The Earth-Moon System The Earth-Moon System - Delta Education

ConnectionsScience ChallengeChristopher Columbus discovered that steadywinds, now called trade winds, blow fromeast to west in the southern Atlantic and fromwest to east in the northern Atlantic. Prior toColumbus’s discovery, most sailors believedthat winds were due to the whims of gods ordemons. Scientists did not learn why tradewinds exist until two centuries later.Challenge students to research EdmundHalley’s and George Hadley’s work to explainhow Earth’s rotation and orientation createthe trade winds.Science and the ArtsPerspective determines the apparent distanceof objects. Display examples of medieval art,created before formal rules for perspectivewere developed, alongside Renaissanceworks that demonstrate perspective.Then have team members take turns holdingthe model Moon at an appropriate distancefrom Earth while other team members viewthe model from various perspectives: a sideview, the viewpoint from Earth, the viewpointof someone traveling to the Moon, and theviewpoint from the Moon.the amount of parallax is greater for objectsclose to the viewer than for distant objects,an object’s distance can be determined by itsparallax.Have students trace two circles near oppositeends of a sheet of paper to represent theMoon and Earth. Earth’s diameter should beabout 2 cm (0.75 in.) and the Moon’s, about0.5 cm (0.2 in.). Then they should draw a dotbeyond and to one side of the Moon torepresent a star and two separate dots on theside of Earth facing the Moon to representtwo astronomers at different locations. Usinga ruler, students should draw four straightlines, one from each astronomer to the starand one from each astronomer along thecircumference of the Moon. Using aprotractor, students should measure theangle between the Moon and the star fromthe perspective of each astronomer. What isthe difference—the parallax—between them?Then have students tape sheets of papertogether so that the Moon can be 60 cm(24 in.) away, its actual scale distance. Howdoes parallax change as the distance to theMoon increases?Science and MathThe distance from Earth to the Moon wasfirst measured about 2,000 years ago byHipparchus, a Greek astronomer, usingparallax. He and a distant colleague bothmeasured the angle between the Moon anda particular star on a particular night.Have students hold a finger near the tip oftheir nose and view it, first closing one eyeand then the other. Have them view an objectacross the room and a distant tree or buildingin the same way. Do the distant views vary byeye as much as the nearby finger? Explainthat the difference between the view with oneeye and the other is called parallax. Becausedelta science modules Earth, Moon, and Sun 51