Open Earth Systems: An Earth Science Course For Maryland Teacher Professional Development

1. Open Earth Systems: An Earth Science Course For Maryland Teacher Professional Development EARTH HISTORY AND THE FOSSIL RECORD DAY 1 - Weds. July 9 AM Instruction: Solar System Origin, Early Earth & Habitability AM Activity: Dating the Earth – Simulating Radioactive Decay PM Instruction: Major Events in Earth History PM Activity: Exploring Geologic Time with TS-Creator DAY 2 - Thurs. July 10 AM Instruction: Climates of the Past AM Activity: Weathering, Erosion and Soils PM Instruction: The Fossil Record of Life PM Activity: Fossil Identification LINDA HINNOV, Instructor

2. OUTLINE • Origin of Solar System • The Planets • Meteorites • Early Earth • Habitability

3. Origin of Solar System Our Solar System formed about 5 billion years ago, from an enormous cloud of dust and gas, a nebula. The Sun, like other stars, was formed in a nebula, an interstellar cloud of dust and gas (mostly hydrogen). These stellar nurseries are abundant in the arms of spiral galaxies (like our galaxy, the Milky Way). Dense parts of clouds in these nurseries undergo gravitational collapse and compress to form a rotating gas globule. According to a new model outlined in a study in the July 1, 2010 issue of Astrophysical Journal Letters, a shock wave from an exploding massive star (supernova) several light-years away probably triggered the collapse of the molecular cloud that would become our sun and planets.

4. Origin of Solar System The globule is cooled by emitting radio waves and infrared radiation. It is compressed by gravitational forces and shock waves of pressure from supernovae or hot gas released from nearby bright stars. These forces cause the roughly spherical globule tocollapseand rotate. The process of collapse takes from between 10,000 to 1,000,000 years.

5. Origin of Solar System Central core and protoplanetary disk: As the collapse proceeds, the temperature and pressure within the globule increases, as the atoms are in closer proximity. The globule rotates faster and faster. This spinning action causes an increase in centrifugal forces (a radial force on spinning objects) that causes the globule to have a central core and a surrounding flattened disk of dust (called a protoplanetary disk or accretion disk). The central core becomes the star; the protoplanetary disk may eventually coalesce into orbiting planets, asteroids, etc.

6. Origin of Solar System Protostar: The contracting cloud heats up due to friction and forms a glowing protostar; this stage lasts for roughly 50 million years. If there is enough material in the protostar, the gravitational collapse and the heating continue. A Newborn Star and a Solar System: When a temperature of about 27,000,000°F is reached, nuclear fusion begins at the core of the Sun. This is the nuclear reaction in which hydrogen atoms are converted to helium atoms plus energy. This energy (radiation) production prevents further contraction of the Sun.

7. Origin of Solar System Young stars often emit jets of intense radiation that heat the surrounding matter to the point at which it glows brightly. These narrowly-focused jets can be trillions of miles long and can travel at 500,000 miles per hour. These jets may be focused by the star's magnetic field. Later, the Sun stabilizes and becomes a yellow dwarf, a main sequence star which will remain in this state for about 10 billion years. After that, the hydrogen fuel is depleted and the Sun begins to die.

8. Origin of Solar System Our Solar System is located in the outer reaches of the Milky Way Galaxy, which is a spiral galaxy. The Milky Way Galaxy contains roughly 200 billion stars. Most of these stars are not visible from Earth. Almost everything that we can see in the sky belongs to the Milky Way Galaxy. The Sun is about 26,000 light-years from the center of the Milky Way Galaxy, which is about 80,000 to 120,000 light-years across (and less than 7,000 light-years thick). We are located on on one of its spiral arms, out towards the edge. It takes the sun (and our solar system) roughly 200-250 million years to orbit once around the Milky Way. In this orbit, we (and the rest of the Solar System) are traveling at a velocity of about 155 miles/sec (250 km/sec). To reach the center of the Milky Way Galaxy starting from the Earth, aim toward the constellation Sagittarius. If you were in a spacecraft, during the trip you would pass the stars in Sagittarius one by one (and many other stars). From the Earth, our Milky Way Galaxy is visible as a milky band that stretches across the night sky.

