Chapter 3&4: Moon Phases and Eclipses/History

Moon Phases

The changes in the Moon’s appearance as seen from Earth, caused by the Moon’s orbit and the Sun lighting different parts of it.

The Moon’s Orbital Motion

From Earth, we see different portions of the Moon’s surface lit by the Sun, causing the phases of the Moon

The Lunar Phase Cycle

We always see the same side of the Moon facing Earth

Sidereal Period - 27.3 days

The Moon has to go all the way around the Earth and return to that same "finish line" of stars.

Synodic Period - 29.5 days

Moon goes from one New Moon to Full Moon to the next New Moon because of how the Moon, Earth, and Sun line up

1)New Moon

2)Waxing Crescent

3)First Quarter

4)Waxing Gibbous

The Waxing(growing bigger) Phases of the Moon

1)invisible moon - can’t see anything

2)a tiny slice of light - Moon is smiling just a little

3)a "half pizza" of light.

4)almost full, but not quite

1)Full Moon

2)Waning Gibbous

3)Last Quarter

4)Waning Crescent

The Waning Phases of the Moon

1)Entire lit side is visible.

2)Light decreases; more than half is still lit.

3)Opposite half of the lit side is visible.

4)Small part of the lit side remains before the cycle restarts

Truth: Every part of the Moon gets sunlight for two weeks as it rotates

Myth: The Moon has a “dark side” that’s never lit.

Truth: Studies show no connection between human behavior and the Moon.

Myth: People act differently during a Full Moon.

Lunar Eclipses

Earth’s shadow falls on the Moon when Earth is between the Sun and Moon.

Umbra

The region of total shadow

Penumbra

The region of partial shadow with dimming

Total Lunar Eclipse(1 or 2 times per y): only during Full Moon

The Moon is entirely in Earth’s umbra. Appears reddish due to sunlight scattered by Earth’s atmosphere.

Penumbral Lunar Eclipse

Moon only enters the penumbra, dimmed

Solar Eclipse: only during New Moon

The Moon’s shadow falls on Earth when the Moon is between Earth and the Sun.

Total Solar Eclipse

The Moon completely blocks the Sun.

Annular Solar Eclipse

The Moon appears smaller and doesn’t fully cover the Sun, leaving a "ring of fire."

Prominences

Feature of the Solar Eclipse - Bright loops of gas around the Sun during a total eclipse

Saros Cycle

Predicting Eclipses: A pattern of eclipses repeating every 18 years, 11 days, and 8 hours.

the Universe was divided into two parts: Earth and Heavens(perfect & unchangeable)

Aristotle believed

a universe where all objects in the sky sit on moving spheres, with the Earth at the centre

geocentric model

Earth and planets orbit around the Sun at the center of the universe - The Copernican Revolution

heliocentric model

each planet's orbit about the Sun is an ellipse

Kepler’s First Law of Planetary Motion

Planets move faster when they are closer to the Sun and slower when they are farther away.

Планета как будто рисует треугольники своей орбитой, и за равные промежутки времени площадь этих треугольников всегда остается одинаковой, даже если их форма меняется

Kepler’s Second Law of Planetary Motion

The farther a planet is from the Sun, the longer it takes to complete one orbit.

T^{^}2∝r^3 where T is the time (orbital period) and r is the distance from the Sun.

Kepler’s Third Law of Planetary Motion

Truth: Galileo was condemned for disobeying 1616 orders to “not to hold, teach, or defend in any way” the principles of Copernicus

Misconception: Galileo was condemned by the Inquisition for believing that Earth moves around the Sun

Galilean Moons orbiting Jupiter (now called Io, Europa, Ganymede, and Callisto)

Galileo’s Telescopic Observations (1609-1610):

Conclusion: Not everything orbits Earth — strong evidence in favor of Copernicus' heliocentric model.

observer's latitude on Earth

This means the North Celestial Pole appears (70° - dif. degrees) above the northern horizon at this latitude.

angular distance from the northern horizon to the North Celestial Pole (NCP) is equal to