Perspectives On The Universe
by
Dr. Philip Petersen
Solano Community College
The Overall Perspective
Units of Measurement
Distance:
meter (m) = 1/10 millionth distance from N. Pole to equator
nanometer (nm) = 1 billionth of a meter
micrometer (µm) = 1 millionth of a meter
millimeter (mm) = 1 thousandth of a meter
centimeter (cm) = 1 hundredth of a meter
kilometer (km) = 1,000 meters
1 meter = 39.37 in
1 AU = Astronomical Unit = distance from earth to sun.
1 LY = Light Year = distance light travels in a year
1 pc = parsec - 3.26 LY
megaparsec = 1 million parsecs
gigaparsec = 1 billion parsecs
Mass:
1 gram = mass of one cubic centimeter of pure water
1 kilogram = 1,000 grams
Time:
1 second = 1/86,400 of a mean solar day
1 hour = 3,600 seconds
Powers of 10:
10power = 1 with power number of zeros
10-power 1/(1 with power zeros)
Cosmic Zoom: Smallest to Largest
superstrings size = 10-35 m
hydrogen nucleus (proton) size = 10-15 m
typical atom size = 10-10 m
child (5 yr old) size = 1 m
earth size = 107 m
our solar system size = 1013 m
the milky way galaxy size = 1021 m
visible part of the universe size = 1026 m
A Brief History in Time
13.7 billion years ago -- The Big Bang
13.5 billion years ago - First Light - First stars ignite
13.5 - 1 billion years - Quasars - very active galactic cores
12 - 13.5 billion years - birth of the Milky Way galaxy
10 billion yrs- Now - Active Galaxies - moderately active cores, decreasing in number
4.6 billion years - birth of the Solar System and the Earth
3.5 billion years - large asteroidal impact - destroyed all life
3 billion years - earliest record of life - Australian bacterial fossils
67 million years - extinction of dinosaurs by asteroid colliding with earth
7 million years - hominid in Africa
120,000 years - our ancestors
12,000 years ago? - building of Sphinx
5,000 BC - Sumerian and Egyptian civilization begin
From Earth's Perspective
The Celestial Sphere (Pythagoras)
Celestial sphere--imaginary sphere on which the 'fixed stars' are located--gives angular position of objects in the sky, has arbitrary size, and earth turns underneath it.
Zenith--point directly overhead on sphere.
Celestial poles--points just above N. and S. pole.
Meridian--circle passing through poles and zenith.
A great circle--divides sphere in half.
A Great Circle (the meridian is an example) on the sphere has 360 degrees.
1 degree = 60 (arc)minutes = 60'
1 (arc)minute= 60 (arc)seconds = 60"
Celestial equator--great circle on the sphere formed by cutting through earth's equator.
The ecliptic--great circle which is sun's path--tilted 23 ½ from the celestial equator.
Angular separation (distance)--no. of deg., min., sec. between objects or points on sphere.
Angular size--angle an object subtends at observer's
distance.
Celestial Coordinates:
To find a city on the surface of the earth (a sphere)
we need two coordinates--longitude and lattitude.
The two 'celestial coordinates' on celestial sphere are analogous to longitude and lattitude.
Right ascension--0 to 24 hours (like time zones, but on the sky). Starts at star Psi Piscium, present position of the vernal equinox, point where the sun crosses the celestial equator.
Declination--0 to ±90. (Lattitude is N. and S.)
Precession of the Equinoxes--earth's axis traces out a circle on the sky every 25,800 years, and the point of the vernal equinox shifts through all the signs of the zodiac.
Zodiac--the circular band of 12 constellations the sun passes in front of, one cycle in a year. Called the 'circle of animals'--the 12 astrological signs.
Astrology--mother of Astronomy--attributes significance to planetary positions in the Zodiac.
Celestial Motion
Stellar motion: 88 constellations or 'states' in the sky; an identifiable star group is an asterism.
1. 24 hour cycle due to earth's rotating under
them. Makes stars move rapidly westward. 'Circumpolar' stars never set.
2. Eastward motion of about 1/day caused by
earth revolving about the sun.
Siderial day--23 hrs 56 minutes. Motion of sun relative to stars.
Solar motion:
Mean solar day--24 hours by definition. Return of sun to same angle of view relative to the horizon.
seasons caused by tile of earth's axis, solstices --maximum and minimum light, equinoxes equal light on northern and southern hemisphere.
Planetary motion:
retrograde motion--apparent backtracking of
planets in sky from earth's perspective.
inner planets--Me and Ve--stay within 'maximum elongation'.
conjunction vs opposition
Lunar motion:
tidally locked--gravity makes same side (with a bulge) face earth.
Synodic period--29.5 days--cycle of phases.
Length of day on the moon.
Siderial period--27.3 days--with respect to stars.
Lunar phases--see diagrams.
Brief History of Astronomy:
5,000 BC--Sumerians--astrology and '12th planet'?
2,500 (or 8,500) BC--sphinx and great pyramid.
1,600 BC--Babylonians--star and planet tables.
1,500 BC (or much earlier)--Hindus--cycles of cosmos and lifetime of sun.
500 BC--Pythagoras--earth and heavens spherical.
350 BC--Aristotle--physics of forces, geocentric universe.
250 BC--Aristarchus--first sun-centered system.
200 BC--Erastosthenes--accurate size of earth.
130 BC--Hipparchus--epicycle, precession, charts.
7 AD?--Wise men tracked the Christmas star--Saturn conjunct Jupiter?
125 AD--Claudius Ptolemy--accurate geocentric model.
400 AD Hypatia: fall of the Alexandrian Library
From The Sun's Perspective
Aristarchus--200 BC--first sun-centered model.
William of Occam--1200 AD--Occam's razor--simpler theories are better.
Nicolas Copernicus--De Revolutionibus--1543
Features of his heliocentric model:
1. Planets still on spheres, but centered on sun.
2. Stars still on a sphere, but more distant than
in Ptolemy's model.
3. Planets in proper order from sun.
4. Planetary distances calculated--close to modern values.
Giordano Bruno--burned at stake in 1590--stars are suns with planets, beings on them.
Tycho Brahe and Johannes Kepler
Tycho Brahe--1546-1601--Observed planets very accurately--found orbits--especially Mars--
were not circular as Copernicus still held.
Johannes Kepler (1571-1630)--Found the true shape and motions of planets about the sun from Brahe's data.
Kepler's 3 Laws of Planetary Motion:
1. Planets move in elliptical orbits with the sun as a focus.
2. A line from the planet to the sun sweeps out equal areas in equal times. Thus planets and comets move more slowly farther from the sun.
