Sun, Earth, Moon - Los Angeles Mission College Sun • Earth • Moon Astronomy 1 —...

Astronomy 1 — Elementary Astronomy LA Mission College

Spring F2015

Sun, Earth, Moon

Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015

Cartoon of the Day

“From now on we live in a world where man has walked on the Moon. It's not a miracle; we just decided to go. “

-- Tom Hanks

Announcements

• HW Kepler, Gravity Light due

• CoC Star Party tomorrow

• Grading up to date!

Star Party

Join us for a

Friday,

OCT 16

7 – 9:30 p.m.Carl A Rasmussen AmphitheaterCollege of the Canyons Canyon Country Campus17200 Sierra Highway, Santa Clarita, CA 91351

COLLEGE OF THE CANYONS • Canyon Country Campus

STAR FORMATION: Light Beyond The VisiblePresented by Dr. Luisa RebullResearch Scientist, SSC and IRSA, IPAC, CaltechFeaturing: • Hands-on interactive demonstrations and activities

• COC student clubs and academic departments highlighting innovative approaches to understanding the science that governs the universe

• Gaze at the stars through a variety of telescopes

Food and beverages will be available for purchaseFor more information visit

www.canyons.edu/ccc • COL

LEGE OF THE CANYONS •

CANYON COUNTRY

Tallest TowerBuilding CompetitionSign-up online!

www.canyons.edu/Offices/CCC/Pages/StarParty.aspx

Last Class

• Midterm debrief

• Multi-wavelength Astronomy

• Intro to the Solar System

• LT Sun Size (completed, not debriefed)

This Class

• Grade Status

• Debrief LT Sun Size & do questions

• Sun

• Earth

• Moon

Spring F2015

Grade Status

Letter Midterm Course

A 9 13

B 7 18

C 14 8

D 12 4

Spring F2015

Debrief LT Sun Size

The Sun has a diameter of approximately 1.4 million kilometers. Roughly how many Earths would fit across the diameter of the Sun?

B. 100

C. 1000

D. 10,000

E. 1 million

Let’s Practice

The image at right shows a picture of the Sun. The dark spots located on this image are sunspots. How does the size of Earth compare to the size of the sunspot that is identified on the right side of the image of Sun?

A. Earth and the sunspot are about the same size.

B. The sunspot is much, much larger than Earth.

C. The sunspot is much, much smaller than Earth.

Sun Size – Instructor’s Guide 129

Third Edition

diameter by that of the Moon. Here is an opportunity to talk about proportional reasoning skills.

9) [ 220 orbital diameters ]

Since 110 Sun diameters would fit between Earth and the Sun and 2 orbital diameters of the Moon would fit across the Sun, then 220 Moon orbital diameters would fit between the Sun and Earth.

ADDITIONAL QUESTIONS 1) The image at right shows a picture of the Sun. The dark spots located on this image are

sunspots. How does the size of Earth compare to the size of the sunspot that is identified on the right side of the image of Sun?

a) Earth and the sunspot are about the

same size. b) The sunspot is much, much larger than

Earth. c) The sunspot is much, much smaller than

Earth.

2) Which statement do you think best represents the size comparison between the diameter of the Sun and the distance between the Moon and Earth? The Sun’s diameter is a) smaller than the distance between the Moon and Earth. b) approximately equal to the distance between the Moon and Earth. c) larger than the distance between the Moon and Earth.

3) If you were constructing a scale model of the solar system that used a Sun that was the size of a basketball (approximately 12 inches in diameter), which of the following lengths would most closely approximate the scaled distance between Earth and the Sun? a) 3 feet (length of an outstretched arm) b) 10 feet (height of a basketball goal) c) 100 feet (height of an 10 story building) d) 300 feet (length of a football field)

Which statement do you think best represents the size comparison between the diameter of the Sun and the distance between the Moon and Earth? The Sun’s diameter is

A. smaller than the distance between the Moon and Earth.

B. approximately equal to the distance between the Moon and Earth.

C. larger than the distance between the Moon and Earth.

If you were to construct a scale model of the solar system that used a 2 cm cherry to represent the Moon, how large of a ball would you need to represent the Sun?

