Presentation on theme: "Topic II: Measuring the Earth"— Presentation transcript:
1Topic II: Measuring the Earth Regents Earth ScienceTopic II:Measuring the Earth
2Is the Earth Round?Not exactly………so Columbus wasn’t right!
3The Earth appears round but when “measured”, it is actually flattened at the poles and bulging at the equator…….**making the Earth a slightly, slightly, slightly, slightly Oblate SpheroidThis is not howIt looks!!!!
4How can we tell that the shape of Earth is nearly a sphere? Photographs from space (#1)
5Masts of ships appearing to “sink” as they travel past the horizon
6Gravity Measurements (more gravitational pull at the poles—closer to center of Earth = higher weight)
18How do you determine Latitude? The angle that Polaris makes with the horizon is equal to the person’s latitude (Polaris never moves)Altitude = Latitude
19Polaris Facts:Only seen in the Northern Hemisphere (not south of the Equator)Points Due (exactly) NorthNOT the brightest star in the sky!Use Pointer Stars to FindDirectly above North Pole“Big Dipper”—easy to see
20How do you determine Longitude? Find the time difference between your local time and Greenwich Mean Time (GMT) and then multiply by 15 (Greenwich is at 0 Longitude)This works because the Earth rotates 15 every hour and the Time Zones are 15 longitude apart (24 total, 1 hour apart)