3. P2= a3. P = planetary period--time for 1 revolution. a = avg. distance from sun = semimajor axis (in AU)
Eccentricity: dist. between foci/widest dist.
Planetary Distance (in AU):
Copernicus vs Modern
Mercury 0.38 0.387
Venus 0.72 0.723
Earth 1.00 1.000
Mars 1.52 1.524
Jupiter 5.2 5.203
Saturn 9.2 9.539
Gravity and Laws of Motion
Galileo's Accomplishments:
1. The law of inertia--objects continue at rest
or a constant speed in 1D motion. (Demo)
Natural Motion--without force.
2. Things fall in gravity with a constant acceleration g = (9.8 m/s)/s.
3. Inclined planes slow the acceleration of gravity. (Demo)
4. He invented the pendulum clock. (Demo)
5. He gave us first relativity--motion of object depends on motion of an observer. (Demo)
6. First telescope observations: (Slides)
a. calculated height of mtns. on the moon.
b. observed periods of 4 satellites of Jupiter.
c. phases of Venus.
d. rings of Saturn.
e. sunspots.
Newton's Accomplishments:
1. Observed first spectrum with prism.
2. Developed calculus to explain gravity and
Kepler's planetary motion.
3. Developed his three 'laws' of motion. (Movie).
I. Objects continue at the same velocity,
unless acted on by an unbalanced force.
(Demo)
II. F = ma (Weight vs mass--demo)
III. For every force there is an equal and
opposite force acting back on the actor.
4. The Universal Law of Gravitation
F = G m1m2/d2.
Gravity is a weak force (balloon demo).
5. Tidal Force:
a. Tides on earth oceans.
b. can break apart satellites.
6. Orbits.
7. Center of Mass.
Albert Einstein (1880-1955)
Special Theory of Relativity-1905 (high speed
motion):
Postulates (hypotheses):
1. The laws of physics are the same for any inertial observer (moving at const. v wrt stars).
2. Speed of light, c, in a vacuum is the same for all inertial observers.
Extraordinary Consequences:
1. Objects contract in the direction of motion.
2. Time slows for a clock moving near c.
3. No object can move faster than c.
4. Mass increases as the speed of light is approached.
5. Mass may be converted into energy and vice versa by E = mc2. Fission, fusion, and antimatter conversion. (E = energy, m = mass, c = speed of light = 3 x 108 m/s.)
General Theory of Relativity
(a gravity theory):
Ingredients:
The Principle of Equivalence: acceleration ~ gravity
Riemann's Curved Geometry: acceleration ~ curved space-time
( ' ~ ' means 'is equivalent to'.)
This implies: gravity ~ curved space-time (Einstein's Field Eqns.)
This is important when objects are massive, like sun or black hole. Supercedes Newton's Law in these cases.
Three experimental-observational proofs of General Relativity:
1. Perehelion precession of Mercury's orbit. (Slow rotation of
ellipse.
2. Light bends near the sun.
3. Time slows in a strong gravity field. Gravitational redshift, and clocks flown in planes vs on ground.
Waves:
Characteristics:
wavelength, --distance of repetition (crest to crest).
frequency, f--no. of complete cycles passing a point in a given time (cycles/sec = Hertz or Hz).
wave velocity, v--the speed of a crest (m/s).
Wave formula: v = f . Note: if you know f you can get or vice versa (for light v = c is known).
Ex. Calculate the frequency of light with wavelength = 3 m.
f = c/ = 3 x 108 m/s/3m = 108 cycles/s (Hz).
The Electromagnetic Spectrum: light is an electromagnetic wave. All wavelengths are possible. (Overlay.)
Spectral Types:
1. Continuous (Black Body)--a hot, dense gas with a common temperature. (See Plank curve overlay.) Wien's Law relates surface temperature, T, to peak wavelength. T = constant/peak .
2. Bright line (emission)--a hot sparser gas, temperature
variations. Collisions excite electrons, and they give off
well-defined wavelengths.
3. Dark line (absorption)--a cool gas in front of a hot, dense gas s with a continuous spectrum.
Why are there spectral lines?
Note the spectrum of the sun in the overlay. How did the dark lines get there?
Atoms are made up of protons and neutrons in the nucleus and electrons 'in orbit' about them.
Example--The Hydrogen Atom:
Quantum Theory says electrons have orbits of certain energies--this is like different sized stair steps. They give off light when
they fall to a lower lever (emission) and absorb it when they encounter just the right energy light (absorption).
See diagram of H atom energy levels.
Elements are identified in the periodic table and have their individual 'thumbprints' of spectral lines.
The number of the element = the atomic number = #protons
= #electrons in a neutral atom.
Spectroscopy--study of spectra.
Spectroscope (spectrometer)--device to study light spectra.
Planck's Law--the energy of a photon, or light quantum (particle or bundle), is proportional to its frequency: E = hf.
The Doppler Effect:
Light lowers in frequency when source has relative velocity away from observer (red shift), raises in frequency when approaching (blue shift). Relative velocity can be obtained from the frequency shift.
Examples: Redshift indicates universe is expanding. We can also get velocities of rotation of planets, stars, galaxies.
r2 Law of Light:
Light intensity diminishes as the square of the distance from the source. If we know, for example, how much light reaches us from a star, we can calculate it's distance. This is also called the luminosity-distance relation.
Reflection and Refraction
Principle of reflection:
the angle of incidence equals the angle of reflection--for all mirrors.
A parabolic mirror creates an image with no distortion.
Spherical mirrors (cheaper to make) work only close to the axis.
Principle of refraction:
light bends when it passes at an angle between two media with
different speeds of light like air and glass--lenses utilize this
principle to focalize images.
Lenses
The Focal length of a lens is the distance parallel rays entering the lens focus to a point.
Rays from a distant object may be considered to be parallel rays.
A convex or converging lens is curved outward on both sides.
A concave or diverging lens is curved inward on both sides.
Eyeglasses are often convex-concave.
Telescopes
Reflecting or Newtonian telescope (reflector): A large curved objective mirror focuses an image, a small eyepiece lens magnifies it. The image is inverted.
Refracting telescope (refractor): A large objective lens (usually converging) focuses an image and a small eyepiece lens magnifies it. The image is also inverted.
