Meridian – a half circle extending from your horizon (altitude 0) due south through your zenith to your horizon due north. Zenith – the point directly overhead, which has an altitude of 90 degrees. Latitude –The angular north-south distance between Earth’s equator and a location on Earth’s surface. Longitude – The angular east-west distance between the prime meridian (which passes through Greenwich) and a location on Earth’s surface. Speed – The rate at which an object moves. Its units are distance divided by time, such as m/s or km/hr. Velocity – The combination of speed and direction of motion; it can be stated as a speed in a particular direction, such as 100 km/hr due north. Force – Anything that can cause a change in momentum.

Momentum – The product of an object’s mass and velocity. Acceleration – The rate at which an object’s velocity changes. Its standard units are m/s squared. Kinetic energy - Energy in motion, given by the formula (1/2)m * v squared. Gravitational potential energy - Energy that an object has by virtue of its position in a gravitational field; an object has more gravitational potential energy when it has a greater distance that it can potentially fall. Power – The rate of energy usage, usually measured in watts (1 watt = 1 joule/s). Wavelength - The distance between adjacent peaks (or troughs) of a wave. Frequency – The rate at which peaks of a wace pass by a point, measured in units of 1/s often called cycles per second or hertz. Redshift – (Doppler) A Doppler shift in which spectral features are shirted to longer wavelengths, observed when an object is moving away from the observer. Focal plane – The place where an image created by a lens or mirror is in focus. Light pollution – Human made light that hinders astronomical observations. Terrestrial planet - Rocky planets similar in overall composition to Earth. Jovian planet – Giant gaseous planets similar in overall...

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