Presentation on theme: "Earth in Space (a work in progress) Dr. Alan F. Weekes."— Presentation transcript:
Earth in Space (a work in progress) Dr. Alan F. Weekes
Astronomy Possibly the oldest science Contrast with astrology: belief system The belief that the positions of the planets and the sun at the time of your birth affects your personality and your future.
Calendars Seasons, festivals, time, flood of the Nile Year The time it takes for the sun to rise in the same place ~365 ¼ days Month Roughly the time for the moon to go through its set of phases Some cultures exactly a month, from new moon to new moon Asian, Jewish, Moslem 29.5 days from new moon to new moon
Day –from sunrise to sunrise –24 hr. Week –Named for visible moving objects in the sky –Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn –Sunday, Monday, Saturday –Tiwes Day (Mars), Wodens Day (Mercury), Thors Day (Jupiter), Friges Day (Venus) –lunes, martes, miercoles, jueves, viernes, sabado, domingo
A Little History Geocentric Theory Earth is the center of the universe Everything revolves around the earth What is apparent, what is observed agrees with some religious views
Heliocentric Theory Sun: the center of the solar system Copernicus ( February 19, 1473 – May 24, 1543) –Polish priest, astronomer Considered heretical, not published until his death bed in 1543 –People were arrested, tortured and killed for teaching this idea –Galileo under house arrest for years for this idea Nicholas Copernicus Giordano Bruno Galileo Galilei
Motions of the Earth Revolution Time it takes to revolve around another body, the sun. Year 365.24 days for the Earth Leap years are determined according to the following rule: –Every year that is exactly divisible by 4 is a leap year –except for years that are exactly divisible by 100; these centurial years are leap years only if they are exactly divisible by 400. Note: The Earth is held in its orbit by the Suns gravity.
Rotation The time it takes for a body to rotate about an axis Day –23 hr. 56 min. for the Earth –Relative to distant objects –24 hr for sunrise to sunrise –The earth has moved a bit in its orbit relative to the sun, so it takes a little longer for the sun to be visible –~1000 mph at the equator, 800 mph here
Other important characteristics Size- diameter: 12,756.3 km (7,926 mi) Orbit: 149,600,000 km (93,500,000 mi) from Sun 1.00 astronomical unit (au) from Sun Elliptical, not circular More of a squashed circle –Closest to the sun on Jan. 4, 147.5 million km –Farthest from the sun July 4, 152.6 million km Mass: 5.9972x10 24 kg
Science 8 Goby Last Video: Basic Astronomy Per. ___ 9/13/13 5 Things new or interesting to you in the video. 1. 2. 3.
The Seasons The earth is tilted in its orbit around the sun at 23.5 o The earth is always tilted in the same direction, North Star over the North Pole 23. 5 o North Latitude- Tropic of Cancer 23. 5 o South Latitude- Tropic of Capricorn 66.5 o North Latitude- Arctic Circle 66.5 o South Latitude- Antarctic Circle
Seasons are determined by where the most direct rays of the sun are hitting the Earth.
Old Farmers Almanac Site Seasons of 2013: SPRING EQUINOXMarch 20, 7:02 A.M. EDT SUMMER SOLSTICEJune 21, 1:04 A.M. EDT FALL EQUINOXSeptember 22, 4:44 P.M. EDT WINTER SOLSTICEDecember 21, 12:11 P.M. EST
The Earths Moon Earths companion in space Large in relation to the Earth About ¼ diameter of Earth, approx. the size of the U.S. from coast to coast Diameter: 3,476 km (2,172 mi) Distance from Earth Orbit: 384,400 km (240,000 mi) Mass: 7.35e22 kg Gravity, about 1/6 of Earths
Features of the Moon Craters Made by impacts with meteorites Mare seas made by the outpouring of lava early in the moons history Rays Bright lines extending out from some newer craters
The Moons Motions Rotation- about 27 1/3 days Revolution- about 27 1/3 days –The moon keeps the same side toward the Earth as it goes around the Earth –The moon is held in its orbit by the gravitational attraction between the Earth and the moon.
The Moons Phases The geometry of the Earth- Moon- Sun determines the phases of the moon With the phases of the moon, we are seeing different amounts of the lit portion of the moon. ½ of the moon is always illuminated by the sun.
Eclipses Named after what goes dark. Solar eclipse Moon comes between the Earth and the sun. Occurs during a new moon. Only a small area sees it (totality). Next one here, August 21, 2017August 21, 2017
The Tides The tides in the ocean are a result of the gravitational attraction of the moon and sun on the earth. There is always a bulge of water facing toward the moon and one away from it. When you are under a bulge, you have high tide. When you are between bulges, you have low tide. The sun also influences tides The greatest range is at full and new moon, straight line, spring tide. The least range is at the quarter moons, right angle, neap tide.