Unit 2: The Solar System

Mrs. Morgan8th Grade

The Big IdeaPlanets and a variety of other bodies form a system of objects orbiting the sun.

The Center of the Solar System

Unit 2 Lesson 1 Historical Models of the Solar System

•Solar system - the sun & all of the bodies that orbit the sun.

•Heliocentric model – Sun centered, Earth and the other planets orbit the sun.•Geocentric model – Earth centered, the sun, moon and planets circling the Earth

In the beginning…Aristotle (384-322 BCE)-believed in a geocentric model, part of his logic was that we could feel no motion on Earth, so Earth couldn’t be moving. He thought we should detect a shift in position between nearby stars and far away ones.

• Parallax- apparent shift in the position of an object when viewed from different locations.

Unit 2 Lesson 1 Historical Models of the Solar System

Aristarchus (about 320 230 BCE)- proposed a heliocentric model, his attempts to measure relative distances to moon & sun have been major contribution to science

http://www.astro.cornell.edu/academics/courses/astro2201/aristarchus.htm

Unit 2 Lesson 1 Historical Models of the Solar System

Ptolemy- (100-170 CE) believed in a geocentric model.

• His model was used for 14 centuries.

• Planets moved on small circles that in turn moved on larger circles (“wheels-on-wheels”)

• Allowed people to predict the motions of planets years into the future.

Unit 2 Lesson 1 Historical Models of the Solar System

Copernicus- (1473-1543) believed in a heliocentric model with perfect

circles

Kepler- (1571-1630)Realized that planetary orbits were not circular but were more like ellipses.

Unit 2 Lesson 1 Historical Models of the Solar System

Galileo Galilei (1564-1642)

Improved the telescope in 1609

Observed Jupiter’s moons, Io, Europa, Callisto, and Ganymede which gave support of heliocentric model

Observed Venus’s phases

Unit 2 Lesson 1 Historical Models of the Solar System

Gravity - force of attraction between objects that is due to their masses & the distances between them. Every object in the

universe pulls on every other object.

Orbit - path that a body follows as it travels around another body in space.

Unit 2 Lesson 2 Gravity & the Solar System

http://kissedgoodbye.blogspot.com/2012/01/gravity.html

Kepler’s Three Laws

1. Planetary orbits are ellipses with the sun at one focus

Aphelion- where the object is farthest from the sun.

Perihelion - where the object is closest to the sun.

2. Planets move faster in their orbits when they are closer to the sun.

3. Distance of a planet from the sun to the time the planet takes to go once around its orbit.

Unit 2 Lesson 2 Gravity & the Solar System

Law of Gravitational Force

Law of universal gravitation- states that all objects in the universe attract each other through gravitational force.• Centripetal force -inward force

that causes an object to move in a circular path.

When planets orbit the sun, a force similar to centripetal force prevents them from moving out of their orbits and into a straight line.

The sun’s gravity is the force that keeps the planets moving in orbit around the sun.

http://www.teachersdomain.org/resource/phy03.sci.phys.mfw.roller/

Unit 2 Lesson 2 Gravity & the Solar System

http://www2.nido.cl/~science/ksupplee/Mechanics/circular%20motion/uniform%20circular%20motion.html

How the Solar System Formed Theory

Solar Nebula - inward pull of gravity is balanced by the outward push of gas pressure in the cloud (perhaps the explosion of a nearby star)• Planetesimals - Collisions between these bodies

formed larger bodies from which planets formed

Here Comes the Sun• Corona-outer

atmosphere of the sun (up to 2,000,000 ˚C)

• Chromosphere-middle layer of sun’s atmosphere (6,000 ˚C)

• Photosphere- visible surface of the sun. Energy escapes into space (5,527 ˚C)

Unit 2 Lesson 3 The Sun

• Convective Zone – energy travels by convection from the radiative zone to the photosphere

• Radiative Zone - energy is transferred away from the core by radiation.

Core – very dense center of sun. Temperature of 15,000,000 ˚ C, where nuclear fusion occurs.

Unit 2 Lesson 3 The Sun

Solar Activity

Sunspots-dark areas that form on the surface of the sun.

Unit 2 Lesson 3 The Sun

Solar flare – an explosive release of energy

that can extend outward as far as the sun’s outer atmosphere Prominence- huge loops of relatively cool gas that extend outward from the photosphere

Nuclear Fusion - process by which two or more low-mass atomic nuclei fuse to form another, heavier nucleus.

