Astronomy Exam 1 Flashcards
Stars appear to be fixed in _______ that surrounds the Earth
spherical shell (the celestial sphere)
A coordinate system that divides the celestial sphere
Equatorial system of location
The angular distance north or south of the celestial equator
Declination
The angular distance measured eastward along the celestial equator from the position of the vernal equinox
Right ascension
the time interval from one noon to the next- about 24 hours- measurement for rotation
Mean solar day
turning, or spinning, of a body on its axis
rotation
the time it takes for Earth to make one complete rotation (360°) with respect to a star other than the Sun – 23 hours, 56 minutes, 4 seconds
Sidereal day
The motion of a body, such as a planet or moon, along a path around some point in space
revolution
Earth’s orbit is _____
eliptical
Earth is closest to the Sun (perihelion) in _____
January
Earth is farthest form the Sun (aphelion) in ______
July
Direction in which Earth’s axis points continually changes- very slow Earth movement
Precession
Caused by Earth’s changing orientation to the Sunp Axis is inclined 23.5 degree and always points in the same direction
Seasons
-June 21-22- Sun’s vertical rays are located at the tropic of cancer
-the noontime Sun reaches its highest point of the year
-longest day of the year
Summer solstice
-December 21-22- Sun’s vertical rays are located at the Tropic of Capricorn
-The Sun crosses the meridian 23.5 degrees lower in alt. than the celestial equator
-sunset occurs at its farthest point south of due west for the year
-the noontime Sun casts the longest shadows
Winter Solstice
-September 22–23- Sun’s vertical rays are located at the Equator (0° latitude)
Autumnal equinox
March 21–22- Sun’s vertical rays are located at the Equator (0° latitude)
Spring (vernal) equinox
– Cycle of Moon through its phases
– 29.5 days
– Basis of first Roman calendar
– Apparent period of Moon’s revolution around Earth
Synodic Month
– True period of Moon’s revolution around Earth
– 27.3 days
sidereal month
When viewed from above the North Pole, the Moon orbits Earth in a _______ (eastward) direction
Counterclockwise
T/F The relative positions of the Sun, Earth, and Moon constantly change
True
- Moon moves in a line directly between Earth and the Sun
– Can only occur during the new-Moon phase
Solar Eclipse
– Moon moves within the shadow of Earth
– Only occurs during the full-Moon phase
Lunar Eclipse
All forms of radiation travel at
186,000 miles (300,000 kilometers) per second
Radio waves have ______ wavelengths
longer
gamma rays have ______ wavelengths
shorter
The apparent change in wavelength of radiation caused by the relative motions of the source and observer
Doppler Effect
Wavelength is longer
increasing distance
wavelength is shorter
decreasing distance
The study of the properties of the light that depend on wavelength
Spectroscopy
the light pattern produced by passing light through a prism, which spreads out the various wavelengths
spectrum/spectra
Produced by an incandescent solid, liquid, or high pressure gas- Uninterrupted band of color
Continuous Spectrum
Produced when white light is passed through a comparatively cool, low pressure gas
* Appears as a continuous spectrum but with dark lines running through it
- Most stars have it
Dark-Line (absorption) spectrum
Produced by a hot (incandescent) gas under low pressure
* Appears as a series of bright lines of particular wavelengths depending on the gas that produced them
Bright-Line (emission) spectrum
Was the first Greek to profess a Sun-centered, or heliocentric, universe
Aristarchus
– Concluded Earth was a planet
– Constructed a model of the solar system that put the Sun at the center, but he used circular orbits for the planets
– Ushered out old astronomy
Nicolaus Copernicus
– Supported Copernican theory
– Used experimental data
– Constructed an astronomical telescope in 1609
* Four large moons of Jupiter
* Planets appeared as disks
* Phases of Venus
* Features on the Moon
* Sunspots
Galileo Galilei
– Ushered in new astronomy
– Planets revolve around the Sun
Johannes Kepler
Orbits of the planets are elliptical
Keplers First Law
Planets revolve around the Sun at varying speed
Keplers Second Law
There is a proportional relation between a planet’s orbital period and its distance to the Sun (measured in astronomical units (AU’s) – one AU averages about 150 million kilometers, or 93 million miles)
P^2 = a^3
P= Earth years
a= astronomical units
Keplers Third Law
Laws of universal gravitation
Sir Isaac Newton
The law of Inertia
Newtons first law
The force law- acceleration is driectly proportions to the net force acting on it and is inversely proportional to its mass
Newtons second law
The law fo action and reaction- Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first object.