A. 4cm

B. 30cm

C. 110 cm

D. 440 cm

E. 880 cm

Spring F2015

The Sun

THE SUN IS A STAR

What is a star?

• A sphere of hot gas

• mostly hydrogen & helium

• Interior hot enough to undergo nuclear fusion in core

• core above 107 K = 10 million K (18 million °F)

Why Stars Shine

• Visible Sun is a hot layer of gas

• about 5800 K (5525°C, 9980°F)

• not as hot as the center!

• Gives off light the same way that hot metal glows red, yellow or white

• Thermal radiation or blackbody

• This is why stars have different colors

Basic Data

• Fairly average star

• It rotates

• faster at the equator (25 days) than at the poles (31 days)

• Entirely gas: Hydrogen (80%) and Helium (19%)

• Central Temperature 15,000,000 K

• Surface Temperature 5800 K

http://www.kidsgeo.com/geography-for-kids/0003-how-big-is-the-earth.php

What Type of Star is the Sun?

• Main Sequence Star

• most stars spend most of their “life” on the Main Sequence

• energy source thermonuclear fusion

• H fusing to He in the core

What Type of Star is the Sun?

• Spectral Type G2

• Lifetime on Main Sequence 10 billion years

The structure of the Sun

• Core

• compact: center to about 25% radius

• 15 million K

• atoms completely ionized

• e- “blasted off”

• Where thermonuclear fusion is taking place.

• Radiative zone

• 0.25 - ~ 0.7 solar radii

• Energy from core transferred by EMR

• Convective zone

• above radiative zone

• Energy transferred to surface by convection

Convection

Bubbles of hot gas rising up

Cool gas sinking down

Let’s Practice

The Sun’s Luminosity comes primarily from

A. chemical burning

B. gravitational contraction

C. nuclear fusion

D. nuclear fission

The energy produced by the Sun is produced

A. in a very small region at the center of the Sun

B. Uniformly throughout the Sun

C. At the surface of the Sun

THE OUTER LAYERS OF THE SUN

• Photosphere

• Visible surface of the Sun

• Apparently smooth layer of gas

• 500 km thick

• 5800 K

• Sunspots

Granulation

• Up close, photosphere has a mottled appearance (granulation) due to convection cells.

• These cells form and fade and shift on a time scale of tens of minutes.

Sunspots

• well-defined surface areas that appear darker than their surroundings because of lower temperatures.

• Associated with sun’s magnetic field

• convection is inhibited by strong magnetic fields, reducing energy transport from the hot interior to the surface http://

• Chromosphere

• Atmospheric layer above the photosphere.

• 1000x fainter than the photosphere, but hotter!

• Chromosphere

• Pink color during a total eclipse.

• Filaments (dark regions) & Spicules/prominences (jets).

Solar Prominence

Let’s Practice

Sunspots appear dark because

A. They are holes in the photosphere allowing a view of deeper layers

B. Are large opaque structures that block the light from the interior

C. Are slightly cooler than the surrounding areas, appearing dimmer

D. Are burning holes in your retina

THE CORONA, SOLAR WIND AND SOLAR WEATHER

• Corona

• Outermost atmospheric layer.

• Extending outwards 20 times the Sun’s radius.

• Heated by magnetic field interactions.

