Unit 5: The Solar System Mr. Ross Brown Brooklyn School for Law and Technology

In this unit we will learn about: The primary components of the Solar System, each with unique properties The differences between Terrestrial, Jovian, and dwarf planets The ways astronomers measure masses and radii for bodies in the Solar System and calculate density How the planets formed The ways exoplanets are detected

What are the components of the Solar System? 16 November 2015 Do now: What are the different components of our Solar System?

The Sun

What are the components of the Solar System? The Sun Light and heat generated by nuclear fusion reactions Mass is 700 times all other bodies combined 71% Hydrogen, 27% Helium, and small amounts of all other elements

What are the components of the Solar System? The Terrestrial Planets (Earth-like) Mercury, Venus, Earth, Mars Small, rocky, thin or no atmosphere

What are the components of the Solar System? The Jovian Planets (Jupiter-like) Jupiter, Saturn, Uranus, Neptune Much larger, gaseous and liquid Deep, hydrogen rich atmospheres

What are the components of the Solar System? 17 November 2015 Do now: Beyond Neptune, what do we find that is still considered within our Solar System?

What are the components of the Solar System? Many other objects in our Solar System Pluto – Small, ice & rock, tilted orbit, crosses Neptune – Dwarf planet – Not so special; Eris is 2x as large, 68 AU – Plutoids

Pluto’s Orbit

Moons Our Moon Jupiter has 63, Saturn 61, Uranus 27 and Neptune 13. Mars has 2. Pluto has 4, Eris 1.

Asteroids Asteroids: rocky or metallic bodies Ceres is largest, 600 miles across Asteroid Belt is between Mars and Jupiter

Kuiper Belt 50 AU Similar to Asteroid Belt, but objects are made of ice Comets: about 10 km in diameter – Made of ice, grow tails as they near the Sun Further out, Oort Cloud – Perhaps 100,000 AU – Comets may originate here

Comets

Our Solar System

The Eames Brothers

Homework 16 November 2015 Why is Pluto not a planet? What are the three criteria that determine whether a body is a planet? Which criterion does Pluto fail to satisfy?

How do planets move about the Solar System? 23 November 2015 Do now: How thick is our Solar System (all the way out to Neptune) if you could look at it from the side?

How do planets move about the Solar System? Planets arranged along a line in the same plane Mercury tilts about 7° Counterclockwise orbits (View Earth from North Pole) About as thick as 3 CDs out to Neptune

Mercury’s Orbital Plane

How do planets move about the Solar System? Planets rotate as they orbit, counterclockwise Axes are generally perpendicular to orbit – Uranus tilts almost to orbital plane – Venus tilts so much it spins “backwards” Retrograde, but orbits with other planets

Other Objects Asteroids may be tilted but travel in same plane Comets travel in any direction – Could indicate Oort Cloud, rather than ring Moons behave similarly – Orbit planets along equator, with similar tilts – Large moons may have smaller moons

How are the Planets Spaced throughout the Solar System? Bode’s Law

In what ways are the Inner and Outer Planets Different? 24 November 2015 Do now: That’s it, in the line above. No, you’re smart, you can figure it out. The Aim is the Do Now. OK?

In what ways are the Inner and Outer Planets Different? How can we tell? – Spectragram – This can only tell us about atmosphere Density analysis (M/V) – Based on gravitational attraction to another body Moon, passing spacecraft We can know V=4πR 3 /3 R is radius, obtained from angular size and distance

In what ways are the Inner and Outer Planets Different? Compare density – Earth is 5.5 g/cm 3, silicate rock is 3, iron is 8 Inaccurate – Jovian planets on average 0.7 to 1.7g/cm 3

In what ways are the Inner and Outer Planets Different? Terrestrial Planet Interiors

In what ways are the Inner and Outer Planets Different? Jovian Planet Interiors

In what ways are the Inner and Outer Planets Different?

How do Planetary Systems Form? 30 November 2015 Do now: Describe our Solar System by listing basic details: shape, structure of planets, relationship to the Sun, age.

How do Planetary Systems Form? Our Solar System is: – Flat, with planets orbiting in same direction – 2 types of bodies: rocky inner planets close to the Sun, gaseous outer bodies further away – Outer planets similar in composition to the Sun; inner planets are like the Sun minus gases that only condense at low temperatures – Age of all Solar System bodies less than 4.6 billion years old.

How do Planetary Systems Form? Solar Nebula Theory – Solar System originated from a flat rotating disk of gas and dust – Outer part became planets, inner became the Sun

How do Planetary Systems Form? 4.6 BYA: Interstellar Cloud – Rotating aggregate of gas and dust

How do Planetary Systems Form? Solar Nebula – Interstellar cloud collapse into spinning disk with most mass in center

How do Planetary Systems Form? 2 December 2015 Do now: You have just met someone who isn’t in our class. Describe an interstellar cloud so your new friend understands why interstellar clouds are important.

How do Planetary Systems Form? Condensation of the Nebula – Gases cool  liquid  solid – Because of differences in condensation temperature, materials condense at different rates Iron, silicates, water

How do Planetary Systems Form?

Accretion: tiny particles stick together, forming bigger particles At a certain point, these accretions become large enough that we consider them planetesimals (small, planet-like bodies)

How do Planetary Systems Form? Planetesimals becoming planets

How do Planetary Systems Form? 3 December 2015 Do now: In what way(s) were the formation of the terrestrial planets and formation of the Jovian planets different?

How do Planetary Systems Form? Frost line: where Sun’s heat is reduced enough to have permitted ice to form during early planet formation. Roughly between Mars and Jupiter.

How do Planetary Systems Form? Planetesimal collisions: with each impact, heat is generated. Beyond 4 or 5 AU, planetesimal growth is more rapid; each had more material from which to grow and ices there added to silicates and iron.

How do Planetary Systems Form? As planets cool, remaining planetesimal impacts leave craters – Our Moon, Callisto, etc.

How do Planetary Systems Form? Some impacts were greater – Moon creation – Venus and Uranus’ rotational axes – Mercury’s missing crust

How do Planetary Systems Form? Some planetesimals didn’t become planets – Asteroid Belt – Oort Cloud – Kuiper Belt

Homework 4 December 2015 Use web resources and identify a recent news story in space exploration. Write a paragraph discussing the story and the goals of the mission. Please include one of the pictures associate with the story.

What is there beyond our Solar System? 7 December 2015 Do now: What do you think there is beyond our Solar System, even beyond the Oort Cloud? Are there planets with life?

What is there beyond our Solar System? Exoplanets: planets orbiting stars other than our Sun Why? – Because they’re there! – And, to learn about our own Solar System

What is there beyond our Solar System?

How do we detect exoplanets? – Gravity makes their star “wobble” – Limitation to this method: planet must be massive

What is there beyond our Solar System? How do we detect exoplanets? – Transit: exoplanet passes in front of its star – Limitation to this method: planet and star must align

What is there beyond our Solar System? What helps us detect these exoplanets? – Kepler space telescope