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83 Cards in this Set
- Front
- Back
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What is our place in the universe? |
Earth, solar system, milky way, local group, local supercluster, universe |
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How many constellations exist? |
88 constelations |
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How far away is the nearest star from Earth? |
Several light years away |
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How far away is the nearest galaxy? |
A million light years |
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What is the size of the observable universe? |
13.7 billion light years |
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How many stars are there in the Milky Way? |
10^11 |
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How many galaxies in the universe? |
10^11 |
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What degree is the Earth's spin tilt angle? |
23.5 degrees (axis tilt) |
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What is the moon's orbit tilt angle? |
5 degrees |
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Another name for the Local Supercluster? |
Laniakea |
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What is a star? |
A glowing ball of gas that generates heat and light through nuclear fusion |
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What is a planet? |
Large piece of rock/gas that orbits a star |
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What is a moon? |
Object that orbits a planet |
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What is an asteroid? |
Rocky object that orbits a star |
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What is a comet? |
A small and icy object that orbits a star |
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Solar System |
A star and all the material that orbits it |
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What is a nebula? |
An interstellar cloud of gas and dust |
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What is a galaxy? |
An island of stars in space that orbit a common center |
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How quickly does light travel? |
300,000 km/s |
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What is a light-year? And how fast can it travel? |
The distance light can travel in one year (10 trillion km/ 6 trillion mi) |
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What is Hubble's Observation? |
All galaxies seem to be moving away from us
Velocity = Hubble Constant x Distance
AKA Homogeneous Expansion |
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How old is the universe? (Big Bang Theory) |
13.7 billion years old |
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How quickly does Earth rotate on its axis? |
1,000 km/hr |
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How quickly does Earth rotate around the sun? |
100,000 km/hr |
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What is a constellation? |
A region of the sky |
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What is the Celestial Sphere? |
Stars at different distances all appear to lie on the Celestial Sphere |
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What is the Milky Way? |
A band of light making a circle around the celestial sphere. It is our view into the plane of our galaxy. |
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What is the Local Sky? |
An object’s altitude (above horizon) and direction (along horizon) specifies its location in your local sky
Zenith: point directly overhead Horizon: all points 90 degrees from zenith Meridian: line passing through zenith and connecting N and S points on horizon |
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How do we measure the sky? |
Using angles
full circle: 360 degrees 1 degree = 60 arcminutes 1' = 60 arcseconds |
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What stars can we see? |
Stars rise in the east and set in the west. Stars of the North Celestial Pole are never set. Stars of the South Celestial Pole are never seen. |
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What is latitude VS longitude? |
Latitude: Horizontal (determines stars)
Longitude: Vertical |
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What are the four progressions of the seasons? |
summer solstice winter solstice spring equinox fall equinox
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What is an equinox? |
Night and day are equal lengths sun is over equator March 21 and September 23 |
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What is a solstice? |
The sun has traveled the furthest north or south Northmost (tropic of cancer) is summer, southmost (tropic of capricorn) is winter |
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What is a Lunar Phase? |
The moon's 27.3 day orbit around the Earth |
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What is the Sidereal Period? |
27.3 days, the time it takes the moon to travel around the Earth |
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What is the Synodic Period? |
29.5 days, the time between new moons |
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What is a New Moon? |
When the moon is closest to the sun during orbit. The moon is the darkest. |
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What is a Full Moon? |
Farthest from the sun. All white. |
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What is a Quarter Moon? |
Half lit. |
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What is the difference between waxing and waning? |
Waxing is the growing of the lit surface (rises at night) while waning is the shrinking of the lit surface (rises in the morning). |
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What is the order of the moon cycle? |
New Crescent First Quarter Gibbous Full Gibbous Last Quarter Crescent
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What defines a Lunar Eclipse? |
occur at full moon, behind the earth |
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What defines a Solar Eclipse? |
occurs at new moon, moon is in front of the earth |
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When do eclipses occur? |
1. Must be full moon for lunar eclipse, and new moon for a solar eclipse
2. Moon must be near one of the two points in orbit where it crosses the ecliptic plane |
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What is the Saros Cycle? |
