Transcript Seasons

Seasons and the Angle of Solar Radiation
Rotation: the time it takes a planet to rotate (spin) once
on its axis. For Earth = 1 day
Revolution: the time it takes a planet to go once around the
Sun. For Earth = 1 year
One year is divided into four seasons; spring, summer,
fall, and winter
Spring starts on the vernal equinox ~ March 21
Summer starts on the summer solstice ~ June 21
Fall starts on the autumnal equinox ~ September 22
Winter starts on the winter solstice ~ December 21
Solstice is when the Sun rises or sets as far North or
South of the equator as it can (days are longest or
Equinox is when the Sun crosses the equator, so the
days and nights are equal in time
Sun Setting: Nov. 18
Jun. 15
Billions of years ago, before there was life on Earth, a
planet about the size of Mars smashed into us. It
knocked the Earth over, so instead of rotating around
an axis that is straight up and down, we are tilted by
This is what causes the seasons to change, not the distance to the
Sun (the Sun is actually CLOSER in WINTER). Because of this
tilt, the Earth has longer days in Summer, and more direct sunlight.
On North Pole, as the day passes,
what does an observer sees the
Sun do?
The Earth’s Orbit
Different constellations are out during different seasons. I can
see Orion and Taurus in the south during winter, but in summer
I see Scorpius and Sagittarius. This is because the night sky
faces different directions.
Polaris, the North Star is
directly over the north pole
Because stars are so
incredibly far away,
Polaris does not appear to
move during the night,
the Earth just spins
underneath it, everything
else rises in the east and
sets in the west, as the
Earth rotates.