Question 1

Why does the Moon have phases?

Accepted Answer

The Moon's phases are caused by its orbit around Earth relative to sunlight. The Sun always illuminates half of the lunar sphere, but as the Moon orbits Earth every 29.5 days, observers on Earth see varying fractions of that sunlit hemisphere — creating the 8 phases from New Moon to Full Moon.

Question 2

What causes Earth's seasons?

Accepted Answer

Seasons are caused by Earth's 23.44° axial tilt relative to its orbital plane around the Sun, not by distance variations. Because the tilt remains fixed in space, each hemisphere alternately tilts toward the Sun (experiencing summer with longer days and direct sunlight) and away from the Sun (experiencing winter with shorter days and spread-out sunlight).

Question 3

How does the Sun's altitude change with latitude and season?

Accepted Answer

The Sun's noon altitude in the sky depends on the observer's latitude and Earth's orbital position. At the equator, day length remains near 12 hours year-round and the Sun passes near the zenith. At higher latitudes, the Sun's path shifts lower in winter and higher in summer, producing dramatic changes in day length and solar heating.

Question 4

Are Pupil simulations free for classrooms and students?

Accepted Answer

Yes. Pupil simulations are 100% free, require no account or sign-up, contain no ads or telemetry, and run directly in any web browser with offline PWA support and automatic 2D fallbacks for school Chromebooks.