Astronomy and Earth Science Terms

Apogee

• The point in the orbit of the moon or a satellite at which it is furthest from the earth.

• The point in the orbit of the moon or a satellite at which it is closest to the earth.

• The point at which a satellite enters the atmosphere.

• The point in the orbit of a planet where it is farthest from the sun.

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.

• 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.

• A type of lunar eclipse that occurs when the earth is directly between the sun and the moon.

• The area of light surrounding a shadow that is illuminated by direct sunlight.

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.

• 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.

• A period of equal day and night length.

• The time of year when the sun is at its lowest point in the sky.

Foucault Pendulum

• A pendulum that demonstrates the rotation of the Earth by exhibiting an apparent change in its plane of oscillation.

• A device used to measure the speed of light in a vacuum.

• A type of pendulum that swings in a perfect circle without any external forces.

• A pendulum that is used to demonstrate the principles of harmonic motion.

Equinox

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

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

• The time or date when the sun is furthest from the Earth.

• The time or date marking the beginning of summer.

Solar Eclipse

• An event in which the moon passes between the sun and earth, blocking all or part of the sun.

• A phenomenon where the sun completely disappears from the sky.

• A type of lunar event where the earth blocks the sun's light.

• A situation where the moon reflects sunlight towards the earth.

Tides

• 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.

• A type of ocean current that flows in one direction.

• The movement of water caused by wind and weather patterns.

• The process of evaporation and condensation in the water cycle.

Solar Time

• Time measured by the position of the sun in the sky, typically expressed in terms of the hour angle of the sun.

• A method of measuring time based on the average length of a day.

• A timekeeping system that uses atomic clocks for precision.

• A time zone that adjusts for daylight saving time.

Waxing Moon

• The phase of the moon when it is increasing in size, moving from the new moon towards the full moon.

• The phase of the moon when it is increasing in size, moving from the new moon towards the full moon.

• The phase of the moon when it is completely dark and not visible from Earth.

• The phase of the moon when it is fully illuminated and appears as a circle.

Lunar Eclipse

• An event in which the earth passes between the sun and the moon, and the earth's shadow falls on the moon.

• A phenomenon where the moon passes between the earth and the sun, blocking sunlight from reaching the earth.

• A situation where the earth's shadow falls on the sun, causing a solar eclipse.

• An occurrence when the moon is fully illuminated by the sun's light.