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A | B | C | D | E | F | G | H | I | J | K | L | M
N | O | P | Q | R | S | T | U | V | W | X | Y | Z
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A
active region: An
area of the solar atmosphere where the Sun's magnetic
field is concentrated. The concentration and bipolar
nature of the magnetic field results in the formation
of dark areas such as sunspots and
bright areas known as facula.
These regions also produce flares and plages.
All-Sky imager: An
instrument built to take images
of the sky from horizon to horizon
in order to observe the full sky
from a point on Earth.
alluvium: Deposits
of sand, earth
or clay carried
by rivers or floods.
altitude: The
vertical height
above Earth's surface.
angstrom: A
unit of length
equal to one hundred-millionth
of a centimeter.
astronomy: The
science that studies
the Solar
System and beyond.
astrophysics: The
study of the history,
structure and dynamics
of objects in the
Universe.
Athabasca,
AB, Canada: A
town in the Alberta
province in the
country of Canada.
atom: Atoms
are very small,
about 0.1 nanometers
in diameter. The
building block,
for all matter
in the Universe.
aurora: Light
radiated by ions
and atoms in the
Earth's upper atmosphere,
mostly in polar
regions, the result
of bombardment
by energetic electrically
charged particles
from the ionosphere
and magnetosphere.
Aurora
Borealis: Aurora
that occurs in
the northern hemisphere
(see Northern Lights).
auroral
arc: Auroral light in
the form of a regular bow,
which often extends east-west.
auroral
arc filaments: Very narrow
auroral arcs on the order
of 100 meters in width.
Auroral
Australis: Aurora that
occurs in the southern hemisphere
(see Southern Lights).
auroral
band: Auroral structure,
either as "homogeneous
bands" or as "rayed
bands," resulting when
an auroral arc loses its
regular shape.
auroral
eruption: A sudden change
in the appearance of the
aurora from a motionless
single auroral arc to many
moving auroral forms. This
is also called aurora substorm
onset.
auroral
kilometric radiation: Intense
radio waves whose wavelength
is of the order of a kilometer,
emitted from regions above
the ionosphere where the
aurora is (apparently) accelerated.
auroral
oval: The instantaneous
configuration of the global
aurora.
auroral
ray: Lines of auroral
light, usually sharply defined,
extending along Earth's
magnetic field lines. |
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B
bar magnet: A
magnet in the shape of a bar with two poles (north
and south).
bow shock: The
shock wave that flanks the magnetosphere
on the day side. It causes the solar
wind flow to slow down and flow around
the magnetosphere.
breakup
phase: A phase
in the development
of aurora known
as an auroral substorm
in which many forms
of aurora move
rapidly and the
auroral oval expands
both towards Earth's
magnetic poles
and equators.
Bulbuls: A
type of songbird.
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C
Cal
Day: A day in April when departments at the University
of California at Berkeley
showcase their instructional products and give information about
their programs.
charged particles: Particles with positive
or negative charge, for example electrons, protons,
or ions. Particles with like charges repel and
opposite charges attract.
cholera: An infectious
disease of the small intestine characterized by vomiting, diarrhea,
muscle cramps, and severe dehydration.
chromosphere: The part of the Sun's (or another star's)
atmosphere between the photosphere and the corona.
compass: A
tiny magnet that aligns itself with
Earth's magnetic field and points north.
convection: Circulation
of a fluid or gas.
corona: The
Sun's outer atmosphere,
with a temperature
of greater than a
million degrees,
that gives rise to
the solar wind.
coronal
mass ejection: A
vast magnetic blob
of plasma that erupts
from the Sun's corona
and travels through
space at high speed.
Coronal mass ejections
may cause intense
geomagnetic storms
when they strike
the Earth and accelerate
vast quantities of
energetic particles
in both interplanetary
space and the magnetosphere.
cosmic
ray: An extremely
energetic (relativistic)
charged particle.
cosmology: The
study of the history,
structure and dynamics
of the Universe.
