Elyse+and+Brittany

Stonehenge The Stonehenge is a central circle of 40-ton upright stones standing capped by 10-ton horizontal lintels. The Stonehenge was built in about 2200-2500 BC. Who actually built the Stonehenge is still unanswered today. Most would guess it was built by ancient Britons and possibly religious people and astronomers. The Stonehenge was said to be aligned with the sun and was used to observe the sun, moon, stars, and eclipses. Other possibilities of its use was as a sun temple, tomb, social gathering, religious assemblies, observatory, celestial temple, and burial ground.  Eratosthenes Eratosthenes was a Mathematician, poet, athlete, geographer, and astronomer from Greece. He created the system of Latitude and Longitude which helped him measure the circumference of the Earth. He also created a map of the world, and founded the Scientific Chronology. He was the first Greek to accurately measure the tilt of the earth’s axis, and also invented Leap Day, and could have possibly calculated the distance from the Earth to the Sun. For Eratosthenes to measure the circumference of the Earth he knew that at noon, in the city of Swenet or Syene-in Greek, located on the Tropic of Cancer- on the day of the Summer Solstice the sun would appear directly overhead(Zenith). He also knew that Alexandria, his home town was “1/50 of a full circle” south of the Zenith. Knowing that Alexandria was north of Syene he calculated that the distance of the two cities was 1/50 “the total circumference of the Earth.” The distance he came up with was rounded and used in comparison to a huge stadium. Kepler's Laws Kepler's laws are mathematical laws that describe the motion of planets in our solar system. Kepler's first law of planetary motion states that every planet orbits the sun in the shape of an ellipse. An ellipse is like an oval or a stretched out circle. This was a huge discovery because before Kepler's first law everyone believed that the planets orbited the sun in a circle. Kepler's second law of planetary motion states that a line joining a planet and the sun sweeps out equal areas during equal intervals of time. This law is also known as the law of equal areas. So pretty much if a planet takes one day to travel from one point to another around the sun then it will cover the same distance in that same amounts of time no matter where it is in it's orbie. This also means that since the planet moves in an ellipse and not a perfect cirlce the planet must travel faster when it is closer to the sun so it sweeps the same amound of area. Kepler's first and second law relate very much to each other stating that a planet orbit's the sun in an ellipse and covers the same amount of area in the same amount of time regardless or where it is located.
 * Historical Astronomy Project**

Works Cited Dan, Falk. "Did ancient astronomers build Stonehenge? ." __Science Reference Center__. 2008. EBSCOHost. 3 Mar 2009 . "Stonehenge." __Wikipedia__. 2 Mar 2009 . "Eratosthenes." __Wikipedia__. 2009. 3 Mar 2009 .

"Kepler's Law of Planetary Motion." __Wikipedia.__ 28 Feb 2009. Wikimedia Foundation Inc.. 2 Mar 2009 [].

Elyse DeVos Block 3 3/22/09 The study of astronomy has indeed changed over time. The first study of astronomy was simply noticing objects in the sky such as the stars, the sun, and the moon. As the study flourished people began using the stars to keep track of time, seasons, and even phases of the moon. As man’s knowledge of the outside sky began to grow, new and unique methods of research did as well. Astronomers began to use telescopes, cameras, computers, satellites, graphs, maps, the red shift, x-rays, and many more methods to learn more about our universe. Many ideas have changed over time such as the orbits of planets, the center of the universe, and the Big Bang theory. Now today instead of observing what use to be just little shinny dots in the sky we are observing planets, stars, galaxies, black holes, worm holes, space travel, and even the possibility of life on other planets. And the study of astronomy will keep changing over time opening up more and more possibilities about our universe.