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Introduction to Oceanography• Lecture 2: Oceans on Earth and Elsewhere

Magma degassing at Halemaumau Crater, Kilauea, HawaiiApril 2008, Mila Zinkova, wikimedia, CC A S-A 3.0

Introduction to Oceanography

1. Attend Your Lab Section!

Recurring Slope Lineae

(flowing water?) in Newton Crater, Mars

(NASA/JPL-Caltech/U. Arizona image; Public Domain)

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Scientific Units: The S.I. System• SI units:

Length: meters, mTime: seconds, sMass: kilogram, kgTemperature: ºC (ºK)

Stilfehler, Wikimedia, Public Domain

Photo by 1-1111, Wikimedia, Creative Commons A. S.-A. 3.0

K20 kilogram, NIST.govimage,

Public Domain

Racklever, Wikimedia, Creative Commons A. S.-A. 3.0

Temperature: Celsius• oC are an international unit of temperature

(technically a derived SI Unit)

Water Melts BoilsoF 32 212oC 0 100

Celsius -> Fahrenheit: TF = 9/5 TC + 32o FFahrenheit -> Celsius:TC = 5/9 (TF - 32o F)The base SI unit of Temp is ºK, TK = TC+273.15º

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Using units in calculations

• Mathematical rules for working with quantities with units

– Can only add or subtract quantities with the

same units

• Must convert to same units when necessary

– Units are carried along in multiplication and division

Unit Conversions

• Examples:– Simple Case:

• The Earth’s core is ~3500 km thick.The Earth’s mantle is ~2900 km thick.

•Together the Earth’s core and mantle are:

3500 km + 2900 km = 6400 km thick. (same units)

–More difficult:•The average ocean depth is 3.8 km.

•Sunlight penetrates about 200 m into the ocean.

•How much of the ocean is dark?

-- need to convert so that units are the same:3.8 km = 3800 m.

3800 m – 200 m = 3600 m.

USGS, presumed Public Domain

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Multiplying or dividing UnitsWhen two quantities are multiplied or

divided, the units are also multiplied or divided, becoming compound

units:

Salinity of 1 liter of seawater

containing 35 grams of dissolved salt: 35 g = 35 g/liter

1 liter•Speed of a tsunami wave that crosses 1000 km of ocean in 1.5 hours:

(1000 km)/(1.5 hours) = 667 km/hour

FAST!

Hannes Grobe, wikimedia, CC A S-A 2.5

QUESTIONS?

Water-bearing “Fountains” on Saturn’s moon Enceladus, Cassini Spacecraft NASA/JPL/SSI, Public Domain

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Scientific Notation• Compact form for writing very large or

very small numbers

• Powers of 10:

Scientific Notation

• Negative powers of 10:

Nice web demonstrations of powers of 10:

http://micro.magnet.fsu.edu/primer/java/scienceopticsu/powersof10/

http://www.wordwizz.com/pages/10exp-35.htm

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Scientific Notation

• Examples: How many seconds per year?

365 days/year x 24 hours/day x 60 minutes/hour x 60 seconds/minute

= 31,536,000 seconds/year

31,536,000 = 3.1536 x 10,000,000

31,536,000 = 3.1536 x 107

31,536,000 = 3.1536 x 107

0.001221 = 1.221 x 10–3

Scientific Notation

• Examples:

Coefficient Exponent

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Scientific Notation

• Addition: Convert numbers to same power of 10, then add coefficients:

Scientific Notation

• Subtraction: Convert numbers to same power of 10, then subtract coefficients:

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Scientific Notation

• Multiplication: Just multiply coefficients and add exponents:

Scientific Notation

• Division: Just divide coefficients and subtract exponents:

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Ocean world(s?)The Earth & Planets

• Earth in space

• Gross structure of the Earth

– Crust

– Mantle

– Core

• Origins of Earth’s water

• Shapes of the ocean basins

Saturn’s moon Titan, Cassini Spacecraft NASA/JPL/SSI, Public Domain

QUESTIONS?

The Solar System (not to scale), art by Omnidoom 999, CCASA 3.0 Unported, https://commons.wikimedia.org/wiki/File:Sonnensystem_Navigationsleiste.png

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Our Solar System (not to scale!)

• The Sun

• Planetsand Moons

• Dwarf Planets,Minor Planets,Meteoroids, Comets

Image by Harman Smith and Laura Generosa, NASA/JPL, Public Domain

How do solar systems form?