Seeing--the following conditions interfere with clear viewing:
1. Atmospheric turbulence--why stars twinkle.
2. Atmospheric absorption--some wavelengths.
3. Weather--cloud cover.
4. Light pollution--city lights.
Powers of Telescopes:
1. Light gathering power--proportional to the area of objective.
2. Magnification--m = F/f (F focal length of objective, f focal length of eyepiece)
3. Resolution--the angle of separation at which two objects merge and look like one.
Interferometry: using two radio telescopes or more and time delays to simulate on large telescope. Usually a radio telescope.
Satellites: necessary for most infrared, x-ray, gamma ray, micro-wave, UV. Uhuru--xray satellite discovered first black hole.
The Earth-Moon System
The parallax of a feature on the moon over a night gave Ptolemy the distance to the moon in earth diameters (diagram on board).
The following formula was then used to find to find the diameter of the moon. It can be used to find the diameter of any object.
Diameter = Distance x Angular Diameter
(in radians, 1 radian = 57.3o)
The moon's orbit is not perfectly circular (overlay).
Tidal force of the moon made the earth an oblate spheroid.
Spring tides have a higher high tide caused by the alignment of earth, moon, and sun.
Neap tides have a lower high tide, as the sun is at right angles to the moon's position.
Eclipses:
For either lunar or solar, the moon's orbit (tilted by 6o) must cross ecliptic plane at one of two positions called lunar nodes.
In addition, for a lunar eclipse, the sun and moon are in opposition (full moon). For a solar eclipse, the moon is between the earth and sun (new moon).
A lunar eclipse is the same everywhere on earth. A solar eclipse is total only on a 50 mile-wide swath across the earth. Thus lunar eclipses are more frequent in a given location than solar. (See overlay).
A lunar eclipse always involves the whole moon but may be gray instead of totally dark. This is a penumbral eclipse.
A solar eclipse is annular when moon is closer to earth.
Total solar eclipse returns every 18.6 yrs (Saros cycle).
The Moon:
Age--4.6 billion years (same as earth).
Origin--early collision of an asteroid with earth, vaporizing material which condensed into the moon.
Atmosphere--none.
Tidal locking--same side always faces earth. The moon's denser core was pulled closer to the earth, and tidal force held it there.
History--cratering 4.2-3.9 billion years, volcanism 3.8-3.1 billion years ago. How do we know? Dating of moon rocks (overlay).
Features:
Highlands--higher areas than crater floors covered with lava--called maria (singular--mare).
Regolith--powdery soil pulverized by micrometeors.
Rays--splayed out lines of material from large craters.
Rills--solidified lava rivers in fissures.
Exploration: (see overlay and film?)
Earth:
Age--4.6 billion years by radioactive isotope dating.
Atmosphere--80% Nitrogen, 20% Oxygen, trace of Carbon Dioxide. Pressure = 14.7 lbs/sq in. Originally lots of CO2, but oceans absorbed it, plankton and plant life converted it to O2.
Troposphere--0-10 km--weather here. Planes must go above.
Stratosphere--11-50 km--ozone layer (helped life move to land)
Mesosphere--50-90 km --temperature decrease
Ionosphere--above 90 km--aurora generated here--temp. rises
History--earth was once molten, radioactivity provided heat to keep the core molten, substances segregated. We know core is denser iron and nickel because density of earth = 5.5 g/cm3, but surface rocks have a lower density than that.
Layers of the earth: (see overlay) In addition part of the mantle and the whole crust make up the lithosphere, the rolling crustal plates. Wegener's theory of continental drift. (See map.)
Magnetosphere: the realm of the earth's magnetic field extending into space. Electrons in the solar wind are trapped in the Van Allen Belts (overlay). Aurora (northern and southern lights) caused by electrons in solar wind whirling around magnetic field lines and radiating.
Weather: earth's rotation yields coriolis force--winds counter- clockwise in northern hemisphere, clockwise in southern.
The Solar System:
Origin: the nebular theory fits most of the facts.
The nebular theory:
1. The Big Bang produced lumpy clouds--COBE satellite.
2. Recycled star stuff with heavier elements combined with H and He gas from Big Bang, and gravity pulled it together. There were two supernova in our region.
3. The gas cloud collapsed to a spinning disk and a globe in the center.
4. It heated as it collapsed, the center hotter than outer regions: Helmholtz contraction.
5. The sun's magnetic field slowed its rotation by dragging on
electrons.
6. There were swirls formed to predate satellite systems.
7. The inner regions were too hot to allow light gases to collect.
This left heavier elements and produced terrestrial planets.
8. The outer regions were cool enough to allow large amounts of H and He to collect into the Jovian Planets.
9. Dust collected into planetesimals, planetesimals into protoplanets. Gravity smoothed the larger objects to spheres.
10. All planets, the sun, and satellites rotated and revolved in the same direction (prograde). Some planets (Venus, Uranus and Pluto) rotate retrograde because of large collisions (Velikowsky).
Scale: Diameter of Sun = 10 x Diameter of Jupiter
Diameter of Jupiter = 10 x Diameter of Earth.
Bode's Law: Planet Dist. in AU = (3x2n-1 + 4)/10, n = 1, 2, 3, Planet Prediction Actual Distance
Mercury 0.4 0.39
Venus 0.7 0.72
Earth 1.0 1.00
Mars 1.6 1.52
Ceres 2.8 2.8 (Largest in asteroid belt)
Jupiter 5.2 5.20
Saturn 10.0 9.54
Uranus 19.6 19.18
Neptune 38.8 30.06
Pluto 77.2 39.44 (was Pluto an original?)
No reasonable explanation why this works.
Distances found by radar ranging--bouncing radio waves and timing.
Mass:
Found using Newton's version of Kepler's 3rd Law a3/P2 = kM.
This gives mass of sun. Then, let M = the mass of a planet with a moon in orbit about it. Planets without moons have masses determined by orbiting spacecraft or deviations in trajectories (paths) of passing objects.
Planetology:
Example--content of Atmospheres: depends on
1. Volcanism, and origin of planet.
2. Surface temperature--a measure of average speed of atoms and molecules.
3. Surface gravity and escape velocity.
MERCURY
Mariner 10 in 1973 mapped 60% of Surface.
D = 1.4 D(moon) = .35 D(earth)
No axial tilt
Day = 176 earth days = twice orbital period
1. Same density as earth implying large metallic core, solid because it is a small planet. Rocky mantle cut down by a large impact or early solar bombardment.
2. Extremely thin atmosphere of helium, sodium, and potassium continually escaping into space. Temps: 425K to 100K (-170C).
