Post on 13-Jan-2016
Space CyclesReview
Cycle # 1
Day Night Day Night
We have day and night because the Earth ROTATES
• On it’s axis• Once every 24
¼ hours• ½ of the Earth
is illuminated (lit up) at a time
http://www.gcse.com/eb/day2.gif
Cycle #2The length of days
Long Longer Longest Longer Long Short Shorter Shortest Short Shorter Shortest Long Longer
Longest
The length of day changes during the year
• The number of hours of daylight is different at different times of the year
• The number of hours of daylight is different at different latitudes
Summary
• Days are longer (more hours of daylight) in summer, shorter in winter
• There are greater differences in day length further away from the Equator
• There is not much change in day length near the Equator
Summary
• Days get LONGER (more minutes of daylight each day) from the Winter Solstice to the Summer Solstice
• Days get SHORTER (fewer minutes of daylight each day) from the Summer Solstice to the Winter Solstice
• Day length is about EQUAL everywhere in the world on the Autumnal & Vernal Equinox
Why does the length of day change?
• Because the Earth moves, or REVOLVES around the Sun
• This changes the way sunlight hits the Earth
Cycle # 3The Seasons
Winter Spring Summer Fall Winter Spring Summer
http://www.getyourwebsitehere.com
Seasons are caused by
• The tilt of the Earth
• The position of Earth in space
• The difference in direct and indirect light from the Sun
Summary
• In winter:– Part of the Earth
is tilted AWAY from the Sun
– Part of the Earth gets INDIRECT energy from the Sun
• In summer– Part of the Earth
is tilted TOWARD the Sun
– Part of the Earth gets DIRECT energy from the Sun
The position of the Earth in space determines which part of the planet is tilted toward the Sun.
Cycle # 4Moon Phases
New moon Waxing Crescent 1st Quarter Waxing Gibbous Full
Moon Waning Gibbous 3rd Quarter Waning Crescent New Moon
The Moon
• A moon phase cycle (LUNAR CYCLE) lasts 29 1/2 days
• Moon phases are caused by the positions of the Moon, Sun, and Earth
• The moon also sees Earth phases
http://www.astro.virginia.edu
What we see on Earth
compared to the position of the moon in
space
DAY 1 The Moon's unilluminated (not lit by the Sun)
side is facing the Earth. The Moon is not visible.
New Moon
DAY 3The Moon seems to be getting bigger –
more of the lit side is showing.
WAXING CRESCENT
Getting bigger:
WAXING
The RIGHT ½ of the
moon is lit
Less than ½ the moon showing:
CRESCENT
FIRST QUARTER
DAY 7One-half of the Moon is illuminated by
direct sunlight.
One half of one half of the moon is
visible.
Waxing Gibbous
DAY 11The Moon is more than one-half but not fully
illuminated by direct sunlight.
GIBBOUS: more than half of the moon is visible.
Full Moon
DAY 14The Moon's illuminated side is facing the Earth.
The Moon is completelyilluminated by direct sunlight.
Waning Gibbous
DAY 17The Moon is more than one-half but not fully
illuminated by direct sunlight.
Waning: getting smaller.
Moon is lit on the LEFT
side
Last Quarter
DAY 22One-half of the Moon is illuminated
by direct sunlight.
Waning Crescent
DAY 24The Moon is less than one-half illuminated by direct sunlight.
Summary