Week of January 18, 2010

This week in science class we continued our study of Astronomy. In the beginning of the week we learned about direct and indirect light. Direct light is at a perpendicular angle , is smaller, and stronger. Indirect light is more spread out and has less strength. We also learned that we only see fifty percent of the moon, and no more than fifty percent is lit up. We see the moon phases because the moon revolves and rotates around the earth. This week we also learned the terms solstice and equinox. A solstice is when the sun reaches it's highest point (summer solstice) or lowest point (winter solstice) in the sky at noon, marked by the longest ( summer) and shortest (winter) days. This takes place on June 27 and December 27. An equinox is the time and date (twice a year) at which the sun crosses the celestial equator, when day and night are of equal length. This takes place on September 22 and March 20. Later in the week we took a quiz (ahhhh!) and watched a video. In the video David pushed a rolling bowling ball with a hammer to make it move in a circular shape. This brought us to the study of why the earth orbits the sun or why the moon orbits the earth without crashing into it. There are several that need to happen to get something to orbit another thing. First, the object or satellite has to be in motion. (Initial Velocity) If the initial velocity is too small it will crash into the object it is orbiting, but if it is too big the object that is orbiting will fly away (escape velocity). Second, Distance effects the amount of initial velocity necessary to orbit. The farther you are from the object you are orbiting the less initial velocity needed to put in orbit. But the closer you are to the object you are orbiting the more initial velocity needed to put in orbit. Lastly, the arrow direction (direction of velocity)should be perpendicular to the object you are orbiting. to learn this we practiced on our two imaginary planets Turtle and Juego!