• solar wind • 300 - 1000 km/s

• Loses 10 million tons/yr

http://antwrp.gsfc.nasa.gov/apod/ap080920.html

Solar Weather

• In addition to sunspots, solar activity results in

• Solar flares

• Aurora Borealis

• Coronal Mass Ejections

• Geomagnetic Storms

• http://spaceweather.com/, http://www.swpc.noaa.gov/

(Ultraviolet images)

Aurora Borealis

Solar Weather and Humans

• Solar flares

• really refer to increased brightness

• Coronal Mass Ejection

• Interferes with Satellites

• Geomagnetic Storms

• In rare cases causes power grid issues

FATE OF THE SUN

Endgame for our Sun

• A star’s fate is pretty much determined at the moment of it’s “birth” by its mass

• and the company it keeps

• High mass stars, ~ 8x Sun, explode

• supernovae

• Low mass stars like the Sun have a different fate

• Sun does NOT!!!!! “go supernova”

Main Sequence to Red Giant

• After the core becomes depleted of H, the Sun will become a red giant

• A much larger, cooler star

• Earth, in all likelihood, gets swallowed up

Ar#sts concept of the Sun as a red giant:

Image: ESA

He core

H burning shell

Red Giant to White Dwarf

• Eventually the red giant exhausts the H in its shell

• throws off up to half its mass

• “planetary nebula”

Spitzer Space Telescope Image of a PN the Helix Nebula

Fading away...

• Core becomes a white dwarf

• Squeezed into size of Earth

• Maximally compressed into a degenerate gas

• In isolation, very slowly cools and fade away

Artist’s conceptImage ESA/NASA

Let’s Practice

The Sun will ultimately

A. Go Supernova

B. Become a white dwarf

C. Become a black hole

Which of the following are the most potentially damaging consequences of solar activity

A. Solar flares & Aurora Borealis

B. Coronal Mass Ejections & Geomagnetic storms

C. Promenences and Spicules

Spring F2015

The Earth as a Planet

Comparison of the “Terrestrial” Planets

The “Habitable Zone”

• In astronomy and astrobiology, the habitable zone is the region around a star where a planet with sufficient atmospheric pressure can maintain liquid water on its surface.

www.astrobio.net

Earth’s Statistics

• Equatorial Diameter = 12,756 km • Mass = 5.98 x 1024 kg • av. density = 5.5 g/cc • surface T = -50°C to +50°C • a = 1.00 AU • P = 1.00 year • e = 0.0167

Earth’s Uniqueness

• Every major process on any rocky world in our solar system is represented in some form on Earth.

• Unique in 2 important ways

1. Surface water (75% of the surface is water)

• No other SS body has surface water currently

2. Life

• No other SS body has been found to have life. Yet.

Earth’s Early History

• Formed 4.6 billion years (4.6 x 109) ago from the inner solar nebula.

• 4 Stages of Evolution: • Differentiation

• Heavy Bombardment: Cratering

• Flooding

• Slow Surface Evolution

Earth’s Structure — Core

• Hot as the Sun’s surface (~6000 K)

• Solid inner core

• liquid core surrounding it

• Source of Earth’s magnetic field

• Dynamo effect

Earth’s Structure — Mantle

• Solid (“plastic”) Mantle

• As in deformable, not as in manmade

Earth’s Structure — Crust

• Solid

• Thicker under land (60 km)

• thinner under oceans (10 km)

• Brittle: Broken into tectonic plates

• only terrestrial planet with plate tectonics

Earth’s Magnetic Field

• Is Useful

• Likely helps birds & fish know where N and S are for migration

• Compasses

• Most importantly, it protects us from the solar wind

• which would otherwise slowly strip the Earth’s atmosphere away...which would NOT be good!

• Is generated by the dynamo effect

Magnetic Field via Dynamo Effect

• 2 Key components

• Liquid conductor

• Rotation

• Earth

• ample liquid iron outer core, plus

• fairly brisk 24 hr rotation, yields

• strong magnetic field image from: http://www.abc.net.au

The Core and the Dynamo

• Earth’s core consists mostly of iron + nickel

• high electrical conductivity.

