General Astronomy Chapters 1-6 Flashcards
What is Astronomy?
Study of objects beyond earths atmosphere
What is science?
The method by which we UNDERSTAND how things work
Proving hypothesis true
An infinite amount of experiments
proving hypothesis false
it takes one experiment
Distance in Astronomy
kilometers
astronomical units
light years
parsecs
Scientific notation
Count zeros
Constellations
The patch of sky that gets the name, rather than the stars themselves
Asterism
A subset of stars that form a widely recognized shape
Celestial Sphere
Assumes all stars no matter the distance are projected onto a sphere around the earth
Horizon
Where the dome of the sky you can see meets the ground from your point of view
Zenith
The point above your head
Nadir
The point below your feet
Celestial equator
The projection of the earth’s equator into space
North celestial pole
The projection of the earth’s geographic north point into space
South celestial pole
The projection of the earth’s geographic south point into space
Altitude
The angle height of the north star (polaris) above the horizon
Sky at the north pole?
North star will appear to not move because it is center of earths axis
Archaeastronomy
The study of how people in the past understood the phenomena in the sky and the role it played in their cultures
Origin of oldest written constellations
Ancient Egyptian hyroglyphics
Astrology
A pseudoscience
Principles of science
Requires testing and verifiable ideas
Why did Aristotle believe the earth was round?
- the circular shadow of earth during a lunar eclipse
- if you change your location on earth you see different stars
How did ancient greeks know the approximate size of the earth?
Eratosthenes used geometry and trigonometry to find the earth’s radius.
Who discovered earth’s tilt?
Hipparchus by cataloging stars and their brightness
Ptolemy’s model/Geocentric model
The earth is the most important, therefore the center of everything…WRONG
Nicolaus Copernicus
Developed heliocentric idea and hypothesized that the earth orbits the sun in a uniform circular motion
Biggest challenge Galileo faced?
- being able to articulate novel scientific discoveries that conflict with political and religious doctrine
- getting funding for research
Father of modern science
Galileo Galilei developed observation. based science rather than authority-based science
When was the telescope invested?
1608 in Holland and design was improved by Galileo
Tycho Brahe
Surveyed the sky without a telescope, did not include difficult mathematical analysis of observations
Johannes Kepler
Assistant to Tycho Brahe, developed 3 basic laws of planetary motion
Kepler’s laws of planetary motion
Law 1: each planet moves around the sun in an ellipse
Law 2: planets sweep out equal areas in equal times
Law 3: P^3=a^2
Issac Newton’s Universal law of gravity
gravitational force = m1*m2/r^2
Acceleration of gravity
the acceleration of earth, moon, etc. does not depend on mass
Latitude
Measured in degrees with a zero point at the equator
Longitude
Measured in degrees or time
Declination and Right Ascension
correspond to longitude and latitude and given a position of an object in the sky instead of location on earth
Solar day vs. Sideral day
4 min difference between movement of sun and stars
Solar day
one rotation of earth based on sun
Sideral day
one rotation based with respect to stars
one day
based on the ratio of the earth
one month
based on the moon’s orbit around earth
one year
based on earth’s orbit around the sun
Heelstone
different stones that align with summer and winter sunrise and set which create shadows
summer solstice
earth’s tilt is facing the sun
winter solstice
earth’s tilt is away from the sun
Equinox
when daylight and night light are exactly 12 hours
Tidal Locking
the moon spins on its own axis one for each orbit around the earth so we always see the same side of the moon
when are ocean tides strongest?
full mood
when are ocean tides weakest
quarter moon
Light
can be a particle or a wave
wavelength
distance between two like points of a wave
frequency
a count of the number of waves passing through a point
speed of light
the physical speed when waves pass through a vacuum = frequency * wavelength
photon
particle of light
the energy of a photon
constant/h*speed of light/c divided by wavelength
blackbody radiation
red glow of radiating heat
The Doppler effect
speed of an object is related to the amount of shift in wavelength of light we receive from it
Why are telescopes needed?
earths atmosphere hold certain gases and dust that block certain forms of light
Refracting telescope
bending of path of light bean as it passes from one material to another
reflecting telescope
uses single lens
light gathering power of telescopes
based on the aperture (diameter) of the opening that collects light
resolving power of telescopes
based on the wavelength of light and the diameter of the telescope
magnifying power of telescopes
enlarge images
