Test Review Terms Elliptical orbit Rotation Axis Full moon Aphelion Major axis Foci Semimajor axis Perihelion Sun Maunder minimum Solar day Seasons Lunar phases photosphere Fission Fusion Electromagnetic radiation Ecliptic Vernal equinox Solar eclipse Lunar eclipse Summer solstice Autumnal equinox Winter solstice Keplar’s laws Law of universal gravitation precession

sun occupies one focus of the ellipse, not the center. The other focus is empty. An ellipse is “almost” a circle, so the universe is geometric although not perfect. The formula used to determine the shape of the ellipse is e=d/l where eccentricity is equal to the distance between the foci divided by the length of the major axis Keplers 1 st Law – law of Ellipses

Spring day characterized by day and night of equal lengths Vernal equinox

Plane of the Earth’s orbit about the sun ecliptic

equation that validates his second law. equation that validates his second law. P 2 = a 3 Keplers 3 rd Law

Earth’s position around December 21st, at which the northern hemisphere has its minimum daylight hours Winter solstice

Periods of low sunspot activity Maunder minimum

Imaginary line through which the Earth rotates on axis

Phase of the moon in which it appears entirely illuminated Full moon

point that determines the shape of ellipse foci

Half the distance of the major axis Semi major axis

Occurs when the moon passes directly between the sun and earth Solar eclipse

The statement that describes the relationship among the masses of two bodies and the distance between them Law of universal gravitation

Wobble of the Earth’s axis caused by the Moon’s gravitational force on Earth precession

Star closest to our planet sun

Caused by the tilt of the Earth and its orbit around the sun seasons

Passes through the foci of an ellipse Major axis

An imaginary line between the Sun and a planet that sweeps out equal amounts of area in equal amounts of time Kepler’s Second Law

Point in Earth’s revolution around the sun at which it is furthest aphelion

Electric and magnetic disturbances that travel through space Electromagnetic radiation

24 hours, our time keeping system is based on it. Solar day

Occurs when the moon passes through the earths shadow Lunar eclipse

Orbit that is less than one but greater than 0 in eccentricity Elliptical orbit

Earth’s position around June 21, at which the northern hemisphere has its maximum daylight hours Summer solstice

Point in the Earth’s orbit when closest to the sun perihelion

Sequential changes in the appearance of the moon Lunar phases

Earth spining on its axis in a 24 hour cycle rotation

High energy required, fusing of 2 or more lighter atoms into a larger 1, produces radiant energy of stars, hydrogen bomb fusion

Splitting of a large atom into two or more smaller ones, takes little energy, produces many highly radioactive particles, atomic bomb fission

Emits most of the light from the sun photosphere

Fall day characterized by day and night of equal lengths Autumnal equinox