SCIENCE VOCABULARY

GRAVITY

• the force that attracts a body toward the center of the earth, or toward any other physical body having mass.

ORBIT

• the curved path of a celestial object or spacecraft around a star, planet, or moon, especially a periodic elliptical revolution.

ROTATION

• the action of rotating around an axis or center

REVOLUTION

• the movement of an object in a circular or elliptical course around another or about an axis or center.

EARTHS AXIS & TILT

• the Earth's axis is tilted 23.5 degrees from the plane of its orbit around the sun. But this tilt changes. During a cycle that averages about 40,000 years, the tilt of the axis varies between 22.1 and 24.5 degrees.

DAY & NIGHT

SEASONS

• 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.

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.

EQUINOX

• the time or date (twice each year) at which the sun crosses the celestial equator, when day and night are of equal length (about September 22 and March 20).

EARTHS 4 HEMISPHERE

NATURAL SATELLITES

• A natural satellite, or moon, is a celestial body that orbits another body (a planet, dwarf planet, or small Solar System body), which is called its primary, and that is not artificial.

CONSTELLATIONS

• a group of stars forming a recognizable pattern that is traditionally named after its apparent form or identified with a mythological figure. Modern astronomers divide the sky into eighty-eight constellations with defined boundaries.