3. Rotates 3 times for every 2 revolutions--same side faces sun at alternate perehelia (semiperiodic tidal locking).
4. Features: craters and basins filled with lava (like moon) and scarps formed as planet cooled. Core was once liquid.
5. A stronger magnetic field than expected, considering slow rotation and cool core. A distorted magnetosphere.
6. Same sequence and timing of formation of moon and mercury. No plate techtonics.
7. Large impact crater--Caloris Basin (like Orientale Basin on moon)--jumbled hills on opposite side of planet.
Venus
0.95 DEarth
Surface Temp. = 900 OF, Greenhouse effect.
Atm. Pressure = 90 x Earth's
1. Atmosphere: 96% CO2, 3.5% Nitrogen. Clouds of sulfuric acid, sulfur dioxide, sulfur, indicating live volcanism?
2. Rotation: siderial--243 days, solar-117 days.
3. Surface Features: 27% Lowlands, 65% rolling plains, 8% highlands. Cones, faults, craters, multiple lava flows.
A. Ishtar Terra--US sized lava-filled basin--highlands
B. Maxwell Montez--Everest's height--100 km Diam.
Cleopatra, crater on it's flank.
C. White magnetite (?) above 2.5 km.
D. Surface--young to 800 million years--crater cycle.
E. Surface too cracked to form plates, but molten core
distorts surface with mantle convective flow.
F. Atmosphere rotates much faster than surface creating wind features--impact ejected to west, streaks near
ridges.
G. 100,000 small 'shield' volcanos--clusters due to hot spots, volcanic material near surface. No plumes show
because of high pressure.
H. Lava Channels--one 7,000 (!) Km long
I. Calderas over 100 km in diameter.
4. Visiting Spacecraft: 1962-1975-Three Mariners (USA) rudimentary mapping.
1962--Venera--Soviet surface landing.
1989-90--Magellan (USA)--accurate radar maps.
MARS
0.53 Dearth, -140 oC to 20 oC
Atmosphere 95% CO2, 3% N2, 2% Ar
24 hr day, 25o axial tilt like Earth
1. Small liquid core and magnetic field. Much thicker solid
mantle than Earth. Thin basaltic crust (20 km).
2. Surface Features: Largest in solar system
A. Two hemispheres separated by 1 km high scarp tilted 35o from equator:
i. To the North--sparsely cratered lowlands.
ii. To the South--very cratered highlands.
B. Tharsis province--just North of scarp--a giant volcanic bulge 5,000 mi long, 4 mi high.
i. 3 giant volcanos near crest--195-250 mi across,
15 mi high.
ii. Olympus Mons--NW flank 400 mi wide, 16 mi hi.
iii. Clouds of ice near peaks of mtns.
C. Fractures radiating out from Tharsis:
i. Valles Marineris--to east---3,100 mi long. Water
erosion. Flooding onto lowlands-Chryse Planitia.
ii. Coprates Chasma--430 mi wide, 4 mi deep landslides.
iii. Other canyons--blocks collapsed--chaotic terrain.
3. Dust storms--closer to sun by 20%, 45% hotter--dark spots.
4. Phobos--closest satellite--will take plunge in 100 mill. Yrs.
Stickney--big crater on Phobos. Deimos--smaller satellite.
5. Visits: Mariners 4, 6, 7, 9 orbit, Viking 1, 2 landers.
Pathfinder landed lakebed like Mono Lake, satellite photos.
6. Life? Viking--Amino Acid-like. Antarctic meteorite-bacteria?
Jupiter:
11.2 Dearth
-150 C Outer ammonia crystal cloud
80% H, 19% He, traces of water, methane, ammonia
Large magnetic field--over 10x Earth's
Differential rotation 9.8 hrs at equator
Features:
Great Red Spot--cyclonic storm, lasting over 300 yrs.
Belts (darder outward flow), and zones (lighter inward flow).
Liquid and solid metallic hydrogen in core--p's & e-s--current
6% oblate sphere.
A ring of dust particles.
Large Van Allen Belts.
Emits more energy than it receives (true of all Jovian Planets).
Visiting Spacecraft:
1973-4 Pioneer 10, 11 flyby, 1979 Voyager I & II moons
1997--Galileo plunged into atmosphere--found less water
than expected.
Satellites: 60
4 Galilean moons about size of Mercury.
Io--9 volcanic plumes, unique surface volcanism, terraced hills at poles.
Europa--streaks and fissures in ice crust a few km wide.
Life underneath ice?--liquid subsurface ocean?
Ganymede--largest, had plate techtonics in past multiple
parallel ridges like ruffled potato chip, cratering. Large
dark region of original surface.
Callisto--vast crater-Valhalla--with ruffled rings, ice & rock.
Saturn
9.5 Dearth
Same atmosphere as Jupiter, but cloud obscures belts and zones.
Tilt 26.7 degrees, Day = 10.5 hours, very oblate
1/20th magnetic field of Jupiter
Features: belts and zones like Jupiter, small rocky core, occasional storms. Explored by Voyager I, II in 1979.
Rings: 8 Rings--100,000 miles in diameter.
Gaps are less visible rings, in particular Cassini Division.
F Ring braided and shaped by shepherd moons.
20-100 m thick, kept from assembling by tidal force.
Composed of ice and dust particles a micron to 10 m in size.
They disappear for a few weeks every 15 years.
Source may be unassembled nebula particles, broken up moons, or magnetic segregation.
Spokes--black radial clouds caused by interaction with planetary magnetic field.
Moons: 18. Titan--larger than Mercury, thick atmosphere (98 % N, 2% Methane, 1.6 Pearth). Liquid methane or Nitrogen oceans, similar to early conditions on earth except very cold. Hydrogen cyanide, ethane, and other organic compounds possible on surface. Bright, icy continents.
Other moons are shiny, icy on the surface with some flow from interior, very cratered.
Uranus
4.0 Dearth, -384 F--surface temp.
Same atmosphere as Saturn, more methane, no visible belts.
Axial tilt over 90o, Magnetic axis 59o off, Mag. field like Sat.
Extreme differential rotation--16 hrs at equator, 28 hrs at poles.
(Uranus cont.)
Features: Again dominated by mol. H and He, small rocky core, more methane giving surface blue-green appearance.
Some underlying zonal flow and a deeper layer of water.
Strong UV emission--electroglow. Twisted magnetotail.
Rings: 11. faint ring system discovered by time lapse photos--shepherd moons hold black (.05 albedo) rings in place.
Moons: At least 15. Strong radiation from planet turns methane in icy moon surfaces dark, so that icy moons are gray in appearance. Named after characters in Shakespeare (Oberon, Titania, Ariel, etc.). Moons are not in ecliptic plane like most satellite systems--in same plane as Uranus' equator!! Ur. discovered by Herschel. Miranda--Probably broken up by collision and reformed--radical mountains and valleys, fissures. Smallest and closest. Other moons have old cratered surfaces, faults, scarps, and occasional new ice flow portions.
