Exam 1 review Flashcards
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Layers of Earth
Crust–> mantle –> core
Electromagnetic Radiation
Transmission of energy through space without physical connection by carrying waves of electric and magnetic fields.
Radar Ranging
Uses radar signals to measure the distance of objects in the solar system, like echolocation
Adaptive optics
Mirror shape is deformed by a computer while image is viewed to counteract atmospheric turbulence
Electromagnetic Waves
Waves that do not need a medium to propagate and that travel with velocity v=c
Electromagnetic Spectrum
Radio–>Microwave–>Infrared–>Visible Light–>UltraViolet–>X-rays–>Gamma Rays
Prime focus in a telescope
the point where the light is focused to in a telescope
The celestial sphere
the tool that we use to localize celestial objects, as if the stars
wereturning around us
Amplitude
Maximum departure of a wave from the undisturbed state
Eccentricity
how “oval” the ellipse is
Closer to zero –> circle
How long ago did the Solar system form
About 4.5 Billion Years ago
solar day
rotation period of the Earth with respect to the sun (3.9 minutes longer than the sidereal day)
What does the wavelength of electromagnetic radiation depend on?
Temperature
Frequency
Number of crests passing a given point per unit time
Celestial Equator
above the Earth’s equator on the celestial sphere
Wavelength
Number of meters needed for the wave to repeat itself at a given moment in time
Zodiac
the 12 constellations the Sun moves through during the year
Magnetosphere
Region around Earth containing a magnetic field where charged particles from the solar wind are trapped
Equator
a great circle on Earth’s surface, halfway between the North and South Poles.
Continuous spectrum
The whole rainbow
Tycho Brahe
Made very careful measurements of planetary motion
He did not have the ability to analyze these measurements. Kepler was the one that was able to analyze
Refraction
bending of light from a source
Protoplanets
Objects that eventually turn into planets
Condensation theory
nebula theory with dust cooling clouds, causing hot stuff to clump together
Sidereal year
365.256 solar days
time for Earth to orbit once around the sun, relative to fixed stars, thus the sidereal year follows constellations
Summer (winter) solstice
Most northern point of the sun on the celestial sphere, days (nights) are longer in duration
Latitude
north or south location
ecliptic tilt
Due to the tilt of Earth’s rotational axis relative to the orbital plane around the sun
Black Body Radiation
an object that does not reflect or scatter any radiation, but absorbs and emits all wavelengths
Perihelion
Point where a planet is closest to the sun and moves the fastest
Kepler’s third law
Square of period of planet’s orbit is proportional to cube of semi-major axis
Eclipses
When the moon and the sun have the same size in the sky
Lunar eclipse- Sun, Earth, Moon
Solar eclipse- Sun, Moon, Earth
“packet” of electromagnetic radiation
Photon
Mechanical Waves
Waves that are governed by Newtons laws and that exist within a medium
Infrared Astronomy
Penetrates stellar dust and atmospheric clouds and can image where visible radiation is blocked
Standard Time
divides the world into 24 time zones
What causes seasons
tilt of the Earth
angle of sunlight makes it less efficient in heating the surface of the Earth
Jovian/Giant planets
4 outer planets, gaseous, large
Eratosthenes
Greek astrologist who made the first measurement of the Earth’s diameter in 200 BCE (40,000km, only 70 km off)
How does electromagnetic radiation happen in atoms
the electrons get excited, then jump up an orbital, once they lose enough energy they fall down the orbital, it releases a photon.
Prime Meridian
Runs through Greenwich England, line of longitude
Earth’s tilt
23.5 degrees
Gregorian Calendar
Correct to about 3300 years, what we use today
Astronomical Unit (AU)
distance between the earth and the sun
(about 94 million miles)
Constellation
Bright stars that are grouped together
Gamma ray astronomy
cannot be focused at all, from the most violent events in the universe
Why don’t eclipses happen every month
The Earth and Moon’s orbit are not in the same plane
Angular Momentum
measure of the rotation of a body as it revolves around some fixed point (keplers second law is a consequence)
Stefan-Boltzman Law
The energy flux from a blackbody at temperature T is proportional to the fourth power of its absolute temperature. Then scaled by a constant
Synchronous rotation
when a body rotates once on its axis in the same time it takes to compete a revolution (the Moon)
Light behaves as…
a wave and a particle
Longitude
Meridian, specifies east-west location.
