a small piece of solid matter that enters Earth’s atmosphere and burns up, popularly called a shooting star because it is seen as a small flash of light
an apparent displacement of a nearby star that results from the motion of Earth around the Sun
the largest unit of distance in astronomy, equal to 3.26 light-years; at a distance of 1 parsec, a star has a parallax of 1 arc second
(of a comet) a tail consisting of two parts: the dust tail is made of dust loosened by the sublimation of ice in a comet that is then pushed by photons from the Sun into a curved stream; the ion tail is a stream of ionized particles evaporated from a comet and then swept away from the Sun by the solar wind
either of the two moments in the year when the Sun’s apparent path is farthest north (summer solstice) or south (winter solstice) from Earth’s Equator. Summer Solstice is the longest day of the year and occurs on June 20 or 21, Winter Solstice is the longest night of the year and occurs on December 21 or 22
a portion of a meteor that survives passage through the atmosphere and strikes the ground
a region of space beyond Neptune that is dynamically stable (like the asteroid belt); the source region for most short-period comets
the region of the solar system between the orbits of Mars and Jupiter in which most asteroids are located; the main belt, where the orbits are generally the most stable, extends from 2.2 to 3.3 AU from the Sun
is the revolving of one object around another in an oval-shaped path called an ellipse
an eclipse of the Sun by the Moon, caused by the passage of the Moon in front of the Sun; solar eclipses can occur only at the time of the new moon
alternate rising and falling of sea level caused by the difference in the strength of the Moon’s gravitational pull on different parts of Earth
the distance light travels in 1 year, equal to 5,865,696,000,000 miles
the path of an object that is in revolution about another object or point
a stony or metallic object orbiting the Sun that is smaller than a major planet but that shows no evidence of an atmosphere or of other types of activity associated with comets
a natural satellite that revolves around a planet and does not generate its own light