Neptune
3.9 Dearth, 60 K, gives off 3x energy received
Axial tilt 29o, Magnetic axis off by 47o, extreme differential rot.
Features: Molecular H and He, methane makes blue, Hydrogen sulfide upper cloud layer with shape-changing cirrus white methane clouds. Great Dark Spot 3 earths large.
Rings: 4 dark rings with shepherd moons.
Moons: At least 8 gray moons, most within equatorial plane. Exception is Triton: 2700 km diam. 23o orbital incl. to equator. Has tenuous N and methane atmos., pink and blue. S. polar cap looks like cantaloupe. Young surface, gaseous methane or N geysers, glaciers. Nereid: eccentric captured asteroid--340 km diam.1.4-9.6 mill. km.
Discovered by Galileo, but not recognized, explored by Voy. II
Pluto
Moon-Charon-double tidal locking
Dark spot, cold
Planet X: a planet(?) disturbing Neptune--Naval Observatory 5 x mass of earth, 5 x distance to Pluto.
Nemesis: a failed star (< .08 sun--Alvarez) with a 26 million
year orbital period relating to periodic species extinction--it would knock asteroids toward the earth as comes to sun.
Solar System Debris
Comets: Nucleus is a dirty snowball (Whipple) from 1-10 km.
We see ion tail, a veil of evaporated ions swept back by solar
wind. It always points away from the sun, and has a magnetic
field creating a glow like the aurora borealis. A dust tail, visible
mainly in the infrared, is left in its wake. Comets break up a bit each time they come close to the sun. Debris in earth's orbit creates a meteor shower at a regular time each year. (Like the Leonids--from constellation Leo in mid-November.)
The radiation, solar wind sublimate jets, making nucleus spin.
Most comets spend most of their time in the Oort Cloud far beyond Pluto. (Few in the Kuiper Belt just beyond Pluto.)
Asteroids: space rocks. The asteroid belt: over 100,000 between Mars and Jupiter. Ceres--largest 1000 km diam., Pallas, Vesta, Juno. Either it is a broken up planet or Jupiter's gravity kept it in pieces. Kirkwood gaps--fraction of PJupiter.
The Trojans: 700 carried around in gravity wells in front of
and behind Jupiter in its orbit (at Lagrangian Points).
The Amors--5 large ones that come near earth's orbit.
The Apollos--5 large ones that cross earth's orbit.
Many others in Kuiper Belt, Oort cloud, and dispersed.
Meteors--shooting stars, rocks burning up as they fall in atmos.
Meteoroid--rock in space, Meteorite--rock on earth from space, stony to stony-irons. Carbonaceous chondrites-stars. 11 m/s
The Sun
How big? DJupiter 10 x DEarth
DSun 10 x DJupiter
More precisely, DSun = 109 x DEarth . (See overlay)
Or 1.3 million Earth volumes.
How massive? MSun = 330,000 MEarth .
How far? 1 AU = 1.5x108 km = 8.3 light mins (Pluto-5.5 lt hrs)
How bright? Power output at source = Luminosity,
L = 4 x 1026 watts. Enough power to cover surface with 100 watt tiny Christmas tree lights.
How bright at Earth? Solar Constant = 1,370 watts/m2.
Like 14 100 watt bulbs.
Content? See abundance overlay.
Energy transfer in the sun: (see drawing of layers)
1. Radiation: high energy gamma rays are absorbed and
remitted as multiple photons, degrading energy. It takes
3-10 million years for energy to leave the sun's surface.
Up until 2002, we thought we got 1/3 of the neutrinos expected. This was called the solar neutrino problem.
2. Conduction: kinetic energy transferred by collisions.
3. Convection: hot gas rises then sinks providing convection cells.
Source of Energy (Nuclear Fusion):
P-P Process: Protons must have enough energy to get close. This means 10 million degrees K (Kelvin = Centigrade + 273).
Dominates in stars less than 1.5 solar masses.
p + p --> D + positron + neutrino
p + D --> 3He + gamma ray
2 3He --> 4He + 2p
CNO Process: In stars above 1.5 solar masses there is recycled
Carbon, Nitrogen, and Oxygen which work as a catalyst for fusing protons into Helium 4. (See overlay.)
Spectrum:
Continuous spectrum with dark lines. Peak wavelength gives surface temperature T = 5700 K of photosphere. We can see into various depths by looking out at the limb, or sun's edge.
Sunspots:
1. Maximum every 11 years. Sun's magn. pole also flips every 11 years.
2. They migrate toward equator.
3. We know the have intensified magnetic fields by the amount lines are split apart by the Zeeman effect.
4. No sunspots from 1650-1715 AD--Maunder minimum.
5. They are associated with flares and prominences.
6. Babcock's dynamo theory utilizes differential rotation to explain the variations in sunspots.
7. The solar wind of electrons is increased during sunspot maximum and by solar flares.
Star Characteristics:
How far (R in parsecs)?
Distance to nearby star determined from stellar parallax, , (see overlay) which is ½ the maximum angular difference in position:
R (in parsecs) = 1/ ( in arc seconds)
1 parsec is the distance at which the parallax of a star is 1 arc second. Parallax method works for stars closer than about 100 parsecs. (1 parsec = 3.26 LY.)
How bright (L in watts)?
Luminosity at the source is determined from apparent brightness and distance (R).
Apparent magnitude (old way). We can see about 1,000 stars in Northern Hemisphere with naked eye. Hipparchus rated them from 1 to 6. A '1' is 2.52 x brighter than a '2', etc. We see things ranging in brightness from the sun at '-26' magnitude to the faintest objects seen at about '26' magnitude.
Flux (new 'apparent brightness'):
f (watts/m2) = L/4R2 = Power/unit area of sphere.
From R, the distance, we get L, the luminosity (watts of source).
How Big (r in meters)?
The Stephan-Boltzman Law gives the surface flux from surface temperature, T.
f(surface) = constant x T4 for a black body.
(Recall the black body spectrum provides T.)
Thus the radius of a star r comes from,
f(surface) = L/4r2.
Flow of ideas: parallax-->R, R & f -->L, L & T-->r.
Spectral Class (Color-Temperature Class):
Annie Jump Cannon (1912) classified dark lines for 200,000 stars!
O B A F G K M
<-----------------
T
BLUE RED
Subclasses: Sun is a G2V star.
