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PSSC: The Earth Sciences

Dr. Neil Suits, Assistant Professor of Earth ScienceOffice: Sci 118 Phone: 896 ‐ 5931

neil.suits@msubillings.edu

Best times to see me are right after class on Mondays and Fridays

Email also is good.

PSSC: The Earth Sciencesreadings and quizzes

8th EditionCh 14: pp 358-368Ch 15: scan the chapter, look at the figures and read the captions, know all the planets in the solar system, know the two types of planets, know terms in boldface.Ch16: 406-409; 411-412; 418-425Ch 17: 432-435; 439-447(mineral formation)

7th EditionChapter 14, pages 388-398Chapter 15, scan the chapter. Know the planets of the Solar System, know the two types of planets, know terms in boldfaceChapter 16, pages 438-441; (Places & Time) 443-446; Moon, etc. 452-460Chapter 17, pages 466-470; Read Figure Captions; 473-482.

First quiz, next Wednesday.

PSSC: The Earth Sciencestopics we will cover

Time and Place: Where the Earth and Solar System come from.

Basic Geology: How rocks and minerals are formed as well as mountains and oceans. We will also look at the geology of Montana, and take a quick tour through the fossil record.

Weather and Climate: What is the difference between weather and climate? What controls the weather and what are the facts about Climate Change?

~14 GA

(Giga Annum: Billion Years)

today

~ 300,000 years after the Big Bang

The first map of the Universe. Not homogeneous.

Cosmic microwave background (CMB) anisotropy. First detected by the COBE DMR instrument.

Typical spiral galaxy. Similar to ‘our’ Milk Way Galaxy’

~100,000 light years in diameter

We would be about here

~ 100 Billion Stars~100,000 light years across

We are not alone.

About 80 billion galaxies in the observable universe.

About 400 billion stars in the Milky Way galaxy (but that may be a bit larger than average)

Many (most?) of those probably have planets.

How many of those planets are terrestrial (Earth-like?)

How many have life?

Stars

• Sun

– An average star

– Reference for understanding other stars

• Massive, dense balls of incandescent gas

• Powered by nuclear fusion reactions in their core

(E = mc2)

Origin of stars

• Gaseous nebula– Mostly hydrogen

• Shock waves induce gravitational collapse– Gravitational energy

released into higher temperatures and pressures

• Protostar– Accumulation of gases that

will become a star

http://faculty.rmwc.edu/tmichalik/NebandStar.htm

Star Birth and Formation: Protostars

The internal structure of the Sun

Stellar modeling

• Core– Very hot, most dense region

– Nuclear fusion releases gamma and x-ray radiation

• Radiation zone– Radiation diffuses outward

over millions of years

• Convection zone– Structured by hot material

rising from the interior, cooling, and sinking

– Upper reaches: visible “surface” of star

– Sun surface temp. ~5,800 K

Lifetime of the Sunor any star

• Our Sun converts about 1.4x1017 kg of matter to energy each year – About 2,700 6000 lb SUVs!

– E = mc2 ( units = kg m2/sec2 = Joules)

• Lifetime of a star depends on its mass– Less massive stars have longer lifetimes

– More massive stars have shorter lifetimes

• Born 5 billion years ago

• Enough hydrogen for another 5 billion years

But not every star is like the Sun……

The Crab Nebula in Lyra

Remnants of a supernova

….the most violent event ever seen in the universe — flashed into view on the morning of March 19th.

"This burst was a whopper," said Swift principal investigator Neil Gehrels of NASA's Goddard Space Flight Center in Greenbelt, Md. "It blows away every gamma ray burst we've seen so far."

….the March 19th, 2009 burst had a redshift of 0.94, corresponding to a look-back time of 7.5 billion years — several thousand times more than the nearby galaxies.

The farthest object ever seen by the naked eye.

Most gamma ray bursts occur when massive stars run out of nuclear fuel. Their cores collapse to form black holes or neutron stars, releasing an intense burst of high-energy gamma rays and ejecting particle jets that rip through space at nearly the speed of light like turbocharged cosmic blowtorches. When the jets plow into surrounding interstellar clouds, they heat the gas, often generating bright afterglows. Gamma ray bursts are the most luminous explosions in the universe since the big bang.

Why are some stars bright and others are not?

• Differences in stellar brightness1. Amount of light produced by

star

2. Size of star

3. Distance to star

• Apparent magnitude– observed brightness (how bright it

looks from Earth)

• Luminosity– actual brightness (how much light

the star is actually putting out)

What does the color of a Star tell you?

• Color variations apparent: red, yellow, bluish white

• Color related to surface temperature

– Blackbody radiation curves

– Red: cooler stars

– Blue: hotter stars

– Yellow: in between (Sun)

• Classification scheme

– Based on temperature: hottest to coolest

– O, B, A, F, G, K, M

Star color ~ star temperature

Life of a star

• Protostar stage– Gravitational collapse

– Density, temperature and pressure increase

– 10 million K: fusion ignition temperature

– Dynamical equilibrium• Inward force of gravity

• Outward pressure of fusion energy

– Star enters main sequence

Hertzsprung-Russel

Diagram

A stars fate depends on its mass

Fate of the Sun…. First a Red Giant, then a White dwarf within a planetary nebula

The Crab Nebula in Lyra

Remnants of a supernova

Magnetic fields around a sunspot

‘Winds' and ‘Waves’ on the surface of Sol

SUN Rocky

(Terrestrial) inner planets

The giant Gas planets of the outer solar system

Hydrogen, Helium, methane, water, ammonia

Silicates with Iron cores

Hyd

rog

en (7

4%

), so

me h

elium

(24

%)

Planet summary

Mercury

Venus

Earth

Mars

The Martian ice cap

Frozen water?

Craters on Mars

Olympus Mons

The largest mountain in the Solar System

Why is it so big?

~ 625 km (324 miles) diameter

Scarp Height~ 6 km (4 miles)

Olympus Mons on an overcast day

Evidence for water on mars

Wind-formed dunes on MarsAtmosphere: 0.7% of the Earth’s atmospheric pressure; 95% Carbon Dioxide (CO2), 3% Nitrogen (N2); 1.7% Argon, 0.1% Oxygen (O2)

View of the surface of Mars from the Martian lander

Figure 15.09a

Jupiter

Figure 15.09b

Movie of Jupiter

Saturn

Titan: moon of Saturn

landing400.mov

Uranus

Neptune

Pluto

Smaller bodies of the Solar System

• Comets, asteroids, meteorites

• Leftover from solar and planetary formation

• Mass of smaller bodies may be 2/3 of total Solar System mass

• Bombard larger objects– Comet Shoemaker-Levy 9

fragments (bottom)…– … and strikes Jupiter (July

1994)

Comet structure

• Small, solid objects

• “Dirty snowball” model

– Frozen water, CO2, ammonia, and methane

– Dusty and rocky bits

• Comet head

– Solid nucleus and coma of gas

• Two types of tails

1. Ionized gases

2. Dust

• Tail points away from Sun

Meteors and meteorites

• Meteoroids – Remnants of comets and

asteroids

• Meteor– Meteoroid encountering

Earth’s atmosphere

– Meteor showers: Earth passing through comet’s tail

• Meteorite– Meteoroid surviving to strike

Earth’s surface

– Iron, stony (chondrites and achondrites) or stony-iron

Figure 15.19b

Figure 15.19a

Our moon: Luna

Current hypothesis: Luna was formed as a result of an impact by a Mars-sized object in the early stages

of Solar System formation.

Lunar impact craters

Crater Tycho

Close up of Tycho