Welcome to Bodhiclasses – your trusted companion in holistic and joyful learning. At Bodhiclasses, we believe in nurturing curiosity through simple, relatable explanations rooted in real-world observations. Whether you’re a student, parent, or educator, our aim is to make science not just understandable, but truly enjoyable. This fascinating chapter explores the dynamic relationships and movements of three celestial bodies – the Earth, Moon, and the Sun – and how they affect our daily lives in the form of day and night, seasons, and eclipses.
🌅 1. Rotation of the Earth: Why Do We Have Day and Night?
The chapter begins with a simple observation: shadows change throughout the day. This leads into the concept of Earth’s rotation – the spinning of the Earth on its axis from West to East once every 24 hours. This rotation causes the Sun to appear to move across the sky, rising in the East and setting in the West, even though it’s the Earth that moves.
- A globe and a torch experiment (Page 4) demonstrates how half the Earth faces sunlight (day) while the other half remains in darkness (night).
- Activities help students visualise this using a merry-go-round analogy and real-life shadows, just like Rashmika in the introduction.
🌌 2. Revolution of the Earth: Changing Night Sky and Seasons
Along with rotation, the Earth also revolves around the Sun in a nearly circular orbit, completing one revolution every 365 days and 6 hours.
🛸 2.1 Changing Stars in the Night Sky
Due to this revolution, different stars and constellations become visible at night during different months. The Big Dipper (Saptarishi) appears to move around the Pole Star, and this slow shift is due to the Earth’s changing position in orbit.
☀️ 2.2 Seasons and the Tilted Axis
Seasons occur because the Earth’s axis is tilted, not straight up. This tilt causes:
- Longer days and more intense sunlight in the hemisphere tilted toward the Sun (summer)
- Shorter days and less sunlight in the tilted-away hemisphere (winter)
A great visual on Page 9-10 (Figures 12.9 to 12.11) illustrates how sunlight falls differently on Earth during June and December, explaining solstices and equinoxes:
- Summer Solstice (21 June) – Longest day in Northern Hemisphere
- Winter Solstice (22 December) – Shortest day
- Equinoxes (21 March & 23 September) – Equal day and night
🌑 3. Eclipses: When Shadows Play Cosmic Games
The chapter beautifully explains the concept of eclipses using both activities and diagrams.
🌞 3.1 Solar Eclipse
Occurs when the Moon comes between the Earth and the Sun, blocking sunlight. Despite its smaller size, the Moon can cover the Sun due to its closeness to Earth.
- Total Solar Eclipse: Full Sun is blocked (darkness during the day!)
- Partial Solar Eclipse: Only a part of the Sun is covered
💡 Activity on Page 12 uses your thumb to mimic how a small nearby object (Moon) can block a distant large object (Sun).
⚠️ Important Safety Note: Never view solar eclipses with the naked eye. Use proper filters or attend organised viewings.
🌕 3.2 Lunar Eclipse
Occurs when the Earth comes between the Sun and the Moon, and the Earth’s shadow falls on the Moon. The Moon can appear dark red during a total lunar eclipse. These are safe to observe with the naked eye.
🛰️ Scientific and Cultural Highlights
- Ancient Indian astronomers like Aryabhata understood Earth’s rotation and explained it using poetic verses.
- Tools like the Foucault pendulum and apps like Stellarium help visualise celestial movements.
- Cultural references include traditional knowledge from the Bhil and Pawara communities and the Surya Siddhanta, an ancient text that predicted eclipses accurately.
🌟 In a Nutshell
- Earth rotates (day-night) and revolves (seasons).
- Tilt of Earth’s axis + spherical shape = seasons.
- Solar eclipses = Moon blocks Sun.
- Lunar eclipses = Earth blocks sunlight from Moon.
- Apparent motion of stars, Sun, and Moon is due to Earth’s rotation.
This chapter beautifully blends observation, imagination, and scientific inquiry, inviting young minds to look at the sky with wonder, yet think with reason.