• A conductor in motion creates a magnetic field

• The liquid core convects and the Earth Rotates

• Results in a dipole field

PLATE TECTONICS

Plate Tectonics

• Plates are moved by convective motion in the mantle

• hot material rises and cools, cool material sinks

Earth’s Tectonic History

LET’S PRACTICE

If the Earth’s rotation were to slow down drastically which of the following would most likely happen?

A. Runaway Greenhouse effect, leading to unsurvivable surface temperatures

B. Diminishment of Earth’s magnetic field, leading to loss of protection from the solar wind

C. Diminishment of atmospheric friction, leading to dramatic cooling of the surface

D. Diminishment of gravitational force, leading to loss of the Moon.

Plate tectonics exists on Earth because _____.

A. convection in the mantle causes motion

B. the crust is thin and broken into pieces

C. both of these

D. neither of these

EARTH’S TIMELINE

History of Geological Activity

Earth’s Atmosphere

• 76% Nitrogen, 23% Oxygen, 1.3% Argon & a smattering of other stuff

• (water and carbon dioxide included).

• Ozone (O3) protects the surface from UV radiation (26 km up).

• Carbon Dioxide i s a “greenhouse gas:” it is transparent to visible light, but opaque to infrared light

Evolution of Atmosphere

• Primordial Atmosphere

• Whatever was outgassed by the geologic activity (volcanoes) of ~4 billions years ago.

• carbon dioxide (CO2), nitrogen, water vapor.

• The CO2 levels decreased

• As Earth cooled, water vapor condensed. Oceans formed!

• The oceans absorbed CO2 (CO2 is soluble in water… think carbonated drinks!)

• The CO2 reacted with other elements in the water

Evolution of Atmosphere

• O2 levels increased

• Initially, any oxygen present reacted with minerals to form iron oxide, etc…

• The rise of oxygen levels in the Earth’s atmosphere is tied to life.

• Specifically photosynthesis

• evolved 2.7 - 2.4 billion years ago

• picked up when the oceans developed plant life 2-2.5 billion years ago

• Oxygen exists because of life, not vice versa!

Where Water Came From

• Not completely well understood. Several hypotheses:

• Older hypothesis: Primordial content and Vulcanism

• When a volcano erupts, 50-80 % of the gas is water vapor.

• Newer understanding: Primordial outgassing

• Earth formed so rapidly that it was substantially heated by the impacts of infalling material, as well as by radioactive decay.

• Molten surface -> continuous outgassing

• straight to the volcanic “ secondary atmosphere” without a hydrogen- rich primeval atmosphere.

• Some of the water may have arrived late in the formation as a bombardment of volatile-rich planetesimals

• studies of Comet LINEAR, which broke up in 1999 as it passed near the sun, support this

Spring F2015

The Moon

Importance of the Moon

• Moderates wobble of Earth’s axis

• stabilizes climate

• Tides

• Cultural and Historical importance

• Only place aside from Earth we have visited in person

• Lunar Ranging

Image Credit: NASA

Galileo Image taken on way to Outer Solar

System

Apollo 16, Image Credit: NASA

CHARACTERISTICS OF THE MOON

Moon Earth

• Equatorial Diameter = 3476 km

• mass = 7.35 x 1022 kg

• average density = 3.4 g/cc

• surface temp = -170°oC to

+130°C

• a = 384,400 km (from Earth!)

• P = 29.5 days (around Earth!)

• e = 0.055

• Equatorial Diameter = 12,756

• mass = 5.98 x 1024 kg

• average density = 5.5 g/cc

• surface temp = -50°C to +50°C

• a = 1.00 AU

• P = 1.00 y

• e = 0.0167

Key Characteristics of the Moon

• No magnetic field

• Small core, no iron

• No atmosphere

• Too small & hot to hold onto gases

• gas molecules readily reach escape velocity!

