Chapter 10: Sacred Black Flashcards
Carl Sagan, Pale Blue Dot, 129b
What colors make up the visible light of the sun?
What are the given wavelengths for each color?
Violet Blue Green Yellow Orange Red
Violet/Blue: Shortest Wavelengths
Orange/Red: Longest Wavelengths
Carl Sagan, Pale Blue Dot, 129
Q:Why is the sky blue during the day time and not the night?
A: During the Day time sunlight is bouncing off the air around and above us
During the night time no sufficiently intense source of light is to be reflected off the air
Carl Sagan, Pale Blue Dot, 129c
What is a wavelength?
What wavelength length/ size scatter most/least efficiently in atmosphere?
A wavelength is the distance from crest to crest as the wave travels through air or space
Sun light wavelengths closer to the size of air molecules* scatter more efficiently in the atmosphere
Sun light wavelengths longer than the size of Earth’s air molecules* (nitrogen/oxygen) scatter less efficiently in earth
Carl Sagan, Pale Blue Dot, 131
What can color the sky ?
the blue of Earth’s doesn’t depend on Earth’s atmospheric makeup( NO2/O) as long as the air doesn’t ABSORB** visible light
*Oxides of Nitrogen absorb light, which is ironically made up of oxygen and nitrogen
Some chemical properties absorb different colors than others
Carl Sagan, Pale Blue Dot, 131
What is the size of a molecule?
Size of a Molecule
100 hundred millionth of a centimeter
Carl Sagan, Pale Blue Dot, 130
Q: why is the sunset red/orange?
A: after all the blue (short wavelengths) is scattered away by occultation of the sun, the red/orange (long wavelengths) is what remains not scattered. The longer the distance “light travels” (the slant path) through the Earth’s atmosphere, the longer the wavelength(color) is needed to remain visible.
Carl Sagan, Pale Blue Dot, 130
Q: 1) why is the sun yellow at noontime
2)Red/Orange at sundown/sunrise?
A: 1) Partly because the sun emits more yellow light than others and partly because, even with the Sun overhead, some blue light is scattered out of the sunbeams by the Earth’s atmosphere.
2)the leftover light they hasn't scattered is longer in wavelength(red/oranges), the residue of Sun light
Carl Sagan, Pale Blue Dot, 131
What color is the sky on a planet that has no atmosphere?
if the planet has no atmosphere, the skies are always black, even at noon. A zero atmosphere neither scatters nor absorbs Sunlight that travels along the way. A bodily structure must have enough gravity to hold an atmosphere.
Carl Sagan, Pale Blue Dot, 139
What are characteristics of Venus’s atmosphere?
Venus
• 90x more air than Earth
• Atmosphere mainly CO2
(Carbon dioxide)*
• Sky color Yellow*/Orange*
- CO2 doesn’t absorb light
- Yellow because sulfur in high clouds stains it that way, Droplets of Sulfuric Acid (pg 139)
- the thickness of atmosphere bounces off all shorter wavelengths, and what filters through is
Carl Sagan, Pale Blue Dot, 133
What are characteristics of Mars Atmosphere?
Mars
•much thinner atmosphere than
Earth
• Sky color Ochre/Pink
• Press Release Sky pic Blue
because Viking Analysts*
balance pic's monochrome
images* to match Earth's color
balance. The composite was
then adjusted in accordance
to color calibration standards
*they weren’t Planetary astronomers
*3 monochrome images(red, green, blue lights) are balanced ( intensity, for example) in the TVs and video projection systems to yield “right
color(Earth sky = blue).”
Carl Sagan, Pale Blue Dot, 135
What are some peculiarities of Black Skies?
All worlds with nonblack skies have atmospheres but not all black skies* have no atmospheres*
Carl Sagan, Pale Blue Dot, 134
What planets have black skies located from the vantage point of the surface?
Jupiter*, Saturn, Uranus, and Neptune have thick enough atmospheres that no light can penetrate it sufficiently color the sky from a surface vantage point.
Carl Sagan, Pale Blue Dot, 135
However, depending on where one is at in Jupiter’s atmosphere, a sky region can shaded a different color
High Altitude
-composed of ammonia ice
particles
- Sky color is black
Farther Down
-unknown composition
-Sky color: blue
-Clouds: shades of yel/bro
Even Farther Down
-composition unstated
-Sky color: red/brown
-Cloud: Varying Thickness
thin, patch of blueCarl Sagan, Pale Blue Dot, 135
What are Uranus’s and Neptune’s
atmospheric makeup?
Uranus/Neptune
•Helium/Hydrogen/
MethaneRich
•Long paths of methane absorb yellow/esp.red light and green/ blue filters through.
Carl Sagan, Pale Blue Dot, 136
What is Mar’s surface pressure?
Mars
•Surface pressure is approx
the altitude of 100,000ft
on Earth