9. Origin of Solar System Since we're inside the Milky Way Galaxy and we've never sent a spacecraft outside our galaxy, we have no photographs of the Milky Way Galaxy. Radio telescope data does, however, let us know a lot about it. The arms of the Milky Way are named for the constellations that are seen in different directions. The major arms of the Milky Way Galaxy are the Perseus Arm, Sagittarius Arm, Centaurus Arm, and Cygnus Arm; our Solar System is in a minor arm called the Orion Spur. The central hub (or central bulge) contains old stars and at least one black hole; younger stars are in the arms, along with dust and gas that form new stars. The great rift is a series of dark, obscuring dust clouds in the Milky Way. These clouds stretch from the constellation Sagittarius to the constellation Cygnus. The Milky Way Galaxy is just one galaxy in a group of galaxies called the Local Group. Within the Local Group, the Milky Way Galaxy is moving about 300 km/sec towards the constellation Virgo. Harlow Shapley (Nov. 2, 1885-Oct. 20, 1972), an American astronomer, was the first person to estimate the size of the Milky Way Galaxy, and our position in the galaxy (in 1918).

10. Origin of Solar System SUMMARY

11. CLICKER Question QUESTION: Our Sun began emitting light: a) when gravitational collapse occurred b) nuclear fusion reactions began c) with rotation of the nebula d) with a supernova explosion e) when Moon collided with Earth

12. The Planets

13. The Planets

14. The Planets

15. CLICKER Question QUESTION: Which other planet has a near-Earth day? a) Jupiter b) Venus c) Mars d) Mercury e) Pluto

16. Meteorites Geologic inventory of major impacts IMPACT SITES Barringer Meteor Crater, AZ. 35°02'N, 111°01'W; diameter: 1.186 kilometers (.737 miles); age: 49,000 years. asteroid – A big rock or aggregation of rocks orbiting the Sun meteoroid – A small rock orbiting the Sun meteor – The visible light that occurs when a meteoroid passes through the Earth’s atmosphere meteorite – A rock existing on Earth that was once a meteoroid Chicxulub, Yucatan, Mexico N 21° 20’, W 89° 30' 170 km diameter 64.98 ± 0.05 million years http://www.britannica.com/eb/art-89387 http://www.amnh.org/rose/meteorite.html http://solarsystem.nasa.gov/multimedia/gallery/Chicxulub-browse.jpg

17. Meteorites Types of meteorites 5% 1% 94% Iron meteorites are dominantly composed of iron metal, generally with between 5 - 20 wt. % nickel. They are sub-divided into many different groups on the basis of trace element chemistry. They can also be sub- divided according to metallographic texture. Stony-ironmeteorites have equal proportions of silicate minerals and iron-nickel metal. They are sub-divided into two major groups, mesosiderites and pallasites, which have very different origins and histories Stony meteoritesare made from the same elements as terrestrial rocks: Si, O, Fe, Mg, Ca and Al. Like terrestrial rocks, stone meteorites are assemblages of minerals: pyroxene, olivine and plagioclase, but unlike terrestrial rocks, they also contain metal and sulphides. http://www.nhm.ac.uk/jdsml/research-curation/projects/metcat/bgmettypes.dsml http://piclib.nhm.ac.uk/meteorite-blog/image.php?src=http://www.nhm.ac.uk/nature-online/space/meteorites-dust/images/types-l.jpg&from=/meteorite-blog/