Three Steps of Nuclear Fusion in the Sun

1. Deuterium - 2 H+ collide (1 P, 1 N- a heavy hydrogen)

2. Helium-3 – deuterium combines w/ another H+ (more energy/ gamma rays released)

3. Helium-4 – 2 He-3 nuclei combine to form He-4 (more energy/pair of H+ released)

turn to pgs 78-79

Unit 2 Lesson 3 The Sun

Mixing It Up

By Radiation – energy leaves the core in the form of electromagnetic waves

By Convection – energy (heat) is transferred by the circulation or movement of matter

http://www.physics.arizona.edu/~thews/reu/the_science_behind_it_all.html

http://outreach.atnf.csiro.au/education/senior/astrophysics/stellarevolution_mainsequence.html

Unit 2 Lesson 3 The Sun

Extreme to the Core

Unit 2 Lesson 4 The Terrestrial Planets

Terrestrial planets - the four small, dense, rocky planets that orbit closest to the sun

• astronomical unit (AU) - average distance between the sun & Earth, or approximately 150 million km.

http://physics.uoregon.edu/~jimbrau/astr121/Notes/Chapter6.html

Mercury

Period of Rotation-last almost 59 Earth days

Period of revolution-88 days

Temps range from -184˚C to 427˚C

Smallest planet with craters

Venus• Retrograde rotation

(clockwise)

• Rotation- 243 Earth days

• Revolution- 225 days• Temp- 465 ˚C; CO2

traps the sun’s energy• Thousands of

volcanoes & craters• Sulfuric acid rain

http://www.bobthealien.co.uk/venus.htm

Unit 2 Lesson 4 The Terrestrial Planets

Earth

Only planet that supports life

Liquid water, energy soursce

Atmosphere contains O2

Only planet divided into tectonic plates

Mars• Rotation- 24 h 37 min• Revolution- 1.88 Earth

years • Olympus Mons- largest

volcano/mtn in solar system

• Valles Marineris – longest canyon in solar system

• Thin CO2 atmosphere

Unit 2 Lesson 4 The Terrestrial Planets

http://en.wikipedia.org/wiki/Mars_Exploration_Rover

A Giant Among Giants!

•Gas giants have deep, massive gas atmospheres, made up mostly of hydrogen & helium. No surface to stand on. Large and cold.

http://www.daviddarling.info/encyclopedia/G/gasgiant.html

Unit 2 Lesson 5 The Gas Giant Planets

Jupiter

Rotates fastest – 9 h 55 min

Revolution– 11.86 Earth years

Great Red Spot 63 moons

Io Europa Callisto Ganymede

Saturn• Rotation- 10 h 39 min• Revolution- 29.5 years• Planetary ring system• Made of H+ & He• 60 moons

• Enceladus • Titan

Unit 2 Lesson 5 The Gas Giant Planets

http://www.gearthblog.com/blog/archives/2006/04/google_jupiter.html

Uranus

Rotation- 17 h 24 min Revolution-84 years Made of H+ & He Atmosphere of

methane Tilted on its side as it

orbits the sun 27 moons

Miranda

Neptune• Rotation-16 h 7 min• Revolution- 164.8

years• H+/He and methane • Great dark spot• 13 moons

• Triton-orbits opposite

Unit 2 Lesson 5 The Gas Giant Planets

http://www.bobthealien.co.uk/neptune.htm

Small Bodies in the Solar System

dwarf planets- celestial body that orbits the sun, is round because of its own gravity. Ceres (between Mars & Jupiter) Pluto Haumea Makemake Eris

Kuiper Belt- orbits just beyond Neptune

Kuiper belt object (KBO) -any of the minor bodies in the Kuiper belt. They are made of methane ice, ammonia ice, and water ice.

Comets

Comet -small body of ice, rock, & dust that follows a highly elliptical orbit around the sun.

Oort cloud - spherical region tht surrounds the solar system

http://janus.astro.umd.edu/front/pages/links/Comets2.html

On the Rocks

Asteroid – small, irregularly shaped, rocky object that orbits the sun. Most located in the asteroid belt between

the orbits of Mars and Jupiter Some are rich in carbon, others rocky with

cores or iron and nickel

Burned Out

Meteoroid -rocky body, ranging in size from that of a sand grain to that of a boulder, which travels through space.

Meteor -bright streak of light that results when a meteoroid burns up in Earth’s atmosphere.

Meteorite - a meteoroid that reaches Earth’s surface without burning up.