Download Solar day and sidereal day …

Solar day and sidereal day …
Based on an idea by Cyril Mustière (maths teacher at the Collège Paule Berthelot in Mana)
Aimed at schoolchildren: from middle school and up.
Instructions: To understand the difference between a solar day (one day on Earth in relation
to the Sun) and a sidereal day (one day on Earth in relation to a distant star), reproduce the
following scene. One volunteer symbolises a star, another the Sun and a third the Earth. To
begin with, the Earth faces the Sun and the distant star, then the pupil representing the Earth
begins to rotate around the Sun while turning on his own axis. As soon as his field of view is
again facing the distant star he stops: a sidereal day has just taken place. He continues his
route and as soon as his field of view is facing the Sun he stops again: a solar day has just
been completed. Which is longer, the solar day or the sidereal day?
Info +: In 24 hours the Earth-Sun direction changes by about 1°. For a given point on Earth
to face the Sun again, it therefore needs to rotate by 361°. This is why the solar day lasts four
minutes longer than the sidereal day.