Science Galaxy Flashcards
Orbit
the circular path of an object as it revolves around another object
Solar system
a system of objects that revolve around a star
galaxy
a group of solar systems, dust, and gas held together by gravity; our solar system is part of the Milky Way galaxy
universe
everything that exists in, on and around the Earth
Satellite
a natural or artificial object that revolves around another object in space
Impact crater
a large, circular pit in the surface of a planet or other body in space usually formed when two bodies in space collide
rotation
the spinning of a celestial body, such as a planet, around an axis
revolution
the orbiting of an object around another object
season
a period of the year determined by the position of Earth as it revolves around the sun
equinox
he twice-a-year occurrence during which Earth’s axis is perpendicular (at a 90 angle) to a line joining the Sun and Earth’s center
Solstice
the twice-a-year occurrence during which the Sun appears at the highest point in the sky as seen from the North or South pole
Mare
a large, level basalt plain on the surface of the moon, appearing dark by contrast with highland areas.
eclipse
an event whereby one astronomical body passes between two other astronomical bodies
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
Astronomical unit
the mean distance from the center of the Earth to the center of the sun (about 149.6 million kilometers); used to measure distances in the solar system
Ellipse
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
DescriptionA terrestrial planet, telluric planet, or rocky planet is a planet that is composed primarily of silicate rocks or metals. Within the Solar System, the terrestrial planets are the inner planets closest to the Sun, i.e. Mercury, Venus, Earth, and Mars.
Gas giant
A gas giant is a giant planet composed mainly of hydrogen and helium. Gas giants are sometimes known as failed stars because they contain the same basic elements as a star. Jupiter and Saturn are the gas giants of the Solar System.
Asteroid
a small object made of rock or metal that orbits the sun
Comet
a body of ice and dust that travels in a long narrow orbit around the sun
Meteor
a streak of light in the sky that forms when a piece of rock from space burns up in Earth’s atmosphere (related term: shooting star)
Meteorite
a piece of rock or metal from space that strikes Earth’s surface
geocentric
having the Earth as the center