Cro-magnon: An
early form of
human who lived in
Europe in the late
Paleolithic
Period.
cow
magnet: A strong
little bar magnet with
smooth edges used to
treat a cow or bull
who has eaten scraps
of metal. All the metal
(nails, bits of barbed
wire) in the leathery
first stomach clumps
together around the
cow magnet so it does
not harm the insides
of the cow.
current: Moving
charged particles such
that opposite charges
are moving relative
to one another, i.e.
not at the same speed
or in the same direction.
current
disruption: A process
that occurs in Earth's
magnetosphere whereby
current on the equatorial
plane is disrupted
and forced to move
along Earth's magnetic field into the upper atmosphere into the nighttime auroral
oval.
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D
data: The outcome
of a set of measurements or information from which inferences may
be drawn, explanations made, or theories constructed.
dawn: The
time of day immediately preceding sunrise.
dipole: A
compact source of magnetic force, with two magnetic
poles.
disk: The
visible surface of the Sun projected against the
sky.
dome: A
vaulted roof having a circular, polygonal, or elliptical
base and a generally hemispherical or semispherical
shape.
dusk: The
time of day immediately following sunset.
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E
electric
field: A map of the direction and magnitude of electric
forces around charged particles.
El Niño: A warming of the ocean off the
western coast of South America. It occurs every 4 to
12 years. It can create unusual weather patterns in various
parts of the world.
excited
state: A state in which an atom or
molecule has absorbed a discrete amount
of energy from a particle (including light
particles).
extreme
ultraviolet: Electromagnetic radiation, invisible
to the naked eye, with wavelengths shorter than ultraviolet
radiation and longer than x-rays. These wavelengths
are mainly responsible for the existence of the ionosphere. |
F
facula: Brighter-than-average
regions on the Sun's surface that typically appear near
a group of sunspots just
before the sunspots themselves appear.
flare: A
sudden outburst of energy from the Sun
that occurs near concentrated magnetic
fields (known as active
regions ) on the Sun's visible
surface. Flares emit high-energy charged
particles (ions and electrons) and all
forms of electromagnetic radiation into
space. |
G
gamma rays: High-energy
electromagnetic radiation, invisible to the naked eye,
with wavelengths shorter than x-rays. Gamma rays are
emitted from the Sun during the most energetic flares
on the solar surface.
gauss: A
unit of magnetic field strength.
GEMS: An
acronym that stands for Great Explorations
in Math and Science. This is a program
at the Lawrence Hall of Science at
the University of California at Berkeley
for science educators. It includes
professional development
for educators around the United States of America as well as teacher's
guides on a variety of science topics.
GEONS: An
acronym that stands for Geomagnetic Event Observation
Network by Students. This is a network of schools,
teachers, and students participating in the magnetometer
science of the THEMIS NASA mission.
geomagnetic
field: The Earth's
magnetic field.
geomagnetic
storm: A worldwide large disturbance in the
Earth's magnetic field, accompanied by intense
auroras in the northern and southern polar regions
and intensifications of the particle radiation
trapped in Earth's magnetosphere (the Van Allen
belts).
geophysics: The
study of the nature of
processes occurring on
Earth.
growth
phase: The first
phase in a substorm
when the magnetotail
becomes thinner and
the auroral oval expands
southward.
granulation: The
cellular structure
of the photosphere. "Granules" are
formed by convection,
each one is quite large,
about 700 to 1000 km
(400 - 600 miles) in
diameter.
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H
hard
drive: A device found in a computer used to
store information.
heliopause: The outer
edge of the heliosphere, where the solar wind runs into the interstellar
medium. At the heliopause, the pressure of the solar wind balances
that of the interstellar medium.
homogeneous
arc: An auroral arc that is uniform
in structure throughout.
hydrogen: The
smallest and most common
atom in the Universe. |
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I
infrared
radiation: Electromagnetic radiation, invisible
to the naked eye, with wavelengths longer than visible
light and shorter than microwaves.
interplanetary
magnetic field: The magnetic field
among and between planets, brought
out from the Sun by the solar wind.
interstellar
medium: Electrified
gas and dust between
the stars.
ionosphere: The
region of the Earth's
upper atmosphere
containing a small
percentage of free
electrons and ions
produced by photoionization
of the constituents
of the atmosphere
by solar ultraviolet
radiation at very
short wavelengths
(<100 nm).
