Astronomy Terms and Definitions

Arcsecond ("))

• A unit of angular measurement equal to 1/60 of an arcminute

• A unit of linear measurement equal to 1/60 of a meter

• A unit of time measurement equal to 1/60 of a second

• A unit of temperature measurement equal to 1/60 of a degree

Parallax

• A technique used to determine the distance of nearby stars by observing their "shift" in position based on background stars

• A method for measuring the brightness of distant galaxies

• A process for calculating the age of stars based on their color

• A technique for identifying exoplanets by observing their gravitational effects

Solar Luminosity (L☉)

• A unit of luminosity equal to the Sun (1 L☉ = 3.828 × 10^{26} W)

• A measure of the brightness of a star compared to the Sun

• A unit of energy emitted by a star per second

• A measure of the distance from the Earth to the Sun

Light-Year (ly)

• The distance light travels in one year (9.46 \times 10^{12} km or 9,460,000,000,000 km)

• The distance light travels in one month (2.52 \times 10^{11} km)

• The distance light travels in one day (2.59 \times 10^{10} km)

• The distance light travels in one hour (1.08 \times 10^{9} km)

Apparent Magnitude

• The brightness of a celestial object as seen from Earth

• The distance of a celestial object from Earth

• The size of a celestial object

• The temperature of a celestial object

Cosmic Calendar

• A method to visualize the solar system's formation

• A method to reasonably visualize and comprehend the chronology of the universe's 14 billion year history

• A calendar used by ancient civilizations to track lunar cycles

• A timeline of significant events in human history

What is an Astronomical Unit (AU)?

• The average distance between the Earth and the Sun

• The distance light travels in one year

• The distance from the Earth to the Moon

• The distance between Mars and Jupiter

Arcminute (')

• A unit of angular measurement equal to 1/60 of a degree

• A unit of distance measurement equal to 1/60 of a meter

• A unit of time measurement equal to 1/60 of a second

• A unit of temperature measurement equal to 1/60 of a Celsius degree

Arcsecond (" )

• A

• B

• C

• D

Spectroscopy

• Used to determine the chemical composition of stars

• A method for measuring the speed of light

• A technique for analyzing sound waves

• A process for studying the motion of planets