A. 1-10 Spectral Subclass.
B. Luminosity Class I-V (I--supergiant, V--main sequence).
The Evolution of a Star:
Hertzsprung-Russell Diagram (1910): A plot of Luminosity vs Surface Temperature, T (see overlay). A one solar mass star like the sun goes through the stages of: protostar, main sequence, red giant, planetary nebula, white dwarf.
Multiple Star Systems:
Binaries:
1. Optical double--a false binary--two stars not bound together.
2. Spectroscopic--don't see separate stars, just separate spectra.
3. Eclipsing--one star eclipses another. Two dips--light curve.
4. Visual binary--actually seen as separate.
Mass Luminosity Relation: Mass determines evolution (Eddington): L = M3.5 (overlay). Mass yields Luminosity, and thus distance by r2 law of light.
Cepheid Variable Stars:
John Goodrick (1784) discovered Delta-Cephei.
Henrietta Leavit (1908)--Period Luminosity Relation:
(overlay). Stars varying in brightness with period 1-50 days have linear relation between period and luminosity. This gives luminosity and thus distance to stars even in other galaxies.
The Interstellar Medium:
1. Dust--recycled star material. Light undergoes to changes in
going through it (Trumpler 1930):
A. reddening--preferential scattering-blue light (why sky is blue).
B. absorption--this affects flux and measured distance.
2. Molecular Clouds--H2 molecules--dense MC are star formation regions (stellar nurseries like Orion Nebula).
Addition to Notes
Other Variable Stars:
1. Mira Variables--period over 50 days. 3 mos. to several years. Mira (Ceti Omricon) in Cetus, the Whale, varies by 6 magnitudes (2.5 each magn.) In 11 months. Egg-shaped distorted pulsation. M stars in giant phase 700 x solar diameter. Long Period Variables.
2. RR Lyrae variables--Short Period Variables--Cluster Variables--P=less than one day. Many in globular clusters with same mass and average brightness. 0.6 absolute magnitude (magnitude at 10 parsecs). Light Curve has distinctive shape with spikes. Core Helium burning--instability strip (Cepheids too).
Stellar Motion:
Proper motion: angular velocity
Transverse velocity: from distance
and proper motion.
Radial velocity: from Doppler shift--
v/c = /.
Space velocity: from transverse and
radial by Pythagorean Theorem.
C2 = A2 + B2.
Proper motion of most stars is very small. Exception: Barnard's Star
10.3"/year.
The Lives of Stars
Gestation, Birth, and Youth:
1. The womb: Stars are born in dense molecular clouds.
--The interstellar medium must be dense enough so H atoms can collide and form H2 molecules. This also is
facilitated on dust--for other molecules as well. It increases
gravitation enough for stars to form in reasonable time.
--Different sized clumps form stars of differing mass.
--Disk with central sphere (protostar) formed. Gravity heats by Helmholtz contraction. Disk forms solar system.
--Stability when gravity balances gas pressure (overlay). (Fully developed fetus)
--Star draws a womb of dust around it. It glows in the IR.
2. Birth: A star is born when its cores temperature reaches
10 million K. This happens for masses > 0.08 M(Sun).
--the star blasts away its womb of dust and shines.
--T Tauri Stars: variable brightness (like contractions).
Low mass stars just about to move to the main sequence.
3. Infancy:
--Jets of gas may heat the IS medium--Herbig Haro objects or YSOs. Bipolar outflow.
--Now on main sequence. .007 of core H will become energy in nuclear fusion by E = mc2.
--Star less than .08 M(sun): failed star or brown dwarf.
--Hot O and B stars form HII regions-Stormgren Spheres.
--Massive star formation triggers adjacent regions to become star formation regions. Shockwaves from ionization and supernovae bunch up material to form stars.
'Working Years'--Main Sequence--H burning phase.
Lasts 9 billion years for the Sun. Moves slightly up and
to the right in H-R diagram. As H in core is depleted, star
contracts slightly and Luminosity increases a little. He
has less gas pressure than H.
'Midlife Crisis'--Red Giant Phase: parallel 1 & 5 MO.
1. Stops burning H in the core, contracts, starts burning H in a shell around the core (Shell H-Burning). The heat expands the outer envelope of the star. It moves
Way up in the H-R diagram for a 1 MO star, stays at the same luminosity, but gets redder for a 5 MO star.
Mass loss as RG is as much as 10-6 MO/year!
2. The Red Giant contracts and Helium burns in Helium
flash with electron degeneracy holding up core in 1 MO star. It burns for 10 million yrs. in a 5 MO star on the horizontal branch with no degeneracy.
3. He burns to C by triple alpha process (see overlay).
In 5 MO star Carbon then burns to heavier elements.
4. Shell He-burning. He and H rekindles around core.
1 MO star expands to Red Giant again and 5 MO
redder and lower temp. (To right in H-R.) 5 MO or more undergoes thermal pulsations (Cepheids and RR Lyrae--instability strip)
'Retirement'
1. Stars starting with less than about 2 MO finish burning to carbon, become unstable as they burn H and He in a shell and shuck off a shell of 10-20% of their mass, becoming a planetary nebula, glowing because they are ionized by the hot UV core.
2. Stars with more than 2 MO burn to whatever element is the largest for their temperature.
3. In very large stars (over 10 MO), core burns to iron(Fe).
The s (slow) and r (rapid) process: elements heavier than Fe are formed by addition of neutrons and then beta decay. The s process adds one neutron at a time, the r process many at a time.
Ex. of s process: 114Cd + 1n --> 115Cd --> 115In + e- + .
'Death'
1. Supernova Type II: A star of over 2 solar masses burns to all it can, collapses as supporting radiation turns off, gets hot, produces neutrinos by combining
protons and electrons, and rebounds, and explodes.
Example: Supernova 1987A in Large Magellanic cloud detected by Ian Shelton--new star on plate.
2. End states of stars:
Remnant: End State: Supporting Pressure:
<1.3 MO White Dwarf Electron degeneracy
1.3 MO<M<3.0 MO Neutron Star Neutron
> 3.0 MO Black Hole None
3. Nova and Supernova Type I: A binary with a white dwarf and a red giant creates an explosion. Mass from the red giant is pulled onto the surface of the white dwarf. The heating creates an explosion: a
Supernova Type I, if the white dwarf is destroyed,
Nova if it is not (overlay). Supernovae type I are
'standard candles'--of same peak luminosity. A nova brightens by 100 to 1,000,000 times. A supernova brightens by about 100-150 million x.
