sec. 7.4 the planets
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the solar system song. Sec. 7.4 The Planets. Name the planets in our Solar system. In order of increasing distance from the sun Your task: research, model planet assigned to your group. Some things to know. - PowerPoint PPT PresentationTRANSCRIPT
Name the planets in our Solar system
In order of increasing distance from the sun
Your task: research, model planet assigned to your group
Some things to know...
Planet = an object that orbits one or more stars, is spherical and does not share it’s orbit.
Classification of planets: Inner planets (terrestrial) Relatively small, rocky crust Eg.
Outer Planets (gas giants) Large clumps of gas, ice and dust Eg.
Our Solar system
Solar syst. = the planets, or sun and other smaller objects that circle it.
Early thoughts: The first model of the solar system
stated that Earth was the centre of our solar system; Geocentric model.
In 1500s Copernicus argued the heliocentric model.
Observing planets
Planet vs. Star How do you know which is which?
Venus, Mercury visible early evening or morning why?
Mars, Jupiter, Saturn seen along with other stars moving westward in sky. When Earth “catches up to them” they exhibit retrograde motion.
retro motion of mars
Comparing the planets, terms to know
Astronomical Unit: AU is equal to the average distance between Earth and the Sun (150 million kilometers)
Earth’s orbital radius= 1AUMercury orbital radius = 0.39Neptune orbital radius = 30.06AU
(in other words, Neptune is 4500 million km. away)
Light year
1 light year = the DISTANCE light can travel in 1 year OR 10 X 1015 km
So what?-it takes light from Sun 8.32min to reach the
Earth-Oort Cloud is about 2 light years in Diameter-Milky way (center of our Galaxy) is
26kilolightyears away Sirius is 8 ly away