Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
80 Cards in this Set
- Front
- Back
|
Order of magnitude
|
focuses on the exponent, not the actual number
|
|
|
How far apart is the Earth and the Sun?
|
150 million km, or 1 AU
|
|
|
How far apart are individual galaxies?
|
300,000 light years apart
|
|
|
What is a pulsar?
|
A blinking, pulsing light at the center of a recently exploded supernova.
|
|
|
Where are stars formed?
|
stellar nurseries
|
|
|
What is Earth's diameter?
|
13,000 km
|
|
|
Define planet.
|
a small, spherical, nonluminous orbital body
|
|
|
Define star.
|
A self-luminous ball of hot gas generating its own energy.
|
|
|
What is an asterism?
|
a less formally defined grouping of stars
|
|
|
What is the star nearest to the sun? What is the brightest star in our sky?
|
Alpha Centauri; Sirius
|
|
|
What is flux?
|
the measure of the light energy from a star that hits one square meter in one second
|
|
|
What is precession?
|
the top-like motion of Earth that results in the appearance of celestial poles moving across the sky
|
|
|
What information can astronomers receive from examining a star's light? (6)
|
energy output, surface temp, radius, chemical composition, velocity relative to earth, rotation period
|
|
|
What is the speed of light?
|
300 million m/s
|
|
|
What is a light year?
|
the distance light can travel in a year-- 9.46 trillion km
|
|
|
Name 5 that light is wave-like.
|
it has an electromagnetic field, it defracts, it interferes, it reflects, and it refracts
|
|
|
Name 4 ways that light is particle-like.
|
It is made up of photons, it has blackbody radiation, it displays a photoelectric effect, and Compton scattering.
|
|
|
What is a spectrum?
|
a plot of brightness versus wavelength.
|
|
|
What is a blackbody object?
|
An idealized object that doesn't reflect any light, but only radiates it.
|
|
|
Take note of what is amplitude and what is wavelength.
|
okay.
|
|
|
What is blackbody radiation?
|
an electromagnetic spectrum characteristic of an object's temperature
|
|
|
Radio>>Microwave>>Infrared>>Visible>>Ultraviolet>>X-ray>>Gamma ray. Wavelength (increases or decreases) and frequency (increases or decreases)
|
decreases; increases
|
|
|
What are the two laws of blackbody radiation?
|
-the hotter an object, the more energy it emits.
-the peak of the blackbody spectrum decreases (to the left) with increasing temperature. |
|
|
Where is most of the mass of an atom contained?
|
in its nucleus
|
|
|
Explain absorption spectrum/lines.
|
Electrons are energized (kicked into a higher orbital level) when it absorbs a photon with just the right amount of energy. When light passes through a cool, low-density gas that absorbs a photon at a unique frequency, the light re-emitted shows up as dark in the spectrum. These lines are absorption lines.
|
|
|
What are Kirchoff's laws of radiation? 3
|
- a solid, liquid, or dense gas excited to emit light will radiate at all wavelengths and produce a continuous spectrum.
- a low-density gas emitting light will do so at specific wavelengths, producing an emission spectrum. - a cool, low-density gas emits light, the result will be an absorption spectrum. |
|
|
Balmer lines of hydrogen:
|
Emission or absorption lines that occur from transitions between the second state and higher states of the hydrogen atom.
|
|
|
Doppler effect:
|
sound gets louder when moving toward you and quieter when moving away from you (same thing with the intensity of light; it shifts from red to blue)
|
|
|
What do optical telescopes do?
|
they focus light to gather more than our eyes can see
|
|
|
What are two types of optical telescopes?
|
Refracting and reflecting
|
|
|
What do refracting telescopes use to focus light?
|
a lens
|
|
|
What is a major disadvantage of a refracting telescope?
|
Chromatic aberration (different wavelengths are focused at different focal lengths)
|
|
|
What do reflecting telescopes use to focus light?
|
a mirror
|
|
|
What four things do telescopes need to work? Describe these things.
|
light-gathering power (dependent on surface area), resolving power (minimum angular distance between objects), seeing (clarity), magnifying power (makes image bigger)
|
|
|
How big do radio waves have to be to penetrate atmosphere and be observed from the ground?
|
1 cm - 1 meter
|
|
|
What is the best location for a telescope?
|
Far away from light pollution and high up to minimize atmospheric blurring
|
|
|
What two principles did early astronomers base their models on that were incorrect?
|
Geocentric universe and the "perfect heavens"
|
|
|
Thales:
|
Everything in the universe is made of water.
|
|
|
Anaximander:
|
Earth in the center of the universe was cylindrical, surrounded by a rotating spherical shell of fire with perforations (stars) and two wheels of fire with holes that periodically closed (moon and sun)
|
|
|
Pythagoras:
|
The planets are supported by spheres that rotate around the Earth.
|
|
|
Plato:
|
the heavens are perfect
|
|
|
Aristotle:
|
the sub-lunar realm is changing, imperfect, and made up of four classical elements that have its natural tendency and place. the super lunar realm is perfect and unchanging.
|
|
|
Why didn't ancient astronomers believe the earth moved?
|
They saw no parallax (apparent motion of an object due to the motion of the observer) and observed a retrograde motion of planets.
|
|
|
How did Ptolemy attempt to explain retrograde motion of planets?
|
with epicycles
|
|
|
Who proposed a heliocentric model for the first time and in what book?
|
Copernicus; De Revolutionibus
|
|
|
Other than the heliocentric model, what else did Copernicus propose? (4)
|
- Earth is a planet.
