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17 terms

Astronomy Key Terms

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astronomy
the study of all physical objects beyond Earth.
calendar
a system for organizing time. most calendars organize time within a single unit called a year.
year
is the time required for the Earth to revolute the sun once.
month
roughly the amount of time required for the Moon to orbit/revolute the Earth once.
day
the time required for the Earth to rotate once on its axis.
leap year
a year in which an extra day is added to the calendar
constellation
a section of the sky that contains a recognizable star pattern
altitude
in astronomy, the angle between an object in the sky and the horizon
zenith
an imaginary point in the sky direction above an observer on Earth
horizon
the line at which the sky and Earth appear to meet
light-year
a unit of length equal to the distance that light travels through space in 1 year.
Solar System
Is composed of the sun (a star) and the planets and other bodies that travel around thee sun.
Nebula
dust and gas clumb together in huge intersellar clouds are so big that light takes many years to cross them.
Solar Nebula
the name of the nebula that formed into our solar system.
Planetesimal
when bits of dust within the solar nebula stuck together when the collided, forming the tiny building blocks of the planets.
rotation
The spinning motion of a body on it's axis
Orbit
The elliptical path a body takes as it travels around another body In space