Motion across the Sky

Learning goals We are learning how celestial objects move in our night sky. We are learning to distinguish between different types of satellites.

Ecliptic Ecliptic: the path across the sky that the Sun, the Moon, the planets, and the Zodiac constellations appear to follow over the course of a year

Changing Views in the Night Sky changing views in the night sky are due to: Earth’s rotation distance celestial object is from Earth Earth’s revolution around the Sun

Retrograde Motion retrograde motion: the apparent motion of an object in the sky from east to west, rather than west to east occurs because Earth travels around the Sun faster than the outer planets

satellites

history 1957 USSR: Sputnik 1 – size of football Sputnik 2 – much larger 1958 USA: Explorer 1 Alouette 1: Canada - 1962! Anik 1 in 1972: transimitted 12 tv channels

orbit Earth’s gravity pulls – satellite must have enough velocity Low earth orbit – up to 2000 kms military and earth observation International Space Station (430km above earth) travels at a speed of 27601 km/h

Geostationary orbit Satellite which orbits Earth at same rate as Earth rotates 35000 + km used to broadcast tv, radio and internet

gps Global Positioning System medium earth orbit (up to 35000km) uses three satellites to triangulate position

Learning goals We are learning how celestial objects move in our night sky. We are learning to distinguish between different types of satellites.

Homework: Section 8.9 #1, 3-7 Section 8.11 #7