4. White Dwarf: about earth-sized, held up by electron pressure. Fusion has ceased. Hot at first on surface--20,000 K then cool to black dwarf in billions of years. Chandrasekar Limit--white dwarfs form with remnant under 1.3 MO.
5. Neutron Star:
--Electrons squeezed into protons make neutrons.
--Gravity sufficient to make neutrons 'touch'.
--10's of km in diameter with some surface electrons.
--Cons. of angular momentum--rapid spin, strong magnetic fields and synchotron radio radiation as electrons are spun out along field lines.
--This radiation peaks in polar beams. As NS precesses, the beams may be detected as pulsars.
--Jocelyn Bell discovered the first pulsar in 1967.
It was at first thought to be a signal from an alien
civilization and had a period of about 1 s. One in
the Crab Nebula (former supernova 1054 AD)
BLACK HOLES
Laplace (1796) is usually given credit.
John Michell, 13 years earlier (1783), discovered that if matter were concentrated enough, Newton's Laws would give an escape velocity greater than light. Sun would be dark if squeezed to a ball 3 km in diameter.
Schwarzschild (~1920) did a calculation which showed Einstein's GTR predicted that a highly concentrated spherical mass would shrink to a point and have an event horizon around it beyond which nothing could escape (Vescape> c).
The Schwarzschild radius,
R(event horizon) = 3 km x mass (in solar masses).
Oppenheimer (~1940) demonstrated that a stellar remnant above 3 solar masses could not be held up by neutron pressure and would collapse further
Penrose (~1968) showed the GTR called for an eventual singularity (point mass) in the case of mass that large.
John Wheeler gave the 'black hole' its name.
Stellar mass black holes: only seen when material is falling in producing an accretion disk. This happens when, for example,
a star (originally bigger than about 5 solar masses) has a companion and draws in material from the other star. X-rays are
produced as the material heats as it fall in.
Cygnus X-1: first stellar mass black hole discovered by the Uhuru (means 'freedom' in Swahili) satellite in 1971. The gravity of the x ray object is somewhere between 6 and 20 solar masses.
Hawking (~1968) said that black holes radiate!
They are simple: they can have only mass, charge, & spin.
The 'no hair' theorem: they can have no fields along surface, like magnetic fields. Hair on a head must have a part or swirl, and black holes are too simple for that.
White hole: time reverse of a black hole. One way membrane 'out', BH is a one way membrane 'in'. Novikov (1964) suggested
Big Bang might have retarded cores (little Bang an example?)
Einstein-Rosen Bridge (1930's)--wormhole. Theory that a closed (massive) universe might have BH-->WH tunnels connected different places and times.
Penrose: energy may be extracted from ergosphere around rotating BH.
Fall into a BH might not be fatal:
1. If BH is large enough, event horizon is large and provides
little tidal force.
2. If BH is rotating fast enough you could enter wormhole.
3. Wormholes only exist in a massive universe.
4. You must have antimatter pasted on your spacecraft.
(Kip Thorne)
5. You must be prepared to travel in time or to another universe without returning.
Baby Universes: a closed universe with 1028 Joules of energy in a localized region can produce a baby universe. Its time is 'imaginary'.
Galactic cores and naked quasars: may be fed by black (or white) holes.
The Expanding Universe is sort of a white hole and will become sort of a black hole if it recontracts.
Star Clusters:
Open Clusters: less than 1,000 Population I stars-young, composed of recycled material with heavy elements. Not gravitationally bound.
Examples: The Pleiades and The Hyades.
Globular Clusters: thousands to millions of stars in a spherical bound group. Population II stars-old, made of primordial H and He. From 12-15 billion years old. Stars have small mass.
Cluster age: Determined by where the cluster is turning off the main sequence-the turnoff point.
The Galactocentric Perspective
The Milky Way:
Herschel 1800--The slab universe
Kapteyn 1900--The red blood cell universe
Harlow Shapley 1917--We are not at the center of the disk.
Globular clusters orbit galactic center, sun 2/3rds way out.
He used proper motions of Cepheids-->Distance (11 stars).
Shapley-Curtis debate 1920--Nebulae are within our island universe (Shapley). Nebulae may be other galaxies (Curtis).
Edwin Hubble 1923--distance to Andromeda galaxy found from
Cepheid Variable. 2.25 Mill. vs 100,000 LY--Milky way size.
Spiral arms: 21 cm radio radiation allows us to see through dust. Its Doppler shift tells us how arms are moving.
Galaxy rotates once every 225 million years (sun-240 km/s).
Differential rotation--spiral arms should wind up in 50 turns.
Galactic rotation curves don't obey Newton's Laws for the
visible matter-->dark matter (about 10 x the visible mass-much of it in halo).
Density wave theory: a gravity wave flows through galactic
disk, compressing, & causing star formation in its wake.
Origin: Top down vs bottom up vs hybrid vs White hole (?).
Age and metal content of stars in various regions confuse issue. Clusters: 1. Disk <7 Bill., 2. Gal. Cl., core, and halo 12-16 Bill. Core: Strong radio source in Sag. A at center--supermassive black or white hole? Intense IR and spherical shell of exp. gas.
Very dense with Pop. II stars--like elliptical galaxies, but with dust. Has core died down from a very active state? Quasars in early galactic cores give off much more energy.
Characteristics of Galaxies
Classification: The Hubble Tuning Fork
Elliptical: E0--E7 Spheroids, E0 is spherical, E7 least spherical.
Population II stars, little dust, almost no star formation.
Normal Spirals: Sa, Sb, Sc Sa is most tightly wound, Sc least.
Population I stars in disk, Pop. II in nucleus. Dust and star
formation in disk.
Barred Spirals: Sba, Sbb, Sbc Have bars across nucleus, Same
winding rules as normal spirals. Same content as normal.
Irregulars: No definite shape. Ex. Large and small Magellanic
clouds. Dominate universe by number, although generally smaller. Star formation, but less dust than disks.
Peculiar: (Pec) Have a definite form, but with peculiarities.
Radio jets or other strangeness.
Luminosity class: a subclassification, I is brightest, V least bright, like stars.
Galaxy Mass: from 1) Rotation curves, 2) Binaries, Clusters.
Disagreement-->missing mass--dark matter in galaxy, corona.
Distance: Standard candles--Cepheids, Supernova type Ia, standard galaxies like brightest spiral or Supergiant ellipticals in Cluster cores. If all else fails, Hubble's Law.
Hubble's Law: v = Ho d. Velocity from redshift is proportional to distance. Ho = 70 km/s/Mpc (Friedmann).
