Astronomy C12, Earth & Planetary Science C12, Letters & Science C70

The Planets

Prof. Michael Manga Prof. Geoff Marcy QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.

Dione in front of Saturn and its Ring

Tu, Th 11-12:30 am 100 Lewis

Professors

Geoff Marcy 417 Campbell Hall

[email protected]

Michael Manga 173 McCone Hall [email protected]

Departments of Astronomy, Earth & Planetary Science

GSIs:

Linda Strubbe Nicholas McConnell Arianna Gleason Karrie Weaver linda@astron nmcc@astro [email protected]

karrie@eps

8 Discussion Sections

1 hr each (Start

Next

Review, Clarification, Homework Help Sign up for Section on Telebears Week)

Text:

The Solar System: The Cosmic Perspective

Bennett et al. (2006) 4th Edition (not 3rd)

Web Site on bspace: http://bspace.berkeley.edu

• Syllabus, Schedule & Lecture Figures (no animation) • Assignments: Reading,

Homework

, Observing Project • Class Information

Homework: 50% of your grade

• • • 12 assignments during semester Most questions from your text The Astronomy Learning Center (TALC): • 264 Evans Time: TBA • • • First homework set available Friday Due by Friday Feb 2 Turn in HW by Friday at noon: • Box labeled Astro/EPS 12 in the basement of Campbell Hall.

Homework:

• You are encouraged to work together, but MUST turn in your own work, in your own words • The graders can recognize copying, and answers found with Google • Refer to the Berkeley Code of Student conduct if you are unclear about what constitutes cheating or plagiarism

Announcements

• No discussion sections this week • Read Ch 1 of the text this week; Ch 2 by next • First Homework Assignment: posted Friday.

•No Clickers

Last Time : : QuickTime™ and a TIFF (Unc ompressed) decompres sor are needed to see this picture.

The Solar System

Inner Solar System Outer Solar System

Overview

Our place in the Universe

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T IF are F (U n ee nc de om d t Qu Quic kTime™ and a TIFF (Unc ompres sed) dec ompres sor are needed to see t his pic ture.

pi ctu m re .

d a pre ss or 13 billion Light Years

The Solar System:

Sun and 8 Planets Moons, Asteroids, Comets, and Dust QuickTime™ and a YUV420 codec decompressor are needed to see this picture.

Milky Way Galaxy

Photo taken from Earth 200 Billion Stars You Are Here QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture.

Our Sun and the stars orbit around the center of the Milky Way Galaxy every 230 million years.

Our Sun moves relative to the other stars in the local Solar neighborhood.

Spiral Galaxies

Elliptical Galaxies

Irregular Galaxies

The ``Local Group”

100,000 Light Years

of Galaxies

The Galactic Neighborhood

The ``Local Group’’ of Galaxies

And outward…

10 Million Light Years

The Universe:

All matter and energy > 100 Billion Galaxies

Astronomical Numbers

Best to use Exponential Notation 10 3 10 6 10 9 = 1000 Thousand = 1,000,000 Million = 1,000,000,000 Billion Also: 10 –3 = 1/1000 = 0.001

Exponential notation is handy: 10 N x 10 M = 10 (N+M) Example:

10 3

thousand

x 10 6

million

= 10 9

billion

How many stars in our visible Universe?

a) 10 6 (1 million) b) 10 12 (1 million million c) 10 18 (1 billion billion) d) 10 22 e) infinite

Federal Debt QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture.

02 03 04 05 Debt Total The National Debt is

$7.6 Trillion = $7.6 x 10 12

U.S. Population = 300 x 10 6 Calculate Your Debt:

$7.6 x 10 12 / 3 x 10 8 $2.5 x 10 4 = $25,000 per person

Distance

,

time

and

number

: Scientific notation: Radius of our Galaxy: 6,000,000,000,000,000,000 m = 6 x 10 18 m Radius of a Hydrogen atom: 0.00000000005 m = 0.5 x 10 –10 m Time for one vibration of an oxygen molecule, O 2 : 0.00000000000001

s = 1 x 10 –14 s Age of the Universe: 470,000,000,000,000,000 s = 4.7 x 10 17 s = 14 billion years

SI (Systeme International) Units

Base units: 1 meter ( m ) length~ 3.3 ft 1 kilogram ( kg ) mass ~ 2.2 lb 1 second ( s ) time



MKS System of units and measure

SI (Systeme International) Units Base units: 1 meter ( m ) length 1 kilogram ( kg ) mass 1 second ( s ) time



MKS System of units and measure Sometimes easier to derive other units from these: km, g, ms, µs, … km = 10 3 m

kilo

g = 10 -3 kg

kilo

ms = 10 -3 s µs = 10 -6 s

milli micro

UNITS ARE IMPORTANT!!!

Mars Climate Orbiter: Launch: 11 Dec. 1998 Orbit insertion: 23 Sep. 1999 Followed by: Loss of Communication WHY?

Failed to convert from English units (inches, feet, pounds) to Metric units (MKS)

$Billion error

Light takes time to travel: 3 x 10 8 m/sec = 3 x 10 5 km/sec = 0.3 m/ns

(1 ns = 10 -9 s) Light Year = 9 trillion km = 6 trillion miles Light Hour Light Minutes are unit of Distance: How far Light Travels in that interval of time 1 light second = 3 x 10 5 km 1 light ns = 30 cm ≈ 1 foot

Driving the Mars Exploration Rovers (MER)

• How long does it take to communicate with the rovers?

