The study of the sky, the science behind celestial phenomena and cosmic objects, and the exploration of the origins of the universe you inhabit
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Planet
It comes from the ancient Greek word planetes, meaning "wanderer."
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International Astronomical Union
It governs science and establishes constellation boundaries so that astronomers can agree on which stars belong to which constellation
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Hydra
The largest constellation; the Water Snake
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Crux
The smallest constellation; the Cross
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Serpens
The Serpent
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Magnitude
It is a measure of a stars brightness
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Light Years
The distances to the stars and other objects beyond the planets of our solar system
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RA
The position of a star measured in the east-west direction in the sky
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Dec
The position of the star measured in the north-south direction on the sky
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North Celestial Pole (NCP)
The place to which the axis of Earth points in the north direction
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South Celestial Pole (SCP)
The place to which the axis of Earth points in the south direction
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**Ophiuchus**
the Serpent Bearer
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**Greek letter**
Either by ancient Greek astronomers or by astronomers of later civilizations, the brighter stars in a constellation were given a **_____**.
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**proximity**
Individual stars in a constellation often have no relationship to one another other than their **____** in the sky as seen from Earth.
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**semi circles**
The imaginary lines of equal RA run through the NCP and SCP as **____** centered on the center of Earth.
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**Professional astronomers**
* They carry out their astronomical work by using telescopes to observe the stars' visible light or by listening for radio waves that travel to the stars. * They research the Sun, the solar system, the Milky Way, and the cosmos beyond.
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**Asterism**
* **Star pattern that’s not identical to one of the 88 recognized constellations.** * It might only contain stars from one constellation, or it might contain stars from several different constellations.
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**Amateur astronomers**
* When observing the sky with their naked eyes, binoculars, and telescopes, they typically know the constellations and use them as compass points. * They crisscross the Earth to take pictures of the shadows cast by asteroids passing in front of bright stars, track the brightness of variable stars, find asteroids, comets, and exploding stars. * They even contribute to professional research projects using their smartphones and home computers.
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**88**
Astronomers have divided the sky into **____ constellations**, which contain all the stars you can see.