Transcript The Solar System

The Solar System
The Solar System Contains:
• One star (the sun).
• Nine planets (well now there’s eight planets and
3 dwarf planets).
• 157 moons (at last count) orbiting the planets.
• Eight large asteroids.
• More than 100 Kuiper belt objects larger than
300 km in diameter.
• Tens of thousands of smaller asteroids, myriad
comets a few km in diameter, and countless
meteoroids less than 100 m across.
Planetary
Properties
• From closest to the sun,
we have Mercury, Venus,
Earth, Mars, Jupiter,
Saturn, Uranus, Neptune,
and Pluto (My Very
Educated Mother Just
Served Us Nine Pizzas).
• All planets orbit Sun
counterclockwise as seen
from Earth’s north pole
and in nearly the same
plane as the earth (only
Mercury and Pluto deviate
slightly).
Planetary Properties
• Earth’s radius is known using conventional surveying
techniques as well as satellite observations. Radii of
the other planets are determined by measuring their
angular radii (size as seen on the sky) and using
geometry to compute the physical radii.
• Mass is determined by observing a planet’s
gravitational influence on some nearby object and
applying Newton’s laws of motion and gravity (used
to use planets’ moons, now can also use artificial
satellites).
Planetary Properties
• 99.9 % of the mass in the solar system
is contained in the sun, whose gravity
dominates the motion of everything
else.
• Density is a measure of the
compactness of an object (mass /
volume).
Planetary Properties
Lecture Tutorial: Sun Size (p. 105)
• Work with a partner!
• Read the instructions and questions
carefully.
• Discuss the concepts and your answers
with one another. Take time to
understand it now!!!!
• Come to a consensus answer you both
agree on.
• If you get stuck or are not sure of your
answer, ask me or another group.
Terrestrial and Jovian Planets
• Inner planets - small, dense, and rocky in
composition. Called “terrestrial” planets since the
composition is similar to Earth’s. They are Mercury,
Venus, Earth, and Mars.
• Outer planets - large, low density, and gaseous.
Called “jovian” planets after Jupiter. They are Jupiter,
Saturn, Uranus, and Neptune.
• Note - Pluto does not fit into either of the above
categories! It has more in common with the icy jovian
moons than with any terrestrial or jovian planet.