Video Notes Review: Astronomy Basics (Ecliptic, Moon Phases, Eclipses, and Early Theories)

Flashcards covering key concepts from Page 1 and Page 2 notes: ecliptic, Sun patterns, seasonal markers, stars, planets, Moon phases, eclipses, and early astronomical theories.

What is the ecliptic?

The Sun’s apparent annual path through the sky, defined by the plane of Earth’s orbit on which the Sun seems to travel against the background stars.

What is defined by a zodiac constellation?

The Sun’s apparent path across the sky (the ecliptic) is defined by the zodiacal constellations it passes through.

Where do planets lie in relation to the ecliptic?

Planets lie near the ecliptic plane; their orbits are roughly in the same plane as Earth’s orbit.

How does the Sun move across the sky and where does it set?

The Sun arcs from east to west and sets in the western horizon.

Why does the Sun appear lower in winter?

Because of the tilt of the Earth's axis relative to its orbit around the Sun.

What is the Summer Solstice?

The day with the longest daylight; Sun at its northernmost position in the sky (in the Northern Hemisphere).

What is the Winter Solstice?

The day with the shortest daylight; Sun at its southernmost position in the sky (in the Northern Hemisphere).

What is the Vernal (Spring) Equinox?

The moment when the Sun crosses the celestial equator moving northward, marking spring.

What is the Autumnal (Fall) Equinox?

The moment when the Sun crosses the celestial equator moving southward, marking autumn.

Do stars go east to west?

Yes; stars appear to move from east to west across the sky.

How do stars rise each day according to the notes?

Stars rise about 15 minutes earlier each day.

What is the origin of the word 'planet'?

From the word planete meaning wanderer.

What is retrograde motion?

Backward motion of a planet relative to the background stars.

What is prograde motion?

Forward motion of a planet relative to the background stars.

Name the main Moon phases listed.

Full, New, Crescent, and Gibbous.

What are the two main categories of eclipses?

Lunar eclipses and Solar eclipses.

What is a total lunar eclipse?

The Moon passes completely through Earth’s umbra.

What is a partial solar eclipse?

Only part of the Sun is obscured by the Moon (through the penumbra).

What is an annular eclipse?

Moon is near apogee and cannot fully cover the Sun, leaving a ring of sunlight (annulus).

What are the shadows involved in eclipses?

Umbra (dark central shadow) and Penumbra (lighter outer shadow).

When do solar eclipses occur in relation to the Moon phase?

Around New Moon.

What is Polaris?

The North Star, located near the north celestial pole.

What is the Zenith?

The highest point in the sky directly overhead.

What does the angle to Polaris represent?

Your latitude.

What is Right Ascension?

Celestial longitude measured in hours, minutes, and seconds.

What is Declination?

Celestial latitude measured in degrees.

What is an equinox?

The moment when the ecliptic meets the celestial equator.

Who proposed epicycles in astronomy?

Ptolemy.

What does geocentric mean and who supported it?

Earth-centered; supported by Aristotle, based on the idea of no observable parallax.

Who proposed the heliocentric model and what did it show?

Copernicus; the model showed Earth is not at the center of the universe.

What evidence did Galileo provide for heliocentrism?

Venus shows phases similar to the Moon, supporting a Sun-centered system.

Who measured Earth’s size using a well and shadows from a distance between Syene and Alexandria?

Eratosthenes.