EMS Flashcards
Electromagnetic Spectrum
the entire distribution of electromagnetic radiation according to frequency or wavelength
Spectroscopy
the branch of science concerned with the investigation and measurement of spectra produced when matter interacts with or emits electromagnetic radiation.
Continuous Spectrum
a spectrum where all wavelengths are present (ROYGBIV)
Emission Spectrum
a spectrum produced by a hot gas (black background with bright lines)
Absorption Spectrum
a spectrum produced by a cool gas (rainbow background with black lines)
Light Year
a unit of astronomical distance equivalent to the distance that light travels in one year, which is 9.4607 × 1012km (nearly 6 trillion miles).
Astronomical Unit
a unit of measurement equal to 149.6 million kilometers (or 93 million miles), the mean distance from the center of the earth to the center of the sun.
Astronomy
the branch of science which deals with celestial objects, space, and the physical universe as a whole.
Heliocentric
having or representing the sun as the center, as in the accepted astronomical model of the solar system.
Geocentric
having or representing the earth as the center, as in former astronomical systems.
Perihelion
the point nearest to the sun in the path of an orbiting celestial body(such as a planet)
Aphelion
the point in the orbit of a planet, asteroid, or comet at which it is furthest from the sun.
Orbit
the curved path of a celestial object or spacecraft around a star, planet, or moon, especially a periodic elliptical revolution.
Ellipse
a geometric shape (oval) describing the shape of a planets orbit.
Retrograde Motion
the apparent motion of a planet in a direction opposite to that of other bodies within its system
Perigee
the point in the orbit of the moon or a satellite at which it is nearest to the earth.
Apogee
the point in the orbit of the moon or a satellite at which it is furthest from the earth.
Lunar Crater
bowl-shaped depression, or hollowed-out area, produced by the impact of a meteorite
Lunar Mare
large, dark, basaltic plains on Earth’s Moon, formed by ancient volcanic eruptions. They were dubbed maria, Latin for ‘seas’, by early astronomers who mistook them for actual seas.
Lunar Highlands
the lighter, heavily cratered regions of the Moon
Lunar Eclipse
an eclipse in which the moon appears darkened as it passes into the earth’s shadow (during full moon)
solar Eclipse
an eclipse in which the sun is obscured by the moon (during new moon)
Spring Tide
highest tidal range that occurs due to the alignment of Earth, the Moon, & the Sun
Neap Tide
lowest tidal range that occurs near the 1st & 3rd Quarter phases of the Moon
Solstice
the time or date (twice each year) at which the sun reaches its maximum or minimum declination, marked by the longest and shortest days (about June 21 and December 21).
Equinox
the time or date (twice each year) at which the sun crosses the celestial equator, when day and night are of approximately equal length (about September 21 and March 21).
Vernal Equinox (date)
March Twenty-First
Autumnal Equinox (date)
September Twenty-First
Winter Solstice (date)
December Twenty-First
Summer Solstice (date)
June Twenty-First