general force of attraction
product of the masses divided by the square of the distance between them scaled by the gravitational constant
Gravity
what is the relationship betweein light strength and distance
light gets weaker as it gets farther from the source as an inverse square
Newton’s Third Law
equal and opposite reactions
Jovian planets are characterized by their…
composition (mostly hydrogen and helium)
Kepler’s Second Law
The imaginary line connecting Sun and planet sweeps out equal areas in equal times
Discovery of Neptune
Through abnormalities in the orbit of Uranus
the first to build a telescope and use it to test his ideas
the first to support his theories with experiments
Galileo
Wien’s Law
The frequency of the emitted radiation is inversely dependent on the temperature. Then scaled by a constant
Astrology
Used zodiacs to predict attributes of people, there is no evidence that natal astrology has any predictive power
How far can we see?
slightly past the horizon due to the bending of light in the atmosphere (refraction)
Period
Number of seconds needed for a wave to repeat itself at some point in time
Lunar phases
Waxing- the lit portion is growing
Waning- the lit portion is shrinking
Crescent- less than half of the lunar disk is visible
Gibbous- More than hale of the lunar disk is visible
Ultraviolet Astronomy
must be done from space
Ecliptic
The apparent path of the sun on the celestial sphere
Advantages of Radio Astronomy
- Can observe 24 hours a day
- Weather does not interfere
- Different frequency of light viewed, totally different information
Comet structure
nucleus–>Coma–>Hydrogen envelope–>Ion tail–> dust tail
Synodic Month
29.5 days
time for the moon to complete a full cycle of phases
Parsec
3.26 light years
Sidereal month
27.3 days
time it takes the Moon to rotate around the Earth
Tidal Forces
Moon and Sun’s pull on the Earth causes the water level to rise
Aphelion
Point where a planet is the farthest away from the sun and moves the slowest
Nebular theory
the planets form from a spinning disk, not enough to explain planet formation
International Date Line
a geographical line that marks the official change of day
X-ray Astronomy
Must be in space, does not reflect off of mirrors but can be focused
Light Year (ly)
The distance that light travels in a year
(about 6x10^12 miles)
Reflection
mirror
Heliocentric model
Planets orbit in circles around the sun
Aristarchus of Samos proposed that all planets revolved around the Sun and that Earth rotates (his ideas were ignored)
Newton’s Second Law
F = ma
Geocentric Model
Earth lay at the center of the universe (wrong)
A Great Circle
any circle on the surface of a sphere whose center is at the center of the sphere
Apparent Solar Time
time as reckoned by the actual position of the sun in the sky (sundail)
worked on the laws of motion, gravity, optics, and mathematics
Isaac Newton
Hipparchus
Found the precession of Earth’s axis
Newton’s First Law
Inertia
Horizon
The line where the dome meets the Earth is the horizon
Emission Spectrum
Solely the colors that are radiated from the materials that exist in the studied object
Spectrometer
Used to tell what type of material is in an object by bending the light into a spectrum
Tropical Year
365.242 days
our calendar year is the time interval between vernal equinoxes
Julian Calendar
introduced by Julis Ceaser, approximated that the year is 365.25 days, not what we use
Escape speed
The speed needed to escape Earth’s gravitational pull
North Celestial pole
Above the North Pole on the Celestial Sphere
Moon formation
Mars sized object hit Earth, chunk flew off, became the Moon
Claudius
Proposed a model for the solar system
Uranus’ Rotational Axis
lies almost within the plane of its orbit
Zenith
The top of the dome, just above your head
Active optics
Control mirrors based on temperature and orientation
Sidereal Day
rotation period of the Earth with respect to the stars
Limitations to observation
Atmosphere- filters light
Cities- light pollution
Air- unsteady, air turbulence, “bad seeing”
Which one is longer, Tropical Year or Sidereal Year
Sidereal year, due to the precession of Earth’s axis
Planetesimals
Objects the size of small moons, gravity strong enough to attract matter
Vernal (autumnal) equinox
When the sun crosses the celestial equator, day and night are of equal duration. spring(fall)
Terrestrial Planets
4 inner planets, rocky, small
Mean Solar Time
Based on the average value of the solar day over the course of a year (exactly 24 hours)
Kepler’s first law
Planetary orbits are ellipses, with the Sun at one focus
Earth composition
Primarily iron, silicon, and oxygen (heavy stuff)
