Earth in Space

Astronomy The study of the moon, stars, and other objects in space = astronomy. Ancient astronomers studies the stars and the movements of the sun and moon. It was thought that the Earth was the center of the Universe and the moon and sun moved around us. We now know the Sun is the center of our universe and the Earth and all other objects (planets, moons and stars) orbit around the sun.

Rotation Earth has an imaginary line that runs from the north pole to the south pole – axis. The Earth spins around this axis = rotation 1 complete spin takes 24 hours and creates a day/night cycle. Rotational spin is from the west to the east The sun appears to rise in the east and set in the west. North South

Revolution Earth revolves, Orbits, around the sun 1 revolution – 1 year or 365 ¼ days February 29th, leap year, is added each 4th year to = 366 days Earth’s orbit around sun is not a perfect circle but more oval (elliptical). Winter’s distance from the sun is actually closer than summer’s distance.

Earth’s Seasons Earth is tilted on it’s axis at 23.5° Seasons occur due to this tilt. When the Northern Hemisphere is pointing toward the sun it is experiencing summer. Southern Hemisphere = winter When the Northern Hemisphere is pointing away from the sun it is experiencing winter. Southern Hemisphere = summer

Earth’s Seasons www.georgefcram.com/

Earth’s Seasons - Northern Hemisphere - Spring – March 21st Vernal Equinox Equal day and night Sun is directly over the equator Summer – June 21st Summer Solstice Longest amount of daylight hours Sun is directly over the Tropic of Cancer Fall – Sept 23rd Autumnal Equinox Winter – Dec. 22nd Winter Solstice Shortest amount of daylight hours Sun is directly over the Tropic of Capricorn

The Moon Moon revolves around the earth Moon also rotates on its axis Earth’s only satellite! 1 revolution – 1 month or 27.3 days Moon also rotates on its axis 1 rotation = 27.3 days Rotation = Revolutions 1 day = 1 year Same side of the moon always faces the earth!

Moon’s Orbit scssi.scetv.org/

Moon Phases As the moon revolves around the earth the amount of lit surface, visible from earth, is always changing. Waxing phases – lit surface is increasing Light on the right! Waxing Crescent 1st Quarter Waxing Gibbous Full Moon – full lit surface facing earth

Waxing Crescent Light on the RIGHT

First Quarter Moon Light on the RIGHT

Waxing Gibbous Light on the RIGHT

Full Moon

Moon Phases Waning phases – lit surface is decreasing Light on the left! Waning Gibbous 3rd Quarter Waning Crescent New Moon – no lit surface facing earth

Waning Gibbous Light on the LEFT!

3rd Quarter Moon Light on the LEFT!

Waning Crescent Light on the LEFT!

New Moon

Moon’s Phases www.astro.virginia.edu/

Eclipses On rare occasions during the moon’s revolution around the Earth, the moon or Earth completely blocks the sun from each other – Eclipse. The moon’s orbit is tilted at 5° so it rarely goes directly between the Earth and sun.

Solar Eclipse Occurs during a New Moon Moon is between the Earth and sun. Moon’s shadow is cast onto the Earth. Umbra – the smallest and darkest part of the moon’s shadow Only people within the umbra experience a total solar eclipse. Penumbra – largest part of the shadow outside the umbra that is not as dark. People within the penumbra experience a partial solar eclipse.

Lunar Eclipse Occurs during a Full Moon. The Earth is between the moon and sun. Earth’s shadow is cast on the moon. Can be seen anywhere on Earth that the moon is visible. Greater chance of seeing a total lunar eclipse than a total solar eclipse.

Tides The rise and fall of Earth’s water is controlled by the moon and its gravitational pull causing a daily cycle of tides. As Earth rotates, the moon’s gravity pulls the water toward the point on Earth closest to the moon. 2 high tides daily – every 12 hours 2 low tides daily – every 12 hours What is the time between a high and low tide? 6 hours

Tides The sun’s gravitational pull also affects Earth’s water. Spring tides – higher than high tides Sun, earth and moon are all aligned together occur twice a month on full moon and new moon Neap tides – tides with the least difference between high and low. Sun, earth and moon are at right angles to each other. occur twice a month 1st quarter and 3rd quarter Tide Simulation

Spring Tides www.redfishpro.org

Neap Tides www.redfishpro.org