Diameter: from distance and angular diameter.
Luminosity: from distance and flux.
Mass/Luminosity Ratio: M/L tells us average nature of stars and dark matter.
Evolution? A mystery we will start to probe later.
Active Galactic Nuclei (AGN)
QUASARS: Radio Quasi-Stellar Objects. Maarten Schmidt
examined 3C273 (3C=Third Cambridge Catalog of Radio
sources) and found its distance from its redshift to be 2 billion light years--not a star, and L = 1040 watts--1,000 L (MW)!!
.8 to 14(?) Billion years--distance range. L = 1038-1042 watts.
Energy comes from a region solar system-sized. Radio Jets.
A thermal (synchotron) and non-thermal (black-body) continuous spectrum & broad (gas with varying speeds) lines.
Found to have stars around them (galaxies) in most cases.
Supermassive BH model suggests a billion solar masses by
Eddington Limit--Max M(BH) = L /30,000 (Solar Ms & Ls).
If larger mass, luminosity would blow away infalling material.
QSO's: Radio quiet Quasi-Stellar Objects.
ACTIVE GALAXIES: On average, seen at closer distances than QSOs. Some in nearby clusters.
Seyfert Galaxies: ~1037 watts, 1,000x dimmer than QSOs.
Type I--broad (narrow peak) and narrow emission lines.
Type II--just narrow emission lines. ).
Radio Galaxies: Less luminous than Quasars. Often elliptical
or peculiar (collision-stimulated?).
Blazars: variable quasarlike radio sources (Exs. BL Lacertae--
3C279 Burst in 1937 and 1943)
Unified Model: drawn on board. AGN May be same thing seen from different angles.
Naked Quasars: no stars around them--NOT AGN. W. Hole?
Cosmological Terminology:
Cosmology: the study of the large scale structure and evolution of the
universe.
Homogeneity: the claim the universe has the same density in all locations at the largest scale.
Isotropy: the claim the universe looks the same in all directions.
Pre 1998 Cosmology--ignoring cosmological constant:
Friedmann 1920 (utilizing Einstein's General Theory):
Critical Density: About 10-29 g/cc. The density below which a universe sans cosmological constant will expand forever.
Closed Universe: a universe with more than the critical density. Like a
spherical surface-finite.
Open Universe: a universe with less than critical density-saddle-shaped, infinite.
Flat Universe: a universe with exactly critical density. Required in the
inflationary theory of the universe (Guth 1980). Inflation is thought to be required to explain:
1. The tuning of the expansion needed to produce the smoothness of the universe.
2. The uniformity of the cosmic microwave background at distances
too great to have been in contact without the universe having expanded greater than the speed of light for a brief time.
3. No detection of cosmological magnetic monopoles.
4. The production of the lumpy structure of the universe necessary to
produce clusters, galaxies, and stars. Scale free lumpiness.
Proofs of the Hot Big Bang (of Georges LeMaitre):
1. The red shift of distant galaxies.
2. The cosmic microwave background. Penzias and Wilson 1976.
A black body curve at T = 2.7 K results from electrons combining with protons to make hydrogen. Ultraviolet stretched to microwave
with the expanding universe. This has small lumps in different directions of about 1 part in 10,000 indicating early inflation.
3. Nucleosynthesis-Burbidge, Fowler, and Hoyle in 1960 calculated
Big Bang made 75% He, 25% He-observed in unrecycled material.
Post-1998 Cosmology-A funny energy in space
At the present epoch the velocity of receding galaxies is given by Hubble's Law: v = Ho d , where Ho is the Hubble constant.
1. This holds only for galaxies at moderately low distances.
2. In actuality, the straight line of Hubble's law curves gently downward at greater distances as indicated by supernova Ia measurements of explosions up to about 10 billion years ago (Perlmutter's and Schmidt's groups -post 1998).
a) The velocities are given by the redshifts of the galaxies they are in. b) The distances are given by standard luminosity of supernovae Ia.
3. This means the universal expansion is accelerating. It will expand forever in such a way that it implies
a) The mass in the universe is not sufficient to turn the expansion
around, even with dark matter included,
b) There is a funny energy in space driving the acceleration like
a compressed sponge when released. If Einstein's General Theory
holds, this energy may be in the form of Einstein's cosmological
constant, . This outward force is ever-renewed in such a theory.
It may also be a time varying component called quintessence.
4. There is some evidence indicating the universe is flat-the Cosmic microwave background radiation has ripples which fit. However, the standard inflationary theory, which describes an early rapid universal expansion for a fraction of a second, may not fit the ripples exactly.
Number of Intelligent Civilizations--
The Drake Equation
Nic = Ric Lic
Number = Rate of Formation x Lifetime
Like candles lit every minute with each lit for five minutes--there will always be 5 candles lit.
Ric = RsPpPeNePlPi
Rs = avg. rate of star formation
Pp = probability planets will form around star
Pe = prob. star will shine time for life to form
Ne = Number of planets/star with right Temp.
Pl = probability stars ecosphere will develop life
Pi = probability that evolution will lead to i-life
Life On Other Worlds?
What is life? Reproduction, mutation, and evolution--Zeilik. Do you agree?
Mutation: Cosmic rays and errors change DNA.
Evolution: natural selection. Survival of the fittest?--doesn't quite work. Mutations
Which can reproduce--latest idea.
Life Field: a field which holds the pattern for the organization of a life form.
Kirlian Photography--high frequency electromagnetic stimulation--shows pattern of life form. Phantom leaf and phantom limb, salamander's tail.
Aura--magnetism measured around body, photographable--differing colors for
different individuals.
Where does this pattern come from?
Chemical Basis: Need proteins and nucleic acids. Made of N C H O ('nacho')
Ammonia + methane + Hydrogen + Water + Lightning-->amino acids + fats
(Lava--hot silica and UV work too) Stanley Miller and Harold Urey--1952
Amino acids-->proteins (enzymes, which control cell function are example)
by random linkage.
4 Bases-->nucleic acids (Ex. DNA 4.5 billion bits of information control enzymes. Deoxyribonucleic acid.
Happened in hotsprings along midocean ridges. Meteoritic impacts and volcanism early on would have destroyed life. Amino acids linked and chemical evolution
allowed some forms to dominate over others (depends on mis in primordial soup) OR life came from meteorites and/or comets (formadehyde, HCN-->aminos) Some life related molecules found in meteorites.
1 Billion years for life to evolve--Australian bacteria and algae fossils--3.5 Billion years old.
Random production of DNA is highly improbable.
Life is energy, information, form, and reproduction.