-“creator” of Earth Day was Wisconsin senator Gaylord Nelson
-April 22 is always Earth Day
-EPA was created from all of the excitement of Earth Day
-20 million people participated in the first Earth Day
-several environmental acts passed in Congress because of Earth Day
Solstice
-comes from the Latin sol (the sun) and sistere (to stand still)
Summer Solstice
-Longest day of the year
-on June solstice, Northern Hemisphere soaks up the most sun of any day of the year
-24 hours of sun North of the Arctic Circle
-24 hours of darkness in Antarctica
-Happens at the same time of day across the Earth (ex: 11am in each time zone)
-occurs when the sun is over head at noon in the Tropic of Cancer at 23.5 degrees N
-shortest sunrise and sunset of the year
-at Stonehenge on the Summer Solstice, you can watch the sun rise over the stones; it is set almost perfectly for this occasion
Winter Solstice
-shortest day of the year
-darkest day of the year
-occurs when the sun is over head at noon in the Tropic of Capricorn at 23.5 degrees S
-New Grange in Ireland has a sight line that is directed to see the Winter Solstice sunrise
Seasons
-caused by the 23.5 degree tilt of the Earth’s axis
-aphelion- farthest point from the Sun that the Earth will reach- this year July 4th at 3am EDT; 94.5 million miles away from the Sun
-perihelion- closest point to the Sun that the Earth will reach- this past January 2nd; 91.4 million miles
-3.1 million miles between the two points; 3.3% difference which leads to a 7% difference in radiant heat
Equinox
-vernal equinox: the point where sun crosses the celestial equator from South to North; about March 21
-ver is Latin for spring
-autumnal equinox: the point where the sun crosses the celestial equator from North to South; about September 23
-autumnus is Latin for autumn
-night and day are equal- 12 hours light, 12 hours dark
-axis of the Earth points neither towards or away from the Sun
Eclipse
-occur when the satellite of a planet is located within .5 degrees of the plane of the ecliptic, on a line that passes through the center of the sun and the Earth
-in one calendar year, there are a maximum 5 solar eclipses and 3 lunar eclipses
-often occur in 3s- lunar, solar, lunar
-eclipse shadow moves at 2,000 miles per hour at the poles and 1,000 miles per hour at the equator
Solar Eclipse
-2-5 solar eclipses a year
-at any given point on the Earth, there is 1 eclipse every 360 years
-Saros Cycle: 18 year, 10 day for the entire orbit of the moon to precess once around its orbit plane so that the lunar nodes make one revolution
-takes 3 Saros Cycles for a solar eclipse to repeat in a nearby spot- 54 years and 33 days
-eclipses in Saros Cycle occur about a third of the way around the Earth from each other
-occur only during the new moon
-maximum time for Solar Eclipse is 7 minutes and 40 seconds
-maximum time for annular solar eclipse is 12 minutes and 24 seconds
-visible in a narrow path- maximum of 167 miles wide
-occurs 2 weeks before or after a Lunar Eclipse
Lunar Eclipse
-occurs only during a full moon
-maximum time for a lunar eclipse is 3 hours and 40 minutes
-maximum time the moon can stay in totality is 1 hour and 40 minutes
-occur up to 3 times a year
-visible over the entire hemisphere
Moon
-reflects light
-takes 29.5 days to orbit the Earth
-in the Southern Hemisphere, the moon phases are similar, but the moon appears opposite from how it appears in the Northern Hemisphere
-crescent that is waxing has a curve like a “C” in the SH; waning in the NH
Moon Phases
-if the moon is smaller than a quarter, then the moon is in a crescent phase
-if the moon is larger than a quarter, then the moon is in a gibbous phase
-when the moon is getting bigger, the moon is waxing
-when the moon is getting smaller, the moon is waning
-when the crescent has a curve like a “D”, the moon is waxing
-when the crescent has a curve like a “C”, the moon is waning
-new moon is the first phase
-waxing crescent is the next phase
-then first quarter
-waxing gibbous
-full moon
-waning gibbous
-last quarter
-waning crescent
-then the cycle starts over at new moon
Daylight Saving Time (DST)
-even though most people say Daylight Savings Time, it is actually Daylight Saving Time
-starts at 2 am on the 2nd Sunday in March
-ends at 2 am on the 1st Sunday in November
-Not observed in: Hawaii, most of Arizona (except the Navajo Indian Reservation), American Samoa, Guam, Puerto Rico, and the Virgin Islands
-observed over most of the world
-not observed near the equator or in tropical locations because the amount of daylight is about the same
-in the Southern Hemisphere, DST is observed from October to March since their summer is opposite of the Northern Hemisphere
-DST saves electricity
-in 1784, Benjamin Franklin was the first to advocate for DST because he saw people wasting candles late and night and sleeping past dawn
-in 1883, railroads started standard time zones so that they could print when the trains would come
-Congress passed standard time zones for the country in 1918
-this law also included DST, but it was repealed in 1919 and left to the states to decide
-in 1966 Congress passed the Uniform Time Act, standardizing the beginning and the end of DST, still leaving the states the option to participate
-Indiana, which was divided between 2 time zones, didn’t use DST until 2005, which is when they decided to adopt it
-in 2007, Congress updated the time changes from April and October to March and November