A pattern where eclipses occur every 18 years and 11 1/3 days |
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What defines the Geocentric Model? |
Earth is at the center of the universe Objects move in perfect spheres/circles Plato supports Aristotle supports Ptolemy supports (Ptolemaic model) Stellar Parallax- closer stars change positions during the year |
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What is planet retrograde motion? |
When a planet stops moving, backs up, then moves forward again |
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What defines the Heliocentric Model? |
Sun centered model Used spheres/circle ellipses Copernicus supports Tycho Brahe supports Johannes Kepler supports |
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What are Kepler's three laws of planetary motion? |
1. The orbit of each planet around the Sun is an ellipse with the Sun at one focus
2.As a planet moves around its orbit, it sweeps out equal areas in equal times (faster when closer to the sun, slower when farther away)
3. More distant planets orbit the Sun at slower average speeds
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What are Galileo's discoveries? (Aristotelian views ) |
Earth could not be moving because objects in air would be left behind. Non-circular orbits are not “perfect” as heavens should be. If Earth were really orbiting Sun, we’d detect stellar parallax. |
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What is speed? |
The rate at which objects move |
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What is velocity? |
Speed and direction |
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What is acceleration? |
Any change in velocity |
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What is momentum? |
mass x velocity net force changes momentum
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What is angular momentum? |
Rotational momentum of a spinning or orbiting object |
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What are Newton's 3 Laws of Motion? |
1. An object moves at constant velocity unless a net force acts to change its speed or direction
2. Net Force = Mass × Acceleration
3. For every force from A to B, there is always an equal and opposite reaction force from B to A |
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What is the conservation of momentum? |
The total momentum of interacting objects cannot change unless an external force is acting on them Interacting objects exchange momentum through equal and opposite forces |
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What keeps planets rotating around the sun? |
The conservation of angular momentum angular momentum = mass x velocity x radius |
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What are the basic types of energy? |
kinetic (motion) radiative (light) stored or potential thermal (heat) |
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What is the conservation of energy? |
1. energy can neither be created nor destroyed
2. energy can transfer and change form between objects |
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What is the universal law of gravitation? |
1. every mass attracts every other mass
2. attraction is directly proportional to the product of their masses
3. attraction is inversely proportional to the square of the distance between their centers |
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How does gravity cause tides? |
Moon's gravity pulls harder on the nearest side of the earth |
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When do spring tides occur? |
New moon or full moon (strongest waves) |
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When do neap tides occur? |
Half moon (weakest waves) |
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What is tidal friction? |
Gradually slows the earth's rotation Moon gets farther from earth
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How do light and matter interact? |
Emission Absorption Transmission Reflection/Scattering
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What is reflection/scattering of light waves? |
Mirrors reflect light in a particular direction Movie screen scatters light in all directions |
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What is a wave? |
patterns that repeat themselves in space and time
carry energy without carrying matter |
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What is a wavelength? |
distance between two wave peaks |
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What is frequency? |
The number of times per second that a wave vibrates up and down |
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What is light? |
behaves as both a wave and an particle
a vibration of electric and magnetic fields
light interacts with charged particles through these electric and magnetic fields
photons |
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What is the electromagnetic spectrum? |
radio, infrared, visible (red, green, yellow, etc.), ultraviolet, x-ray, gamma ray |
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What is refraction? |
The bending of light when it passes from one substance to another |
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What are the two most important properties of a telescope? |
1. Light-collecting area
2. Angular resolution |
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What are the two basic designs of a telescope? |
1. Refracting telescope- focuses light with lenses
2. Reflecting telescope- focuses light with mirrors |
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What is imaging (with telescopes)? |
Taking pictures of the sky |
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What is Spectroscopy (with telescopes)? |
Breaking light into spectra
A spectrograph separates the different wavelengths of light before they hit the detector |
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What is timing (with telescopes)? |
Measuring how light output varies with time |
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Which forms of the electromagnetic spectrum are the easiest to see on Earth? |
Radio and visible waves |
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What is Interferometry? |
A technique for linking two or more telescopes so that they have the angular resolution of a single large one |
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What do x-ray telescopes use? |
grazing incidence |
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What is LIGO? |
Laser Interferometer Gravitational Wave Observatory |