- Earth has 3 kinds of motions: daily, annual, and axis tilting/wobbling. - He explained retrograde motion of planets. -Proposed that the distance between the Earth and the sun is relatively small. |
|
|
What did Brahe and Kepler figure out?
|
the motion of mars (flattened ellipse
|
|
|
What are Kepler's three laws of planetary motion?
|
- The orbit of every planet is an ellipse. The semi-major axis is half of the longest diameter of an ellipse.
- Planets move quicker when closer to the sun. - P^2 = a^3 (Planet's orbit period in years and semi major Axis in AU) |
|
|
What are 5 of Galileo's discoveries?
|
1. moons of Jupiter
2. rings of saturn 3. moon's texture & structure 4. sun spots 5. places of venus |
|
|
What are Newton's 3 laws of motion?
|
1. An object in motion stays in motion unless a force is acted upon it.
2. The acceleration of a body is inversely proportional to its mass, directly proportional to the net force, and in the same direction as the net force. - To every action, there is an equal and opposite reaction. |
|
|
What is acceleration?
|
the change of a body's velocity with time
|
|
|
What are three different cases of acceleration?
|
-Increasing speed
- Decreasing speed - Change in direction |
|
|
The acceleration of gravity is ______________ on the mass of the falling object.
|
independent
|
|
|
What is Newton's Universal Law of Gravity?
|
Any two bodies are attracting each other through gravitation, with a force proportional to the product of their masses and inversely proportional to the square of their distance.
|
|
|
What is a geosynchronous orbit?
|
An orbit in which an object orbits Earth at exactly the same rate that Earth rotates
|
|
|
Name four pieces of evidence for the Big Bang.
|
- The sky is not blindingly bright
- Galaxies are moving apart - Background radiation is present in all directions in the universe - Hydrogen to Helium ratio is consistent with what is predicted |
|
|
What is Olber's paradox? What is the solution to Olber's paradox?
|
If the universe is infinitely old, then every line of sight should end at the surface of a star.
- The universe is finitely old. |
|
|
What is Hubble's law?
|
distant galaxies are flying away from us with a speed proportional to distance (father away, faster they go)
|
|
|
How do we know how far away stars and galaxies are? 5
|
parallax, cepheid variable stars, diameter of a globular cluster, characteristic brightness of supernovae from white drawfs, size distribution of galaxies in clusters of galaxies
|
|
|
What is a parsec?
|
3.26 light years; distance between me and another object that makes an angle of one arc second and the base line is 1 AU
|
|
|
What are Cepheid variable stars?
|
They're massive and their variability period is correlated with its luminosity.
|
|
|
How old is the universe?
|
about 14 billion years old
|
|
|
What is an anti-particle for an electron?
|
Positron
|
|
|
What happens when positron and electron collide?
|
they create pure energy and gamma-ray photons.
|
|
|
What happens when photon and photon collide?
|
they create electron and positron again
|
|
|
What is the recombination period?
|
When the universe cooled, protons and neutrons fused together to create helium nuclei and protons electrons fused to form hydrogen atoms.
|
|
|
What followed the recombination era?
|
the dark age
|
|
|
How old was the universe when the first stars formed?
|
less than 1 billion years old
|
|
|
In what three ways do we classify stars?
|
Luminosity, temperature, and size
|
|
|
How is a star's brightness related to its size?
|
Directly proportional
|
|
|
Know the hertzsprung-russel diagram
|
okay.
|
|
|
Speed of light equation:
|
c= fλ
c-- speed of light in meters/s λ--wavelength in meters f--frequency in cycles/s |
|
|
Energy related to frequency equation:
|
E=hf
E--energy of photon in Joules h--Planck's constant f--frequency in cycles/s |
|
|
Wien's law describing wavelength of blackbody radiation at its maximum intensity:
|
λmax = 2.9*10^6
--------------- T |
|
|
Doppler shift d escribing how the wavelength of light changes if its light is observed from an object moving toward or away from a light source at a radial velocity.
|
Δλ = v radial
------ ----------- λ0 c |
|
|
Kepler's third law:
|
a^3 = P^2
|
|
|
Newton's second law:
|
F = ma
|
|
|
Newton's law of gravitation
|
F = -GMm
----------- r^2 |
|
|
Newton's laws of motion and gravitation
|
4π^2a^3 = GMP^2
|
|
|
Luminosity, blackbody radiation, and radius equation:
|
L = 4πR^2δT^4
|
