Sun, Moon, & Earth’s Motions

Sun’s Motion

Sun’s Apparent Motion

Summer Most hours of sunlight Sun RISES in the EAST and SETS in the WEST

Winter Least hours of daylight Sun RISES in the EAST and SETS in the WEST

Fall and Spring Equal hours of daylight Sun RISES in the EAST and SETS in the WEST

Summer Solstice June 21 North Pole is tilted toward the Sun Sun is highest in the Sky Longest day, shortest night

Winter Solstice December 21 North Pole is tilted away from the Sun Sun is lowest in the Sky Short Day, Long Night

Fall (Autumnal) Equinox September 23 Sun is directly over the equator Equal hours of day and night

Spring (Vernal) Equinox March 21 Sun is directly over the equator Equal day and night

Earth’s Motion

Rotation Earth rotates on an imaginary axis Axis- imaginary line from the North Pole to the South Pole through Earth 23.5˚ Earth’s tilt Earth’s rotation= counterclockwise Tilt causes seasons

Proof of Rotation Foucault’s Pendulum Coriolis Effect

Foucault’s Pendulum The path of the pendulum appears to change. Actually, the pendulum swings in a fixed direction in space, while Earth…and the observer, rotates under the pendulum.

Coriolis Effect

Revolution Earth revolves around the Sun once every 365 days

Evidence of Revolution Changing background of stars

Nutation Rocking, Swaying, or Nodding Motion in the axis of rotation on Earth Sun and Moon, which causes tidal force, continuously change location relative to each other and cause nutation

Precession Slow and continuous change in Earth’s rotational axis or orbital path Earth goes through a precessional cycle 1˚ every 72 years during which the positions of stars will slowly change Over this cycle, Earth's north axial pole moves from where it is now, within 1° of Polaris, in a circle around the ecliptic pole, with an angular radius of about 23.5 degrees.

Reminders If it happens everyday Due to Rotation of Earth If it happens every year or seasonally Due to Revolution of Earth around Sun

Moon Phases

The Moon Revolves around the Earth every 27.3 days, but takes 29.5 days from one full moon to the next Moon’s tilt is 5˚ Rotates every 27.3 days (why we only see one side of the moon)

Moon Phases Side lit up by the Sun is visible to Earth, we see the Moon Revolution and changing of light visible on Earth causes moon phases

Seasons

Seasons Caused by Earth’s tilt toward or away from the Sun Northern End tilts toward Sun, more direct rays=Summer

Spring March 21 Summer June 21 Winter December 21 Fall September 23

Tides

Tides Caused by the gravitational pull of the Moon and Sun on Earth Mostly caused by the Moon since it is closer to Earth (more force of gravity)

High Tide Located directly under the Moon’s position and on the opposite side of the Earth Pull of the Moon is strong

Low Tide Located at right angles to the high tide Pull from the Moon is smallest

Cycle We experience 2 high tides and 2 low tides Each cycle takes 24 hours and 50 minutes to complete since the Earth rotates and the Moon revolves Between 2 high tides there is a period of 12 hours and 25 minutes

Spring Tide Caused by a full and new moon Water goes from its highest level to its lowest level for the month

Neap Tide Caused by the half moon phases High is not so high, while the low is not so low

Solar Eclipse

What is it? Occurs when the Moon passes between the Sun and the Earth and the Moon partially or fully blocks the Sun Only happen in new moon phase

Partial and Annular Eclipse

Total Eclipse

November 13, 2012

Lunar Eclipse

What is it? Moon passes directly behind the Earth into its shadow Occurs when Sun, Moon, Earth are aligned exactly with Earth in the middle Occurs night of a full moon

November 28, 2012