The Solar System

What's a solar system?

Patterns in distances 1.4 – 1.8 times the distance of previous planet. 1.4 – 1.8 times the distance of previous planet. Mars to Jupiter doesn't fit. Mars to Jupiter doesn't fit. But asteroid belt where a planet should be But asteroid belt where a planet should be Brighter closer to Sun Brighter closer to Sun Warmer closer to Sun Warmer closer to Sun

SIZE= volume MASS= amount of matter DENSITY= mass / volume same mass but different densities Pattern in density?

How do scientists determine Size? eformula.asp eformula.asp

Patterns in size, composition, distance TERRESTRIAL Small size Low Mass Higher density Mostly rock Mercury, Venus, Earth, Mars JOVIAN Large size Massive Low density Mostly gas Jupiter, Saturn, Uranus, Neptune

How do scientists determine composition? Spectroscopy? Spectroscopy? How about terrestrial planets? How about terrestrial planets? – - Earth (and Moon), Mars, Venus – - Mercury?

How do scientists calculate mass? If it has a satellite If it has a satellite Kepler's 3 rd law relates semimajor axis, orbital period and mass Kepler's 3 rd law relates semimajor axis, orbital period and mass No satellite No satellite Spacecraft to measure gravity. Spacecraft to measure gravity. Calculate mass then compare to that of Earth. Calculate mass then compare to that of Earth. Then you can calculate density. Compare to Earth. Then you can calculate density. Compare to Earth. Make a best guess on composition based on comparisons Make a best guess on composition based on comparisons

How do scientists calculate gravity? g=-GM/(r*r) g=-GM/(r*r) g = acceleration of gravity (for Earth, g is approximately 9.81 m/s^2) G = universal gravitational constant = 6.67x10^-11 Nm^2/kg^2 M = mass of the object. (Earth M = 5.98x10^24kg) r = distance from the center of the gravitating body (Earth, r is approximately 6.38x10^6 m)

Patterns in Orbits Revolve counter-clockwise Rotate counterclockwise EXCEPT Venus, Uranus, Pluto, Triton orbit in same plane (orbital inclination of less than 7°) EXCEPT Pluto nearly circular orbits EXCEPT Pluto

Closer to Sun, less atmosphere, Farther, more atmosphere No atmosphere = more craters Why? How do we know Jovian's aren't pummeled with debris? Other patterns

Other stuff in the Solar System Pattern for moons? Pattern with rings?

Debris in Our Solar System Today Asteroids—rocky bodies several kilometers across which orbit the sun Meteor? Meteoroid? Meteorite? Oldest things in our Solar System. Comets Billions Chunks of rock and ice – Kuiper belt What's “ice”? Tail

How do scientists know the age of our solar system? Activity next week. Bring pennies! LOTS OF PENNIES!

clouds of gas and dust ejected from old stars gather into regions new stars can form How do we know? Nebula in Orion – birth of stars! Patterns are clues to the formation of our solar system

The Formation of a Solar System gas cloud collapses toward the center Why? condensation forms at the center, which is called a protostar. flattened disk of matter surrounds the protostar, which begins to shine Why?

The Formation of a Solar System The rising temperature from the sun removes the gas from the inner regions, leaving dust and larger debris. The planets establish dominance in their regions of the solar system. After almost all of the remaining gas, dust, and small debris has been collected by the larger objects, the solar system takes on the form we recognize today.

Other Star Systems Forming We can look at young star systems developing today. The planets orbiting these stars are formed from the surrounding disks of gas and dust, called protoplanetary disks or proplyds.

PLANET FORMATION Within the disk that surrounds the protosun, solid grains collide and clump together into planetesimals. The terrestrial planets are built up by collisions and the accretion of planetesimals by gravitational attraction. The jovian planets are formed by gas accretion.

Hawking Video

WHAT DID YOU KNOW? How many stars are there in the solar system? Only one star, the Sun. Was the solar system created as a direct result of the formation of the universe? No. All matter and energy were created by the Big Bang, but the solar system formed billions of years after the Big Bang. How long has the Earth existed? 4.6 billion years.

WHAT DID YOU KNOW? Is Pluto always the farthest planet from the Sun? No. Pluto’s orbit is highly eccentric, bringing the planet inside Neptune’s orbit for about 20 years every 250 years. What typical shapes do moons have? Most look roughly like potatoes.