Download Guided Notes on the Sun-Moon

Guided Notes on the SunMoon-Earth System
Chapter 28, Section 3
1.
Every society, from ancient times
to the present, has based its
calendar and its timekeeping
system on the apparent motions
of the Sun and Moon.
2. The Sun rises in the east and sets
in the west, as do the Moon,
planets and stars. These daily
motions result from the Earth’s
rotation.
3. Annual changes in the length of
the day and the average daily
temperature are the result of
Earth’s orbital motion about the
Sun.
4. The plane in which Earth orbits is called the
ecliptic. Earth’s axis is tilted relative to the
ecliptic at about 23.5˚. As the Earth orbits
the Sun, the orientation of the axis remains
fixed in space. At one point, the northern
hemisphere is tilted toward the Sun, while
six months later, it is tipped away from the
Sun. Our seasons are created by this tilt
and by Earth’s orbital motion around the
Sun.
5. On the day of the summer solstice,
the Sun is directly overhead at the
Tropic of Cancer, which is 23.5%
North latitude. This occurs each year
around June 21st, and is the day when
the number of daylight hours for the
northern hemisphere is at its
maximum. Daylight is at a minimum
for the Southern hemisphere.
6. On the day of the winter solstice, the
Sun is directly overhead at the Tropic
of Capricorn, which is 23.5% South
latitude. This occurs each year
around December 21st, and is the day
when the number of daylight hours for
the northern hemisphere is at its
minimum. Daylight is at a maximum
for the Southern hemisphere.
7.
The lengths of day and night
are equal for both the northern
and southern hemispheres on
the autumnal equinox and the
vernal equinox.
8.
A solar eclipse occurs when
the Moon passes directly
between the Sun and Earth
and blocks our view of the
Sun.
9. A total solar eclipse occurs when
the Moon perfectly blocks the
sun’s disk, and we see only the
dim, outer gaseous layers of the
Sun.
10.Total solar eclipses are only
visible from a very small portion
of the Earth, while partial eclipses
are visible from a much larger
portion.
11.Only when the Moon crosses the
ecliptic is it possible for the
proper alignment for a solar
eclipse to occur. When the
intersection of the Moon and the
ecliptic is in line with the Sun and
the Earth, a total solar eclipse
can be seen.
12.The Moon’s distance from the
Earth increases and decreases
as the Moon moves in its elliptical
orbit around Earth. The closest
point in the Moon’s orbit is called
the perigee and the farthest point
is the apogee.
13.A lunar eclipse occurs when the
Moon passes through the Earth’s
shadow. This can only happen
during a full moon, when the
moon is in the opposite direction
from the Sun.
14.Solar and lunar eclipses occur in
almost equal numbers. The
maximum number of eclipses that
can be seen in one year is seven.
The last time that this happened
was in 1982, and it will not occur
again until 2038.