06 November 2007
Aliens and Alien Societies
Science Fiction vs. Fantasy:: Fantasy’s events are pretend and happen only in the story; Science Fiction tryies to create worlds/futures that could exist
-both deal with the impossible
-sci-fi seems far out but is based on real principles
-if it can’t be proved 100% impossible, then it could be used for sci-fi
ASTRONOMY
Scientific Notation: 10^4 = 1 with 4 zeros after it
Wavelengths - (especially those seen in infrared, visible light, ultraviolet and x-rays) are expressed in Angstrom units (1A = 10^-8 = 10^-10m)
AU (astronomical unit) - distances within in the solar system (1AU = the mean radius of the Earth’s orbit)
Light Year (c) - 186,000 mi/sec = 9.46x10^15m = 5.87x10^12 miles
Parsec (pc) - parallax second = simplest method for measuring distances. 1pc = 3.26 LY
0 Kelvin - absolute zero, water freezes at 273K = 0C
Star Brightness is measured in magnitudes (lower number = brighter)
-A Difference of 1 magnitude is equivalent to a brightness ratio of 2.512 (5th Root of 100) e.g. 1.3 magnitude = 2.512x brighter as 2.3 magnitude and 100x brighter than 6.3 magnitude
--Negative Magnitude is brighter;: 100x brighter than 1.3= -3.7 (1.3-5)
--Apparent Magnitude (seeable by human eyes) = Negative number +6 (depends on distance)
Spectroscope - tells you how much light the source is producing at each wavelength (frequenies)
Wavelength - a “continuous spectrum”
Heat (from cold to hot):: None---Red---Yellow---White---none---bluish
-Light is absorbed (absorption spectrum) only at certain wavelengths, determined by its atomic/molecular structure
Dopplar Effect - apparent change in frequency and wavelength caused by motion of the source toward or away from the observer i.e. a galaxy (farther away=moving faster)= Hubble’s Law
F=GMm/r^2 - gravitational force between two bodies is proportional to the product of their masses, and inversely proportional to the square distance between them, where:
G - Universal gravitational constant
M&m - Masses
R - radius
- intergalactic > interstellar
- our nearest “neighbor” galaxies are the Magellic Clouds, more than 100,000 light years away; similar galaxies like ours are a couple million light years away
Star Type Temperature (K) Colour Luminosity Time on M. Sequence (star life span)
O 25k+ blue >30k <8x10^6
B 10-25k blue 100-300k 8x10^6 -- 4x10^8
A 8-10k blue 5-100 4x10^8 -- 4x10^9
F 6-8k blue-white 1.2-4.8 4x10^9 -- 1x10^10
G 5-6k yellow-white 0.4-1.2 1.1x10^10 -- 42.7x10^9
K 3.7-5k orange-red <0.1-3.5 2.8x10^10-~4x10^11
M <3,700 red <0.1 >10^11
-A star goes down to red then can recharge, OR, neutrons condense, spin, turn into a Neuron Star, turn into a Pulsar (because of rapid spinning, OR, (black hole) collapse to such a high density that light cannot escape
-Old stars eject outter layers into space
Supernova - extremely violent explosion that ends a star…temporarily becomes brighter than the galaxy
Superjovian - 10-15x larger than Jupiter, tighter atmosphere, spins faster
Jovian - Jupiter-Saturn size, thick atmostphere
Subjovian - Uranus-Neptune size, smaller mass, higher density, not much hydrogen, helium, higher concentration of heavier elements
Super Terrestrial - 8x Earth’s mass, 2x surface gravity, denser atmosphere
Terrestrial - Earth--Venus size, 100x Earth’s surface pressure -- varies
Sub Terrestrial - Mercury-Mars-Moon size, rocky, little or no atmosphere
For a planet to habitable, its star (eg our sun) must be F5-K5
-both deal with the impossible
-sci-fi seems far out but is based on real principles
-if it can’t be proved 100% impossible, then it could be used for sci-fi
ASTRONOMY
Scientific Notation: 10^4 = 1 with 4 zeros after it
Wavelengths - (especially those seen in infrared, visible light, ultraviolet and x-rays) are expressed in Angstrom units (1A = 10^-8 = 10^-10m)
AU (astronomical unit) - distances within in the solar system (1AU = the mean radius of the Earth’s orbit)
Light Year (c) - 186,000 mi/sec = 9.46x10^15m = 5.87x10^12 miles
Parsec (pc) - parallax second = simplest method for measuring distances. 1pc = 3.26 LY
0 Kelvin - absolute zero, water freezes at 273K = 0C
Star Brightness is measured in magnitudes (lower number = brighter)
-A Difference of 1 magnitude is equivalent to a brightness ratio of 2.512 (5th Root of 100) e.g. 1.3 magnitude = 2.512x brighter as 2.3 magnitude and 100x brighter than 6.3 magnitude
--Negative Magnitude is brighter;: 100x brighter than 1.3= -3.7 (1.3-5)
--Apparent Magnitude (seeable by human eyes) = Negative number +6 (depends on distance)
Spectroscope - tells you how much light the source is producing at each wavelength (frequenies)
Wavelength - a “continuous spectrum”
Heat (from cold to hot):: None---Red---Yellow---White---none---bluish
-Light is absorbed (absorption spectrum) only at certain wavelengths, determined by its atomic/molecular structure
Dopplar Effect - apparent change in frequency and wavelength caused by motion of the source toward or away from the observer i.e. a galaxy (farther away=moving faster)= Hubble’s Law
F=GMm/r^2 - gravitational force between two bodies is proportional to the product of their masses, and inversely proportional to the square distance between them, where:
G - Universal gravitational constant
M&m - Masses
R - radius
- intergalactic > interstellar
- our nearest “neighbor” galaxies are the Magellic Clouds, more than 100,000 light years away; similar galaxies like ours are a couple million light years away
Star Type Temperature (K) Colour Luminosity Time on M. Sequence (star life span)
O 25k+ blue >30k <8x10^6
B 10-25k blue 100-300k 8x10^6 -- 4x10^8
A 8-10k blue 5-100 4x10^8 -- 4x10^9
F 6-8k blue-white 1.2-4.8 4x10^9 -- 1x10^10
G 5-6k yellow-white 0.4-1.2 1.1x10^10 -- 42.7x10^9
K 3.7-5k orange-red <0.1-3.5 2.8x10^10-~4x10^11
M <3,700 red <0.1 >10^11
-A star goes down to red then can recharge, OR, neutrons condense, spin, turn into a Neuron Star, turn into a Pulsar (because of rapid spinning, OR, (black hole) collapse to such a high density that light cannot escape
-Old stars eject outter layers into space
Supernova - extremely violent explosion that ends a star…temporarily becomes brighter than the galaxy
Superjovian - 10-15x larger than Jupiter, tighter atmosphere, spins faster
Jovian - Jupiter-Saturn size, thick atmostphere
Subjovian - Uranus-Neptune size, smaller mass, higher density, not much hydrogen, helium, higher concentration of heavier elements
Super Terrestrial - 8x Earth’s mass, 2x surface gravity, denser atmosphere
Terrestrial - Earth--Venus size, 100x Earth’s surface pressure -- varies
Sub Terrestrial - Mercury-Mars-Moon size, rocky, little or no atmosphere
For a planet to habitable, its star (eg our sun) must be F5-K5
recorded at 00:27
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