Unit E – Space Exploration Lesson 4-3: (Sec 1.4 and 1.5) Our Solar Neighbourhood and Describing the Position of Objects in Space

A. Protoplanet Hypothesis model for explaining the birth of solar systems: 1. cloud of gas and dust begins swirling 2. >90% of material gathers in centre, forming sun 3. remaining material clumps together into planets and moons

B. The Sun surface temperature = 5500C core temperature = 15,000,000C (15 million degrees) emitted by sun are called charged particles solar wind Earth is protected from by its solar wind magnetic field

C. The Planets inner “terrestrial” planets are smaller and rockier Mercury Venus Earth Mars

outer “Jovian” planets are large and gaseous Jupiter Saturn Uranus Neptune

was the Pluto farthest planet until 2003 there is now a tenth planet with its own moon

D. Asteroids and Comets asteroids are between a few metres and a few hundred metres in size found in the asteroid belt between Mars and Jupiter Gaspra

comets are made of dust, rock and ice and move around the sun in elliptical paths when comets come close to the sun, gases are released by the heat, forming very long tails (millions of km) Halley’s Comet Hale-Bopp Comet Shoemaker-Levy Comet

E. Meteoroids, Meteors, Meteorites meteoroids are pieces of rock floating through space meteors are meteoroids that get pulled into the atmosphere…they glow brightly because of the heat of friction

meteorites are meteors that have hit the Earth’s surface

Describing the Position of Objects in Space 1.5 Describing the Position of Objects in Space

A. Positions of Objects to locate an object in space, two measurements need to be taken: 1. azimuth – compass direction in degrees from North eg) 0 = North, 180 = South 2. altitude – how high up in the sky eg) 0 = horizon, 90 = straight up an is called the altitude of 90 zenith

zenith

B. Motion of Objects other stars appear to be motionless…they move only slightly over long periods of time planets change positions in very short periods of time the through the sky is called the path the sun follows during the year ecliptic

Assignment Worksheet 4