NASA/JPL/Cornell

How long does it take for radio waves (light) to reach Mars?

a) Less than 1 second b) 10 seconds c) 5 minutes d) 1 day e) 1 year

How to deal with very large & small numbers

•Develop a useful arithmetic Exponential notation; convert between units •Visualize using a sequence of images (movie) Use different sequences •Visualize by way of a scale model Try different models

A Scaled Model of the Solar System 10 Billion x Smaller Sun’s diameter: 14 x 10 10 cm (~ 10 6 miles) Scale 10 10 : 14 cm

10 10 Scaled Down “Sun” QuickTime™ and a TIF F ( Uncompressed) decompressor are needed to see this picture.

14cm

Earth diameter: 1.3 x 10 4 km 0.13 cm Jupiter’s diameter: 150,000 km 1.5 cm Earth’s distance from Sun: 1 “Astronomical Unit” = 1 “AU”

1 AU ?? cm

= 1.5 x 10 8 km

a) 0.15 cm b) c) 1.5 cm 15 cm d) 150 cm e) 1500 cm Ans:

1500 cm = 15 meters

How large is the Solar System?

• Let’s view it

to scale

– say the Sun is the size of a large grapefruit, 15 cm (6 inches) - then:

Planet dist (AU) Scaled dist (m) Where?

Mercury 0.4 6 6 rows back Venus 0.7 10 10 rows Earth 1.0 15 Mars 1.5 22 15 rows 22 rows Jupiter 5 75 3/4 football field away Saturn 10 150 1.5 football field away Uranus 20 300 Sproul Plaza Neptune 30 450 Bancroft Ave Pluto 50 750 Durant Ave Oort Cloud 50,000 5 x 10 5 Oakland

Neptune o You Are Here: Earth’s Orbit .

Uranus o Saturn o Jupiter o

How Far is the Nearest Star?

Alpha Centauri

d = 4 light years = 4 x 10 16 m Scales to: 4 x 10 6 m (~ 3000 mi) Grapefruit-sized Sun in Berkeley Nearest Grapefruit: In Washington D.C.

Powers of Ten “Cosmic Voyage”

The Movie

How old is the Universe?

• The Cosmic Calendar – if the entire age of the Universe were one calendar year – one month would be approximately 1 billion real years

Key Issues So Far:

• What does our solar system look like when viewed to scale?

• How far away are the stars?

• How do human time scales compare to the age of the Universe?

TODAY’S LECTURE

•

Solar System Resides within our Milky Way Galaxy

•

Ranges of distances and time are huge.

•

Exponential notation and models are a real Help!

•

Distance Units: 1 Astronomical Unit (AU) = Earth - Sun Distance = 93 million miles = 150 million km

What is the origin of the Universe?

• The two simplest atoms (H and He) were created during the

Big Bang

.

• More complex atoms were created in stars.

• When the star dies, chemical elements are expelled into space…. to form new stars and planets!

Most of the atoms in our bodies were created in the core of a star!

The Universe in a Day

Look at the entire history of the Universe as though it took place in a single day. The present is at the stroke of midnight at the end of that day. Since it is about 13.5 billion years old, each hour will be ~0.5 billion years. A million years takes only a little over 7 seconds.

The Big Bang (a dense, hot explosion) and the formation of H and He all take place in the first nanosecond. The Universe becomes transparent in about 2 seconds. The first stars and galaxies appear after about 2am.

O ur Galaxy forms at 4am. Generations of stars are born and die.

The Universe in a Day

The Solar System does not form until 3pm. The first life (bacterial) appears on the Earth by 4pm. Our atmosphere begins to have free oxygen at 7 or 8 pm, and this promotes the development of creatures which can move more aggressively and eat each other. Life does not begin to take on complex forms (multicellular) until 10:45pm. It moves onto land at 11:10. The dinosaurs appear at about 11:40, and become extinct at 11:52. Pre-human primates appear at around 14 seconds before midnight, and all of recorded history occurs in the last 70 milliseconds.

Looking to the future, we can expect the Universe of stars to go on for at least another millennium (using the same time compression factor). After that, there are other ages of the Universe (not dominated by stars), which grow colder and more bizarre, and take place on astronomical timescales…

The Earth orbits around the Sun once every year! The Earth’s axis is tilted by 23.5

º!

What is the Earth’s velocity about the Sun?

Radius of Orbit

( 1 AU )

: 150 x 10 6 km Circumference: 2 π x radius Distance around the Sun that the Earth travels: 2 π x (1.5 x 10 8 km) = 9 x 10 11 m Earth orbits the Sun once a year: 1 yr = 3 x 10 7 s Velocity = Distance/Time = 9 x 10 11 m / 3 x 10 7 s = 3 x 10 4 m/s = 30 km/s 110,000 km/hr or 75,000 miles/hr!

A Universe in motion

• Contrary to our perception, we are not “sitting still.” • We are moving with the Earth.

– and not just in one direction The Earth rotates around it’s axis once every day!

Looking back in time

• Light, although fast, travels at a finite speed.

• It takes: – 8 minutes to reach us from the Sun – 8 years to reach us from Sirius (8 light-years away) – 1,500 years to reach us from the Orion Nebula • The farther out we look into the Universe, the farther back in time we see!

The Milky Way moves with the expansion of the Universe!

• Mostly all galaxies appear to be moving away from us.

• The farther away they are, the faster they are moving.

– Just like raisins in a raisin cake; they all move apart from each other as the dough (space itself) expands.