Newtons third law
– Mercury, Venus, Earth, and Mars
– Small, dense, rocky
– Large cores of iron and nickel
– Low escape velocities
Terrestrial planets
– Jupiter, Saturn, Uranus, and Neptune
– Large, low density, gaseous
– Massive
– Thick atmospheres composed of hydrogen, helium, methane, and ammonia
– High escape velocities
Jovian planets
Earth’s relatively thin, rocky outer skin
Crust
less dense, many rock types- granite
continental crust
dense, basaltic rock
oceanic crust
– Solid, rocky shell
– More than 82 percent of Earth’s volume
Mantle
entire crust and uppermost mantle
lithosphere
very hot, strengthens with depth
lower mantle
iron-nickel alloy
core
- Liquid layer
- Earth’s magnetic field
outer core
solid
inner core
– Bottom layer
– Temperature decreases with altitude – called the environmental lapse rate
* 6.5°C per kilometer (average)
* 3.5°F per 1000 feet (average)
– Thickness varies – average height is 12 km
– Outer boundary is named the tropopause
Troposphere
– About 12 km to 50 km
– Temperature increases at top
- contains the ozone
– Outer boundary is named the stratopause
Stratosphere
– About 50 km to 80 km
– Temperature decreases
– Outer boundary is named the mesopause
Mesosphere
– No well-defined upper limit
– Fraction of atmosphere’s mass
– Gases moving at high speeds
thermosphere
Plates pull apart
divergent
plates move together
convergent
plates slide past each other
transform fault
- Dark regions
- Fairly smooth lowlands
- Originated from asteroid impacts and lava flooding the surface
Maria
– Bright, densely cratered regions
– Make up most of the Moon
– Make up all of the “back” side of the Moon
– Older than maria
Highlands
– Most are produced by an impact from a meteoroid which
produces
* Ejecta
* Occasional rays
Craters
– Covers all lunar terrains
– Gray, unconsolidated debris
– Composed of
* Igneous rocks
* Breccia
* Glass beads
* Fine lunar dust
– “Soil-like” layer produced by meteoric bombardment
Lunar Regolith
Blue light has
higher energy
Red light has
less energy
Number of Waves per second
frequency
What phase occurs when the moon is between the earth and the sun
New moon
A measurement of how far light travels
light years
Where on Earth can you observe all the stars in the sky over an entire year?
Equator
Where on Earth would you be if Polaris were directly overhead?
north pole
Seasons on Earth are primarily caused by
the tilt of the Earth’s rotational axis
Where would you be if the Sun sets for six continuous months, beginning about September 23rd?
north pole
Where would you be if the Sun passes directly overhead on December 21st
Tropic of Capricorn
-rises at about noon
-it is the half moon of the evening sky
-it is highest in the sky at sunset
-it occurs about a week after the new Moon
First Quarter Moon
-Visible near western horizon about an hour after sunset
-sets 2-3 hours after the sun sets
waxing crescent moon
-visible near eastern horizon just before sunrise
-occurs about 3 days before new moon
waning crescent moon
-rises at about the time the sun sets
-occurs 14 days after the new moon
-visible due south at midnight
full moon
What conditions are necessary for a total solar eclipse?
New Moon on ecliptic near perigee
If you throw a rock into a pond, it creates a wave in the water. What is responsible for creating an electromagnetic wave?
A vibrating charged particle
The wave amplitudes are directed _______ to the direction of wave motion
perpendicular
Energy and information flows _______ to the direction of wave motion
parallel
What is constant for all types of Electromagnetic radiation in a vacuum
Velocity
A hot summer day might be 100
ice cream is stored in a freezer at 26
Farenheight
water boils into gas phase at 373.15
the coldest temp is 0
kelvin
liquid water boils at 100
water freezes into ice at 0
a typical room temp is 24
Celcius
Compared to optical telescopes, radio telescopes are built large because
radio photons don’t carry much energy
What are two advantages of large scopes over smaller ones?
large telescopes have more light gather power and better resolution
The Ptolemaic model of the universe
explained and predicted the motions of the planets with deferents and epicycles.
Scientists today do not accept the Ptolemaic model because
it was too complicated, compared to Copernicus’ heliocentric model
