Planet Vocabulary Flashcards
Orbit
the curved path of a celestial object or spacecraft around a star, planet, or moon, especially a periodic elliptical revolution.
Solar system
the collection of eight planets and their moons in orbit around the sun, together with smaller bodies in the form of asteroids, meteoroids, and comets.
Galaxy
a system of millions or billions of stars, together with gas and dust, held together by gravitational attraction.
Universe
all existing matter and space considered as a whole; the cosmos. The universe is believed to be at least 10 billion light years in diameter and contains a vast number of galaxies; it has been expanding since its creation in the Big Bang about 13 billion years ago.
Satellite
an artificial body placed in orbit around the earth or moon or another planet in order to collect information or for communication
Impact crater
a crater on a planet or moon caused by the impact of a meteorite or other object, typically circular with a raised rim.
Rotation
the action of rotating around an axis or center.
Revolution
a forcible overthrow of a government or social order, in favor of a new system.
Season
each of the four divisions of the year (spring, summer, autumn, and winter) marked by particular weather patterns and daylight hours, resulting from the earth’s changing position with regard to the sun.
Equinox
the time or date (twice each year) at which the sun crosses the celestial equator, when day and night are of equal length
Solstice
either of the two times in the year, the summer solstice and the winter solstice, when the sun reaches its highest or lowest point in the sky at noon, marked by the longest and shortest days.
Mare
the female of a horse or other equine animal.
Eclipse
a great circle on the celestial sphere representing the sun’s apparent path during the year, so called because lunar and solar eclipses can occur only when the moon crosses it.
Umbra
the fully shaded inner region of a shadow cast by an opaque object, especially the area on the earth or moon experiencing the total phase of an eclipse.
Penumbra
the partially shaded outer region of the shadow cast by an opaque object.
Astronomy unit
a unit of measurement equal to 149.6 million kilometers, the mean distance from the center of the earth to the center of the sun.
Ellipsis
a regular oval shape, traced by a point moving in a plane so that the sum of its distances from two other points (the foci) is constant, or resulting when a cone is cut by an oblique plane which does not intersect the base.
Terrestrial planet
Within the Solar System, the terrestrial planets are the inner planets closest to the Sun, i.e. Mercury, Venus, Earth, and Mars. The terms “terrestrial planet” and “telluric planet” are derived from Latin words for Earth, as these planets are, in terms of structure, “Earth-like”.
Gas giant
a large planet of relatively low density consisting predominantly of hydrogen and helium, such as Jupiter, Saturn, Uranus, or Neptune.
Asteroid
a small rocky body orbiting the sun. Large numbers of these, ranging in size from nearly 600 miles
Comet
a celestial object consisting of a nucleus of ice and dust and, when near the sun, a “tail” of gas and dust particles pointing away from the sun.
Meteor
a small body of matter from outer space that enters the earth’s atmosphere, becoming incandescent as a result of friction and appearing as a streak of light.
Meteorite
a meteor that survives its passage through the earth’s atmosphere such that part of it strikes the ground. More than 90 percent of meteorites are of rock, while the remainder consist wholly or partly of iron and nickel.
Geocentric
having or representing the earth as the center, as in former astronomical systems.
Heliocentric
having or representing the sun as the center, as in the accepted astronomical model of the solar system.
Gravity
the force that attracts a body toward the center of the earth, or toward any other physical body having mass
Tide
the alternate rising and falling of the sea, usually twice in each lunar day at a particular place, due to the attraction of the moon and sun.
Waxing
the process of removing unwanted hair from a part of the body by applying wax and peeling off the wax and hairs together.
Gibbous moon
The definition of gibbous refers to a moon in between a half-moon but less than a full moon, or something that protrudes or creates an obvious bulge.
Crescent moon
A crescent is a thin, curved shape that’s thicker in the middle and tapers to thin points at each end, like the little sliver of moon you might notice in the sky.
Full moon
the phase of the moon in which its whole disk is illuminated.
