Eclipses

Introduction to Eclipses

• Learning Objectives: Understand causes, characteristics, and differences between solar and lunar eclipses.
• Do Now Question: How do eclipses relate to light?

Outcomes of Learning

• Can describe phenomena of both solar and lunar eclipses.
• Can differentiate between solar and lunar eclipses.
• Can explain geographical impact: why solar eclipses are local vs. lunar eclipses are global.
• Understand the reason behind the red color of a lunar eclipse.

Historical Context of Eclipses

• Ancient accounts remark upon eclipses with awe, such as:
  • Archilochus (680–645 BCE): Described day turning suddenly into night.
  • Herodotus (5th century BCE): Noted a solar eclipse ending a battle, emphasizing its impact on ancient cultures.

Types of Eclipses

Solar Eclipse

• Definition: Occurs when the Moon passes between the Sun and Earth, blocking sunlight.
• Visibility: Only a small area of Earth experiences the eclipse.
• Types:
  • Partial Solar Eclipse: Only part of the Sun is obscured by the Moon.
  • Total Solar Eclipse: The Sun is completely covered by the Moon.

Characteristics of a Solar Eclipse

• Umbra: The area of complete shadow where total visibility occurs.
• Penumbra: The area of partial shadow; a partial eclipse can be seen here.
• Mechanism: Occurs when the Moon is directly aligned between the Sun and Earth.

Lunar Eclipse

• Definition: Happens when Earth passes between the Sun and Moon, casting a shadow on the Moon.
• Visibility: Often visible from anywhere on the night side of Earth.
• Types: Can be referred to as a 'Blood Moon' during totality due to the red color that appears.

Characteristics of a Lunar Eclipse

• Umbra: The area of total shadow making the Moon appear red.
• Penumbra: The region of partial shadow; a part of the Moon may appear only slightly shaded.
• Mechanism: The Moon must be on the opposite side of Earth from the Sun to create this phenomenon.

Reasons for Color in Lunar Eclipses

• Red Hue: The Moon appears red during a lunar eclipse due to Rayleigh scattering, similar to how sunsets appear red. During the eclipse, sunlight is bent (refracted) through Earth's atmosphere, filtering out blues and allowing reds to reach the Moon.

Diagrams and Visuals

• Understanding Diagrams: Label diagrams illustrating solar and lunar eclipses. Important to visualize the positions of the Sun, Moon, and Earth during each type of eclipse.
• Include details such as the umbra and penumbra in both diagrams.

True/False Assessment

• True Statements:
  • A lunar eclipse can only occur at night.
  • The Earth is larger than the Moon.
  • The Moon appearing red is not due to reflection but atmospheric refraction.
• False Statements:
  • In a solar eclipse, the Earth comes between the Sun and the Moon.
  • A solar eclipse blocks the entirety of the Earth.

Conclusion and Review

• Summarize understanding: What was known about eclipses before, new knowledge gained, and remaining questions.
• Through engaging discussions and assessment tasks, reinforce the learning of celestial phenomena and their effects on ancient and modern societies.