18. Meteorites Types of meteorites Stony Meteorites (94% of all falls) 75 to 90% silicates + 10 to 25% Ni, Fe alloy CHONDRITES (97%) ACHONDRITES (3%) Chondrites are the most abundant, have VERY PRIMITIVE CHEMISTRY with Ca and Al rich inclusions known as "CHONDRULES" (mm-sized "beads") thought to have condensed from gases in the solar nebula, and flecks of Ni and Fe metals. Achondrites underwent melting, and closely resemble EARTH ROCKS, collected mostly when seen to fall. They have little to NO METAL and NO CHONDRULES. 1. Carbonaceous -- 1% carbon in matrix and organic compounds, including hydrocarbon chains and rings, and amino acids (outer asteroid belt) 2. Ordinary --the most numerous, comprising ~85% of all finds, with olivine, orthopyroxene mineralogy (middle asteroid belt) Microscopic view of a spherical chondrule, 1 millimeter in diameter. The bright, colored regions within its margins are mineral crystals. The black region between the crystals is glass and represents once-molten material. This chondrule is in Semarkona, an ordinary chondrite which fell in the Madhya Pradesh region of India. 3. Enstatite -- contain the mineral enstatite, a magnesium silicate (inner asteroid belt) http://meteorites.lpl.arizona.edu/chondrule.html http://www.meteorite.fr/en/classification/ordinarychon.htm

19. Meteorites Types of meteorites Iron Meteorites (5% of all falls) These irons are alloys of nearly pure nickel and iron, and thus are very heavy compared to normal rocks. When cut and polished, the crystals are seen to form a distinctive criss-cross pattern of elongate crystals, known as a Widmanstätten pattern, which indicates slow cooling. Presumably, therefore, irons represent the fragments of the core of an asteroid or large ‘planetoid.’ Gibeon (IVA) iron meteorite, Gibeon, Namibia. meteorites.wustl.edu/id/metal.htm http://tesla.jcu.edu.au/Schools/Earth/EA1004/Hazards/meteorites.html

20. Meteorites Types of meteorites Stony-Iron Meteorites (1% of all falls) 50% silicates + 50% Ni, Fe alloy Pallasites - named for the German naturalist Peter Simon Pallas; mixtures of metal and silicate material, in a complex network of green, yellow, or brown crystalline pods of olivine surrounded by a bright silver-colored iron-metal matrix. The Brenham (Kansas) pallasite consists of olivine pods in a silver-colored iron-metal matrix. http://www.meteorite.fr/en/classification/stonyiron.htm http://meteorites.lpl.arizona.edu/composition.html

21. Meteorites Origins of meteorites Isotopic and chemical signatures indicate that most meteorites came from about 100 original asteroids. The solar system condensed into dust particles and mm-sized balls called chondrules. Chondrules and dust were drawn together by gravity and formed the planets and the asteroids. Asteroids smashed by collisions formed chondrite meteoroids. These make up about 87% of all meteorites found. Some asteroids were so large that radioactive elements (mainly Aluminium 26) heated and melted their cores. The heavier metals (iron and nickel) sank inward and the lighter stony material floated outward, differentiating the asteroid. When these asteroids were smashed by collisions, they formed three types of meteoroids. The cores formed iron meteoroids (4%), the core mantle boundary formed stony irons (1%) and the mantle and crust formed achondrite meteoroids (8%). astronomy.neatherd.org/meteorites/families.htm

22. Meteorites Origins of meteorites ASTEROIDAL 99.99% percent of all meteorites are of asteroidal origin. CHONDRITES: Enstatite -- (inner asteroid belt) Ordinary -- (middle asteroid belt) Carbonaceous -- (outer asteroid belt) IRON: Originate from M-type asteroids, and are thought to be core fragments of large asteroids shattered by impacts.