Large clouds of gas between stars can collapse under their own gravity,

especially when disturbed, for instance by a supernova explosion

The collapse is a runaway

process, leading to high-density clumps that become stars and solar systems

~ 1.2 light years82,500 times the

Earth-Sun distance

1.1 x 1016 meters

Computer simulation by Matthew Bate, UK Astrophysical Fluids Facility, Non-profit use allowed, http://www.ukaff.ac.uk/starcluster/

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Birth of a solar system

After collapse, each new star may have an associated disc of

leftover material trapped in its

gravity. Some condenses to make planets.

Artists image. ESO/L. Calçada, C.C. A. 3.0 Unported, http://www.eso.org/public/images/eso0942a/

We can see new solar systems forming today!

Proplyd (protoplanetary disk) around star HL Tau

ALMA Radio Telescope Array image [ALMA (NRAO/ESO/NAOJ); C. Brogan, B. Saxton (NRAO/AUI/NSF)], Creative Commons License CC BY 4.0,

http://www.eso.org/public/images/eso1436a/ http://www.eso.org/public/archives/images/large/eso1436a.jpg

Our Solar System at the same scale

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More proplyds in the Orion NebulaHubble Space Telescope image, Public Domain, http://apod.nasa.gov/apod/ap091222.html

Hubble Space Telescope image, Public Domain, http://hubblesite.org/newscenter/archive/releases/1994/

24/image/b/

Other Planetary Bodies with Oceans?• Probably water oceans on

Europa, Ganymede & Callisto (moons of Jupiter)

Enceladus and Titan (moons of Saturn)

Subsurface briny oceans with solid icy “crust” -- thin

• Lakes on Titan (largest moon of Saturn)

– Liquid methane/hydrocarbon pools, not water!

• Ancient Mars?

– Flood channels & deep,flat N. hemisphere

• Definitely Earth

Hubble Telescope image, NASA/ESA/HST/STSCI, Public Domain

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“All these worlds are yours, except Europa. Attempt no landings there.” (2010: Odyssey Two, Arthur C. Clarke)

Jupiter’s moonEuropa, Galileo

Spacecraft image, NASA Public Domain

What Planetary Bodies have Oceans?Europa – a moon of Jupiter.

Bright, icy surface lacking craters – evidence of recent resurfacing.

Geophysical andmagnetic evidence of saltyliquid water at depth.

Salt water isalso likely present

at depth inside Ganymede, another moon of Jupiter.

NASA/JPL-Caltech image and art. Public Domainhttp://photojournal.jpl.nasa.gov/figures/PIA19656

_fig1.jpg

What Planetary Bodies have Oceans?Enceladus – a moon of

Saturn.Also has few craters

It is spewing water into space!

Geysers may tap deep ocean.

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What Planetary Bodies have Oceans?

Titan -- largest moon of Saturn.

Persistent radar “dark spots” near North & South Poles

Consistent with liquid methane/ethane

+South Pole

Images fromCassini Spacecraft (NASA),

Public Domain

What Planetary Bodies have Oceans?

• Early Mars: Northern oceans?• Water ice found in soil!• Hydrous salts over “seeps”

NASA Images, Public Domain

MOLA Digital Altimetry

Gusev Crater (Spirit)

Meridiani Planum(Opportunity)

Gale Crater(Curiosity)

(Phoenix)

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Liquid water on Mars today?

Seasonal streaking inside Newton Crater, MarsMcEwen et al. 2011 (Science); Ohja et al. 2015 (Nature Geoscience). Images NASA/JPL-Caltech/Univ. of Arizona

http://www.nasa.gov/mission_pages/MRO/multimedia/gallery/gallery-index.html

Chevrier et al. 2009

Extrasolar Planets• Evidence for planets around other stars

– 3671 confirmed, 616 systems with multiple planets, as of Sept. 7, 2017 (+many unconfirmed, mostly from Kepler spacecraft)

Image of HR8799, a solar system129 light years away from Earth.

By Ben Zuckerman, UCLAusing the Keck Observatory telescope

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Animation by Ethan Kruse, U. Washington, showing planetary systems discovered by the Kepler mission as of Nov. 24 2015 ( > 3,000 planets) Permission for use in presentations with citation

granted explicitly by the author. http://staff.washington.edu/eakruse/dataviz.php

Most planets found so far are closer to their stars than Earth is to the Sun, and probably are too hot to have familiar oceans.

Water vapor has been found in the atmospheres of some of these: including HD189733b (2007)HAT-P-11b (2014)

12 “habitable zone”extrasolar planets now known(July, 2015) àliquid water likely to be stable at or near the surface.

Extrasolar Oceans?

Image R. Hurt, NASA Ames/JPL-CalTech. Public Domain.

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What Planetary Bodies have Oceans?

• Definitely Earth!

NASA Image, Public Domain