induced.
Light Colors - Yellow, Cyan or Magenta Light.
Secondary Pigment - Red, Green, or Blue Pigment.
Self-Inductance - Induced EMF produced in coil by
Semiconductor - Material in which electrical
conduction is smaller than that in a conductor, but more than in
Series Circuit - Circuit in which electrical
current flows through each component, one after another.
Series Connection - Arrangement of electrical devices
so that there is only one path through which current can flow.
Short Circuit - Low resistance connection between
two points, often accidental.
SI - Internationally agreed -upon
method of using the metric system of measurement.
Significant Digit - Reliable digits reported in a
Harmonic Notion - Motion caused by linear restoring
that has a period independent of amplitude of motion.
Simple Machine - Machine consisting of only one
lever, inclined plane, wedge, screw, pulley, or wheel and axle.
Sine - The ratio of the opposite side
and the hypotenuse.
Sliding Friction - Force between two surfaces in
Slope - Ratio of the vertical separation,
or rise to the horizontal separation, or run.
Solid - State of matter with fixed volume
Sound Level - Quantity measuring logarithm of
sound intensity in decibels.
Spark Chamber - Device used to detect path of
charged subatomic particles by a spark that jumps along path of
ionization created in a gas.
Specific Heat - Thermal energy needs to change
temperature of unit mass of substance one Kelvin.
Spectroscope - Device used to study spectrum of
Spectrum - Collection of wavelengths in
Speed - Ratio of distance traveled to
Light - In vacuum, 2.9979458 * 10^8 m/s.
Spherical Aberration - Inability of spherical mirror to
focus all parallel rays to a single point.
Standing Wave - Wave with stationary nodes.
Static Friction - Force that opposes start of
motion between two surfaces.
Step-Down Transformer - Transformer with output voltage
smaller than input voltage.
Step-Up Transformer - Transformer with output voltage
larger than input voltage.
Stimulated Emission - Emission of photon from excited
atom caused by impact of photon of same energy.
Strong Nuclear Force - Force of very short range that
holds neutrons and protons in nucleus together.
Superconductor - Electrical conductor that has no
resistance and low temperatures.
Surface Wave - Wave on surface of liquid with
characteristics of both longitudinal and transverse waves.
Symmetry - Property that is now charged when
operation or reference frame is charged.
Synchrotron - Device to accelerate particles in
which particles move in circular path.
System - Defined collection of objects.