Our Solar System (Section 6.1 page 146) An Inventory of the Solar System

Greek Astronomers’ Solar System Moon Stars 5 planets: _______, ________, _________, _______, _______ _______: long wispy strands of light that were visible for weeks and slowly faded ________: shooting stars, bright streaks of light that shoot across the night sky.

17 th Century Solar System Galileo used a telescope to discover: ___________________ and ______________________

19 th Century Solar System Saturn's’ Rings _________ (year) Uranus ____________ (year) Neptune ___________ (year) Minor planets called ___________ The ____________ Belt between Mars and Jupiter Ceres ________

20 th Century Solar System Kuiper Belt beyond Neptune Non-optical “seeing” using ____ and _____ waves Space flight: manned space craft and un-manned space probes ***Most accepted theory of its formation: planets were formed from the same gas cloud that formed the sun Hubble Telescope

Let’s Take A Stroll It seems that half of all stars are _________________________ Our solar system is centered around a single star; the Sun. Planets, in order of distance from the Sun: M_______, V_____, E____, M___, J______, S______, U______, N______ My Very Exceptional Mother Just Served Us Nachos

Let’s Take A Stroll Some of the planets have moons, totaling _____ at last count. By the 1990’s, observed more than 6,000 large ________. More than 1 million with diameters greater than 1 km. They are debris from the formation of the Sun.

Overall Layout of the Solar System (Section 6.3 page 149) It’s IMMENSE! HUGE! _________ AU across (that’s ______________ miles)

Overall Layout of the Solar System (Section 6.3 page 149) Orbits of all planets are ________ The Sun is at one _____ of the elliptical orbits. They are not evenly spaced, (they become _________ apart the farther out from the sun) They all rotate __________wise All lie nearly on the same orbital plane except Mercury (7°) Asteroid belt lies between _________ and _________. Most of the solar system’s asteroids are here.

Comparative Planetology (pg. 147) Comparing and contrasting the properties of the diverse planets and the conditions under which they evolve

Measuring the Planets (Sec. 6.2 pg. 148) Distance:_______________ Orbital period:____________ Radius:_________________ Mass:___________________ Rotational period:__________ Density:__________________

Distances Astronomers have agreed on the astronomical unit (Au) – the average distance between Earth and the Sun 1 AU = 92,754,170 miles Sun to Pluto = 40 AU If Earth were a golf ball……  Pluto would be a pea about 8 miles away  Jupiter would be a basketball 1 mile away  Sun would fill a 10 ft 2 room less than ¼ mile away!

Distances First determined by Kepler’s Laws, then radar ranging Seems very far, but compared to the nearest star, the planets are next door neighbors. Alpha Centauri (nearest star) is 4.3 light years away. Golf ball scale: it would be 55,000 miles away!

Orbital (sidereal) Period How long a ‘year’ is on the planet Measured relative to the stars Shortest: Mercury ______ earth years  Closest distance to Sun Longest: Neptune ______ earth years  Farthest distance from Sun How long is Mars’ year? _______

Radius (or angular diameter) Planets size or width Measured using geometry

The Mass of the Planet Can be easily calculated if the planet has a moon Newton’s Laws of motion and Law of Gravity Determined by how the planets’ and moons’ gravity influence each other. I’m pulling you! NO, I’m pulling you!

At the Center… Sort of The Sun contains 99.9% of all matter in the solar system. Jupiter is the largest planet, almost 300 times the mass of Earth. The Sun is more than 1,000 times the mass of Jupiter!

Rotational Period Time it takes to ‘spin’ How long is a ‘day’ Determined by watching the surface features appear and alternately disappear as it rotates. Can be difficult to determine if…  ___________ (Mercury)  ____________ (Venus)  ____________ (Jupiter)

Density (Table 6.1) Compactness of the matter of the planet The planets Mass / Volume Measured in kg/m 3 or g/cm 3 Earth has a density of 5.5 g/cm 3 Jupiter’s density of _____g/cm 3 (mmmm. Why so much smaller than Earth????)

Bell Work: Which planet has the … 1. Most mass, least mass? 2. Longest day, shortest day? 3. Most moons, least # moons? 4. Most density, least density? 5. Highest temperature, lowest temp? Jupiter, mercury Venus, Jupiter Jupiter, mercury Earth, Saturn, Venus, Uranus

Inner planets vs Outer planets Terrestrial Jovian

The Inner and Outer Circles Planets fall into two broad categories Terrestrial: four planets closest to the Sun; rocky Jovian: farthest from the Sun; gaseous Pluto is more of a rogue moon than anything else.

The Terrestrial Planets What they have in common: - _____ proximity to the Sun, -relatively _____ spaced orbits -_____ masses -_____ radii -_____ density -_____ rotations than jovian planets -have _____ magnetic fields -have ______ or _____ moons.

The Jovian Planets pg ) What they have in common: -_____ from the Sun -_____ spaced orbits -______ size -________radii (size) -_________density -predominantly _______ (make up) -no _____ surface -rotate ___________ -possess ______ magnetic fields -orbited by many __________. - all have ______

Bellwork: True/False 1. The largest planets have the largest density. 2. The jovian planets rotate faster than earth. 3. All Inner and outer planets have moons. 4. The terrestrial planets are gaseous. 5. The jovian planets are more closely spaced. 6. The jovian planets have rings.

The Asteroid Belt Review Between Mars an Jupiter Astronomers have cataloged more than 6,000 asteroids with regular orbits. Size of individual asteroids: comparable to a small city All orbit in the same direction as Earth except one, which is retrograde. The ellipses (tilt) of the asteroids tend to be more exaggerated than the planets.

Large Asteroid or Dwarf Planet? Ceres 950 km wide  (590 miles) In 2006, Ceres was upgraded from an asteroid a ‘dwarf planet’ Pluto 2300 km wide  (1430 miles)  At the same time, Pluto was down-graded from a planet to a dwarf planet

PBS video clip o/index.html

According to the International Astronomical Union (August 2006)... A PLANET is a celestial body that: (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighborhood around its orbit. There are eight planets under this definition: Mercury, Earth, Venus, Mars, Jupiter, Saturn, Uranus and Neptune. A DWARF PLANET is a celestial body that: (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, (c) has not cleared the neighborhood around its orbit, and (d) is not a satellite.

What killed the dinosaurs? Page 366 Discovery 14-1