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

4Guiding the ActivityHave students measure the string with theirmeasuring tapes and record its length ontheir activity sheets. Ask, How did the actualscale distance between Earth and Mooncompare with your predictions?Write satellite on the board. Ask, What is asatellite?Ask, Does anyone know the name of thefirst satellite to orbit Earth?Write natural satellite and artificial satelliteon the board. Explain that the Moon is anatural satellite. But point out that Earth alsohas many smaller manufactured satellites,or artificial satellites, that are used forcommunication, weather monitoring, andother data collection purposes.Have students predict on their activity sheetshow far from Earth most artificial satellitestravel.Then have teams take the tiniest dot of claythey can from their model Earth and hold itbetween Earth and the Moon, 20 cm (8 in.)from Earth. Explain that the position of thisbit of clay represents the altitude of some ofthe most distant Earth satellites! (See Figure5-3 for an accurate distance model of Earth’ssatellites.)Additional InformationAllow students time to express their surpriseor other responses. Students may beinterested to know that the true diameter ofEarth is about 12,800 km (8,000 mi) and themean distance from Earth to the Moon isabout 380,000 km (230,000 mi).Students may know that a satellite is anobject that orbits a planet.Students may answer with the name of anearly artificial satellite, but probably will saythat they do not know. The answer actually isthe Moon.Approximately 3,000 artificial satellites arecurrently in orbit around Earth.Each team also can hold up the Earth modeland a tiny speck of clay to demonstrate ateam prediction.This distance corresponds to an altitude ofabout 35,000 km (22,000 mi) and is thedistance of certain satellites that orbit Earthat the same rate at which Earth spins and,therefore, that maintain their position abovethe same spot on Earth at all times. The mostcommon satellites of this kind are theweather satellites that produce the picturesseen on television weather reports.the Earth, surrounded byartificial satellitesmost distant artificial satellitesthe Moon, Earth’snatural satellite Figure 5-3. An accurate distance model of Earth and its satellites (not accurate to size).delta science modules Earth, Moon, and Sun 49