23. Meteorites Origins of meteorites LUNAR MARTIAN Chemical compositions, isotope ratios, minerals, and textures of the lunar meteorites are all similar to those of samples collected on the Moon during the Apollo missions. Taken together, these various characteristics are different from those of any other type of meteorite or terrestrial rock. For example, all of the meteorites that are classified as feldspathicbreccias are rich in anorthite (plagioclase feldspar), mineralogically, and calcium aluminum silicate, chemically. That is, these meteorites have high concentrations of aluminum and calcium. Uniquely, the lunar highlands are composed predominantly of anorthite. Anorthite is much less common on asteroids and, to the best of our knowledge, on the surface of any other planet or planetary satellite. Of the 24,000 or so meteorites that have been discovered on Earth, 34 have been identified as originating from the planet Mars. These rare meteorites created a stir when NASA announced in August 1996 that evidence of microfossils may be present in one of these Mars meteorites. The 34 Mars meteorites are divided into three rare groups of achondritic (stony) meteorites: shergottites (25), nakhlites (7), and chassignites (2). Consequently, Mars meteorites as a whole are sometimes referred to as the SNC group. They have isotope ratios that are said to be consistent with each other and inconsistent with the Earth.

24. CLICKER Question QUESTION: Lunar and Martian meteorites are: a) nickel b) pallasites c) iron d) chondritic e) stony

25. Early Earth Chaotian Eon Chaotian is Solar System wide Proposed time scale by NASA scientists (Goldblatt et al., 2010) The Neochaotian began with the first light from the Sun. Its periods are the Hyperitian (the Titan Sun god Hyperion) for the time when gravitational collapse made the Sun’s first light brighter than its subsequent main sequence, followed by the Titanomachean (the war of Titans), to encompass the collision of proto-planets to form our present set of planets. The Eochaotianbegan when the Solar Nebula became a closed system with respect to the rest of the giant molecular cloud and encompasses the agglomeration of the Solar System constituents from the nebula. It includes the Nephelean Period, for the cloud that is the nebula, and the ErebreanPeriod (Erebus, darkness) for the proto-Sun, yet to be luminous.

26. Early Earth Late Chaotian Earth Proto-Earth “Tellus” original (“primordial”)atmosphere would have mostly been hydrogen and helium, like the gas giants. This atmosphere was lost due to a number of factors: • Its lower gravitational field (compared to gas giants) allowed escape of H and He • Solar wind stripped much of the atmosphere, until the magnetic field was established • Energy from planetesimalimpacts would send some of the gas into space http://www.scientificamerican.com/slideshow.cfm?id=the-night-sky-will-fade-to-black

27. Early Earth Hadean Earth The Hadean Eon begins after Theia (Proto-Moon) and Tellus (Proto-Earth) collided to form the Earth-Moon system. The Hadean is restricted to Earth’s geology, in contrast to the solar system wide Chaotian. Promethean, for the Late Heavy Bombardment, which would have vaporized the ocean and exterminated any pre-existing life; accordingly, we name the upper Neohadeanperiod For the lower Neohadean period (4.1 to 4.0 Ga), we suggest Acastan, after the 4.03 GaAcasta Gneiss. Procrustean(4.2 to 4.1 Ga) from Procrustes, whose bed fitted all life. Canadian, from crustal material dated back to 4.28 Ga is found in the Canadian Shield. Jacobianafter Australia’s Jack Hills, which yield the earliest zircons. .Hephaestean for the lower Palaeohadean (Hephaestus, the Olympian god of fire and blacksmith for the gods), for an extreme silicate-water vapor greenhouse and a molten crust, which solidified in ~10My Goldblatt et al. (2010)

28. Habitability

29. Habitability

30. Habitability The red region is too warm, the blue region too cool, and the green region is just right for liquid water. Because it can be described in this way, sometimes it is referred to as the "Goldilocks Zone.” Our Solar System Habitable Zone has been recently redefined from 0.95 astronomical units (AU, or the distance between Earth and the sun) to 1.67 AU, to a new range of 0.99 AU to 1.7 AU. Thus Earth is at the EDGE OF THE HABITABLE ZONE!

31. Habitability “Faint Young Sun Paradox” The problem:

32. CLICKER Question QUESTION: The “Faint Young Sun Paradox” assumes that: a) Earth was molten for billions of years in the past b) Earth was frozen for billions of years in the past c) Earth has always been at the same distance from Sun d) Sun was less luminous in the past e) Sun will become faint over the next billion years