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K
Kelvin (K): A
unit of temperature with a magnitude equal to that of
the degree Celsius, and based on a scale in which 0 K
is absolute zero (-273.15 °C). A temperature expressed
in Kelvins is equal to the Celsius temperature minus
273.15. |
L
limb: The edge
of the Sun or planet visible to an observer or instrument. |
M
magnet: The
magnetic field among and between planets, brought out
from the Sun by the solar wind.
magnetic
field: A map of the direction and strength
of magnetic forces around any object (such
as the Sun or planet) that is magnetic.
Magnetic fields are caused by electric
currents in the Sun.
magnetic
field line: Lines
drawn to represent the
magnetic field around
an object.
magnetic
pole: A magnetic
pole of a magnet is the
point near the end of
the magnet,
at which the magnetic
force seems concentrated.
magnetic
reconnection: A process
that takes place in plasmas
with very few collisions
such that the charged
particles are attached
to magnetic fields until
the fields reconnect
and the particles can
move from one magnetic
field line to another.
magneto-hydrodynamic: A
mathematical theory to describe charged particles
and magnetic fields when there are very few collisions.
magnetometer: An
instrument to measure
magnetic fields.
magnetopause: The
boundary of the magnetosphere,
lying inside the bow
shock, usually about
10 Earth radii toward
the Sun. The solar wind
is deflected inside the
bow shock to flow around
the magnetopause in the
magnetosheath.
magnetosheath: The
region between the bow
shock and the magnetopause,
characterized by very
turbulent plasma. For
Earth, along the Sun-Earth
axis, the magnetosheath
is about two Earth radii
thick.
magnetosphere: The
region surrounding a planet
within which the planetary
magnetic field is the dominant
force on electrically charged
particles that can be trapped
within the magnetosphere, making
radiation belts like Earth's
Van Allen belts.
magnetotail: A
comet-like extension of a planet's
magnetosphere formed on the
planet's dark night side by
the interaction of the solar
wind and the magnetosphere.
It can extend hundreds of planetary
radii away from the Sun.
mass: Stuff
in the Universe that has
weight in a gravitational
field.
the Moche: A pre-Incan
civilization, they inhabited
the coast of northern Peru
from about 200 B.C. to
600 A.D.
model: A
description of a system or phenomenon
that accounts for its known or
inferred properties and may be
used for further study of its
characteristics.
molecule: Multiple
atoms that are connected to one
another. |
N
nimbus
clouds: Rain clouds, usually with a low dark layer.
noctilucent
clouds: Clouds formed at extremely high-altitude
that shine at night. A bit of a mystery, scientists
aren't sure why or how they are formed.
Northern
lights: The common name for Aurora
Borealis, aurora seen in the Northern
Hemisphere.
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O
onset: The
time in a substorm between the growth phase and breakup
phase when the aurora changes from a stationary arc or
auroral oval to an active aurora that expands both toward
the poles and the equator.
orbit: The
path of an object in space as it revolves
around another object. |
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P
parallax: The
difference in apparent direction of an object as seen
from two different locations.
patchy
aurora: Aurora that appears as
large patches in the sky that turn
on and off every 3 seconds.
pedagogical: Of,
relating to, or characteristic
of the art or profession
of teaching.
penumbra: A
dark region that
surrounds an even
darker central area
of a sunspot.
photosphere: The
visible portion of the Sun.
plage: Bright
regions of gases
with concentrated
magnetic fields in
the solar chromosphere.
They appear near
groups of sunspots and
in the regions surrounding
sunspots that are
about to emerge.
plasma: A
low-density gas in
which the individual
particles are charged
and which contains
an equal number of
positively charged
ions and negatively
charged electrons.
plasmasphere: A
region of the inner magnetosphere that
contains relatively cool (low energy) and dense plasma.