• Very dry

• no sedimentary rock

• some ice may exist under the surface

Oblique View of the Lunar Crater Tycho

Credit: NASA/GSFC/Arizona State University

The Moon: The View from Earth

• Tidally coupled to the earth

• rotation = revolution

• always see same side

• Heavily cratered highlands

• Smoother, darker lowlands

• maria (“seas”)

• flooded by lava

• Cool

Farside from LRO

Credit: NASA/GSFC/Arizona State University

Nearside from LRO

Lunar Craters

• Numerous!

• >300,000

• Named after people: scholars, scientists, explorers

• Typical crater morphology Tycho

CopernicusKepler

Aristarchus

MareTranquillitatis

MareSerenitatis

MareCrisium

MareImbrium

Oceanus

Procellarum

MareNubium

Lunar Maria

• large, dark, basaltic plains

• lava flooded low-lying areas

• more prevalent on near side

• 1.2-4.2 billion y.o.

• radiometric dating

• crater counting

CopernicusKepler

Aristarchus

MareTranquillitatis

MareSerenitatis

MareCrisium

MareImbrium

Oceanus

Procellarum

MareNubium

LET’S PRACTICE

There is very little atmosphere on the Moon because

A. dry rocks on the moon absorb gases as soon as they are created.

B. it was blown away by meteor bombardment.

C. its low mass and high temperature allowed most gases to escape.

D. the gravitational tidal forces from the Earth stripped it away.

The Moon

A. always points the same face towards the Sun.

B. does not rotate.

C. rotates at the same rate as the Earth rotates -- once per day.

D. rotates at the same rate as it revolves around Earth -- once per month.

LUNAR EXPLORATION

History of Lunar Exploration

• 1st visited by the USSR's Luna 1 and Luna 2 in 1959.

• These were followed by a number of U.S. and Soviet robotic spacecraft. US sent:

• Rangers (1961-1965) were impact probes,

• Lunar Orbiters (1966-1967) mapped the surface

• Surveyors (1966-1968) were soft landers.

• Apollo program -- Men on the Moon

• Lunar exploration resumed in the 1990s

• Clementine & Lunar Prospector

Manned Lunar Exploration

• May 25, 1961 -- President John Kennedy committed the United States to landing a human being on the moon by 1970.

• Vehicle hefty enough to get to moon would be difficult to land: Two-module design with “disposable” lander • Command module

• The lunar landing module ( LM )

• The first human- piloted lunar landing was made July 20, 1969.

• July 1969 -- December 1972,: • 12 people reached the lunar surface

• collected 380 kg ( 840 lb) of rocks and soil

Apollo Landing Sites

• First Apollo missions landed on safe, smooth terrain.

• Apollo 11: Mare Tranquilitatis; lunar lowlands

• Later missions explored more varied terrains.

• Apollo 17: Taurus-Littrow; lunar highlands

The Apollo Missions

• Hoax Believers, please check out Mr. “Bad Astronomy” Phil Platt’s extensive rebuttal:

• http://www.badastronomy.com/bad/tv/foxapollo.html

• And this filmmaker’s assessment of why faking it would have been harder than making it

• http://www.space.com/19531-moon-landings-faked-filmmaker-says-not-video.html

Moon Landing Remastered

• http://video.nationalgeographic.com/video/news/space-technology-news/1969-moonlanding-vin/

Moon Rocks

• Igneous (solidified lava)

• No sedimentary rock

Vesicular (= containing holes

from gas bubbles in the lava) basalts, typical of

dark rocks found in maria

Breccias (= fragments of different types of rock

cemented together), also containing anorthosites (= bright, low-density rocks

typical of highlands)

Older rocks become pitted

with small micrometeorite

craters.

