Class 8 Science - Chapter 11 Practice Test

Illumination: The Moon shines because it reflects sunlight. The half of the Moon facing the Sun is illuminated, and the other half is dark.
Phases: As the Moon revolves around Earth, we see different fractions of its illuminated portion. This causes the phases of the Moon.
Waxing and Waning: The period when the bright part increases is the waxing period (Shukla Paksha). The period when it decreases is the waning period (Krishna Paksha).
Key Phases: Full Moon (Purnima), New Moon (Amavasya), Crescent (less than half illuminated), and Gibbous (more than half illuminated).

Solar Day: The average time the Sun takes to go from its highest position in the sky on one day to the highest position the next day (24 hours). Measured using the shortest shadow of a stick.
Solar Calendars: Based on the Earth's revolution around the Sun (approx. 365 1/4 days). To adjust for the extra quarter day, an extra day is added every four years (Leap Year). Example: Gregorian Calendar.
Lunar Calendars: Based on the Moon's phases. 12 lunar months equal about 354 days, which falls short of the solar year by about 11 days.
Luni-solar Calendars: Follow the Moon's phases but add an extra month (Adhika Maasa / Intercalary month) every few years to stay synced with the solar year and seasons.

It is a solar calendar with 365 days, starting on 22 March (the day after the spring equinox).
The first month is Chaitra. During leap years, a day is added to Chaitra, and the year begins on 21 March.

Man-made objects that orbit the Earth, usually around 800 km above the surface.
Uses: Communication, navigation, weather monitoring, disaster management, and scientific research.
ISRO Missions: Cartosat (mapping), AstroSat (scientific observations of stars), Chandrayaan (Moon), Aditya L1 (Sun).

🌌 Chapter 11 Revision Notes