This area can be considered an outer extension of the ionosphere.
preliminary
design review: The first NASA
review during the second phase of
a mission in which the designs of
the mission, from instruments to
the satellite bus (body), are evaluated
by an independent review team.
prominence: Complex
structures of relatively
cool, dense solar material
that extend into the
outer chromosphere
and inner corona. They
are generally static
and believed to be
supported by magnetic
forces. They can appear
as loops on the edge
of the solar disk or
limb. Their shape is
probably controlled
by the Sun's magnetic
field. Sometimes they
erupt, often in association
with coronal mass ejections.
psychology: The
study of mental processes
and behavior. |
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R
radiation: Radiation
has two different meanings. One is the stream of particles
emitted by decaying nuclei such as uranium. This energy
often takes the form of alpha or beta particles, or
neutrons. A second use is as part of the term “electromagnetic
radiation," which refers to energy traveling in
the form of electromagnetic waves or photons. For example,
yellow light is a form of electromagnetic radiation,
as are radio waves and x-rays.
radiation
belts: Regions of high-energy
particles trapped by the magnetic
influence of the Earth. These belts
are sometimes called "Van Allen" belts
because of their discovery in 1958
by Professor J.A. Van Allen. Radiation
belts are composed of electrons,
protons, and smaller numbers of other
ions.
radio-tomographic
imaging: A technique
for the imaging of
the spatial distribution
of ionospheric plasma
density.
rayed
arc: An auroral arc
that looks like a curtain
with distinct vertical
lines along the arc.
real-time
image: An image that can be studied or observed
as they are being generated.
recovery
phase: The final phase in a substorm.
relaxed
state: The state of an atom or molecule when
it has released all of its discrete energy initially
absorbed by a particle that collided with the atom
or molecule.
Rudyard
Kipling: A British writer and poet.
His best known works are The Man Who Would
Be King (1889), The Jungle Book (1894),
and Kim (1901). |
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S
satellite: An
object that was launched into orbit around Earth or
around another celestial body.
simulation: A
mathematical description of a system
or phenomenon that is studied using
a computer.
solar
activity: Activity
of sunspots, flares
and CMEs that
follow the solar
cycle.
solar
cycle: A predictable 11-year cycle
when defined by solar activity, including
the number of sunspots, flares, and
CMEs that follow this cycle. When
defined by the solar magnetic field
directions, the cycle is 22 years long.
solar
flare: An explosive
release of energy
of the Sun.
solar
maximum: A period
of increased solar
activity when the number
of sunspots reaches
a maximum in the 11-year
solar cycle.
solar
minimum: A period
of decreased solar
activity when the number
of sunspots reaches
a minimum in the 11-year
solar cycle.
solar
wind: The charged
particles (plasma),
primarily protons and
electrons, that are
continuously emitted
from the Sun and stream
outward throughout
the solar system at
speeds of hundreds
of kilometers per second.
Southern
lights: The aurora
seen in the Southern
hemisphere.
space
science: The study
of the Universe from
Earth's upper atmosphere
to the far reaches
of the Solar System.
space
weather: The conditions
in the Solar System
(the solar wind,
Earth's magnetosphere,
etc.) at a given time
and place, with respect
to variables such as plasma density and temperature, and magnetic
field strength and direction.
spatial
resolution: The smallest discrete step in space
that an instrument can measure.
star: A
hot ball of gas that
shines from its own
energy.
substorm: A
global development
of the aurora and Earth's
magnetosphere that
has three main phases:
growth, break-up, and
recovery.
sunspot: A
region of the solar
surface that is dark
and relatively cool;
it has an extremely
high magnetic field.
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T
temporal
resolution: The smallest discrete step in time
that an instrument can measure.
terrella
experiment: An experiment created
by K. Birkland to prove that the aurora
was due to charged particles following
magnetic field lines to the upper atmosphere.
triangulation: Measurement
of the distance of a planet or nearby star by sighting
its apparent position against background stars from
two or more separate locations.
Tribal
college: A college located on
Native American tribal lands.
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U
ultraviolet
light: See ultraviolet
radiation.
ultraviolet radiation: Electromagnetic
radiation, invisible to the naked eye,
with wavelengths shorter than violet
light and longer than x-rays.
umbra: The
dark central area of a sunspot.
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V
visible
light: Light with wavelengths that can be observed
by the human eye.
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W
white light: Electromagnetic
radiation composed of all wavelengths of light that is
visible to the naked eye (red through violet).
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X
x-rays: High-energy
electromagnetic radiation, invisible to the naked eye,
with wavelengths shorter than ultraviolet radiation and
longer than gamma rays. |
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