LUNAR FORMATION

Must Explain

• Similar oxygen isotopic composition to Earth

• But different chemical composition -- low density

• No magnetic field

• All igneous rock

• Same age as Earth

• Maria and Highlands

Moon formation

• Fission Hypothesis

• Earth broke in two (if it were spinning quickly enough)

• Condensation Hypothesis

• Earth & Moon formed as a double planet system

• Capture Hypothesis

• Earth gravitationally captured a pre-existing body

• Large-impact hypothesis

• Early earth and moon formed from the glancing collision of two protoplanets

• Resulting large body became the earth and ejected debris formed the moon

• Could have caused Earth’s 23° tilt

Large Impact Hypothesis

• Impacting body about the size of Mars — Theia

• Impact heated material enough to melt it

• consistent with “sea of magma”

• Collision not head-on

• Large angular momentum of Earth-moon system

• Collision after differentiation of Earth’s interior

• Different chemical compositions of Earth and moon

• Earth absorbed iron core of impactor

• Molten remnant material coalesced into Moon

LET’S PRACTICE

Which proposed explanation for the Moon’s origin was ruled out when the Apollo mission revealed similar abundances of isotopes of oxygen in lunar rock as on Earth?

A. that the Moon broke off from the Earth

B. that the Moon and Earth formed together out of the same material

C. that the Moon was a passing body that was gravitationally captured by the Earth

D. that the Moon was formed when a large object impacted the proto-Earth

WRAP-UP

Topic for Next Class

• Mercury, Venus, Mars

• Greenhouse effect

Reading Assignment

• Astro: 7

• Astropedia: 8

Homework

• No new HW yet

Sun, Earth, Moon - Los Angeles Mission College Sun • Earth • Moon Astronomy 1 —...

Documents

PHY134 Introductory Astronomy The Moon and Planets 1

The astronomy of the Bible. An elementary commentary on

Welcome to PPT Astronomy Sun, moon, tides

ASTRONOMY FROM THE MOON - Lunar University …lunar.colorado.edu/~jaburns/publicfiles/tiny/files/astronomy.moon.pdf · ASTRONOMY FROM THE MOON Jack Burns Center for Astrophysics and

Our Moon & Moon Exploration Astronomy 1. Vocabulary New moon Waxing phase Full Moon Waning phase Solar eclipse Lunar eclipse Tides Craters Marias Highlands

The Moon - FatCowvincentlloyd.fatcow.com/Public/23Moon.pdf · Universe 2 Astronomy 20 4 The Moon Astronomy 20 5 The Moon Harvest Moon Nearest full moon to the Sept. equinox The Moon

X-ray Astronomy From Moon

Astronomy Stars, Galaxies, and the Universe. What is Astronomy? Astronomy is the study of the moon, stars, and other object in space Astronomy is the

ASTRONOMY 195: OBSERVATIONAL ASTRONOMY · 2017. 12. 14. · ASTRONOMY 195: OBSERVATIONAL ASTRONOMY Homework #2: NAKED EYE OBSERVATIONS OF THE MOON Due November 13, 2014 Part I: PLOTTING

The Moon Astronomy 311 Professor Lee Carkner Lecture 13

Elementary Astronomy - MavDISKmavdisk.mnsu.edu/wp5884kt/ea/ea.pdf · Pierce: Elementary Astronomy Chapter 1: Introduction 5. ... All students should develop an understanding of objects

The Moon in Modern Astronomy

Lab 2: Phases of the Moon - Physics & Astronomy

PHYS 101: Elementary Astronomy

Ancient Greek Astronomy: The Distance to the Moon and · PDF fileAncient Greek Astronomy: The Distance to the Moon and the Sun Denis Erkal

Phases of the Moon Astronomy Unit - College of Arts and Sciences

Moon Elementary School

Origin of the Moon - Institute of Astronomy,wyatt/poa_201415_originofmoon.pdf · Origin of the Moon The Earth-Moon system The Moon orbits the Earth at a moon = 385,000 km ... Tides

Astronomy Unit 3 Artificial Satellites Natural Satellites Our Moon Orbit of our Moon Surface Features of our Moon Origin of our Moon

Astronomy- Motion, eclipses, tides, moon