Podcast
Questions and Answers
The point in the sky directly above your head at any given time is called the ___
The point in the sky directly above your head at any given time is called the ___
zenith
The celestial sphere turns once around each day because ______.
The celestial sphere turns once around each day because ______.
the planet is rotating
The south celestial pole and the north celestial pole lie in the sky directly above the _____.
The south celestial pole and the north celestial pole lie in the sky directly above the _____.
Earth's axis
Halfway between the celestial poles lies the _____.
Halfway between the celestial poles lies the _____.
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In the Northern Hemisphere, the altitude (height in degrees above the horizon) of the North Star is always roughly equal to the ____.
In the Northern Hemisphere, the altitude (height in degrees above the horizon) of the North Star is always roughly equal to the ____.
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The star that is currently closest to the North Celestial Pole is ______.
The star that is currently closest to the North Celestial Pole is ______.
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As seen from the continental United States, the Big and Little Dipper _____.
As seen from the continental United States, the Big and Little Dipper _____.
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Where on Earth do stars always circle the zenith (and never rise and set)?
Where on Earth do stars always circle the zenith (and never rise and set)?
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From horizon to opposite horizon, the sky takes up how much angular distance?
From horizon to opposite horizon, the sky takes up how much angular distance?
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The Sun's apparent path around the celestial sphere is called _____.
The Sun's apparent path around the celestial sphere is called _____.
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If the Earth goes around the Sun, why is the ecliptic not lined up with the celestial equator?
If the Earth goes around the Sun, why is the ecliptic not lined up with the celestial equator?
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Every celestial object appears to go around the Earth once a day. In addition to this motion, which celestial object has the fastest apparent motion in the sky?
Every celestial object appears to go around the Earth once a day. In addition to this motion, which celestial object has the fastest apparent motion in the sky?
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The strip of the sky through which the Sun, Moon, and bright planets appear to move in the course of a year is called ____.
The strip of the sky through which the Sun, Moon, and bright planets appear to move in the course of a year is called ____.
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The 88 sectors into which astronomers today divide the celestial sphere (the whole sky) are called ______.
The 88 sectors into which astronomers today divide the celestial sphere (the whole sky) are called ______.
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Which ancient Greek thinker suggested (long before Copernicus) that the Earth is moving around the Sun?
Which ancient Greek thinker suggested (long before Copernicus) that the Earth is moving around the Sun?
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How did Eratosthenes measure the size of the Earth?
How did Eratosthenes measure the size of the Earth?
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When a planet temporarily moves westward in the sky over the course of several weeks or months (instead of eastward, as it typically does), we call it _____.
When a planet temporarily moves westward in the sky over the course of several weeks or months (instead of eastward, as it typically does), we call it _____.
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The slow tipping of the Earth's axis in a circle with a period of about 26,000 years is called_______.
The slow tipping of the Earth's axis in a circle with a period of about 26,000 years is called_______.
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The great astronomer of ancient times who summarized and improved a system of circles upon circles to explain the complicated motions of the planets (and published the system in a book now called The Almagest) is: ______.
The great astronomer of ancient times who summarized and improved a system of circles upon circles to explain the complicated motions of the planets (and published the system in a book now called The Almagest) is: ______.
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In Ptolemy's system, how did the planets explain the retrograde motion of planets like Jupiter?
In Ptolemy's system, how did the planets explain the retrograde motion of planets like Jupiter?
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Study Notes
Celestial Concepts
- The zenith is the point directly above an observer's head in the sky.
- The celestial sphere rotates daily due to Earth's rotation.
- North and south celestial poles align with Earth's axis.
- The celestial equator lies halfway between the celestial poles.
Observational Astronomy
- In the Northern Hemisphere, the altitude of the North Star (Polaris) equals the latitude of the observer.
- Big and Little Dipper constellations are circumpolar in the northern sky throughout the year.
- At the North Pole, stars circle the zenith, never rising or setting.
Angular Measurements
- The sky from horizon to horizon spans an angular distance of 180 degrees.
- The ecliptic is the Sun's apparent path across the celestial sphere.
Celestial Mechanics
- The ecliptic does not align with the celestial equator due to Earth's axial tilt.
- The Moon exhibits the fastest apparent motion among celestial objects, completing its journey across the sky daily.
- The zodiac is the band of the sky where the Sun, Moon, and bright planets appear to move annually.
Constellation and Historical Figures
- The celestial sphere is divided into 88 constellations by astronomers.
- Aristarchus of Samos proposed the heliocentric model long before Copernicus.
- Eratosthenes calculated Earth's circumference by comparing the Sun's angle at two different latitudes.
Motion Dynamics
- Retrograde motion refers to a planet's apparent westward movement over weeks or months.
- Precession is the gradual change in Earth's axial tilt that occurs over approximately 26,000 years.
Ancient Astronomical Systems
- Ptolemy enhanced a geocentric model that utilized circular orbits to explain planet movements and retrograde motion.
- In Ptolemy’s system, planets are thought to move along small circles (epicycles) while circling near Earth.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Test your knowledge of key astronomy terms and concepts with these flashcards. Each card presents a fundamental idea related to celestial mechanics and the structure of the sky. Ideal for students preparing for an astronomy exam or anyone interested in the field.
