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;
41 Cards in this Set
- Front
- Back
|
What is a perigee? |
When the moon is closest to Earth. |
|
|
What is an apogee? |
When the moon is furthest from the Earth. |
|
|
What is a sidereal month? |
A complete rotation of the Earth-Moon system (27.33 days). Sidereal means star. |
|
|
What is a synodic month? |
Full moon to full moon (29.5 days). |
|
|
What is meant by ecliptic? |
The path that the Moon, Sun, and planets appear to follow across the sky. |
|
|
What is meant by libration? |
This refers to the Moon’s “wobble”.
|
|
|
What is perihelion? |
When we are closest to the Sun (Dec. 21). |
|
|
What is aphelion? |
When we are farthest from the Sun. |
|
|
What is a solar eclipse? |
This is when the Moon is between the Sun and the Earth. Because the Moon is much smaller than the Earth, its shadow only covers a portion of the Earth. |
|
|
What is the photosphere? |
This begins what is arbitrarily called the atmosphere of the Sun. This is the bright disk that we see. They have the characteristic sunspots. It has a temperature of 6000 degrees. |
|
|
What is a sunspot? |
Darker regions on the photosphere. They are patches of cooler gases caused by the rising and falling of the gases. They follow regular time cycles of 22 Earth years. |
|
|
Core of the sun |
This is where the nuclear fusion of hydrogen (H) into (He) is thought to occur producing the energy that drives the sun. |
|
|
Radiative Zone |
Region is so compact that material cannot diffuse outward. |
|
|
Convection Zone |
Rising of warm gases as they are less dens than the cooler gases. As the gases closer to the radiative zone hat up, they diffuse to the outer “cooler” portion of the convection zone. |
|
|
Photosphere |
This begins what is arbitrarily called the atmosphere of the Sun. This is the bright disk that we see. They have the characteristic sunspots. It has a temperature of 6000 degrees C. |
|
|
What are sunspots? |
Darker regions on the photosphere. They are patches of cooler gases caused by the rising and falling of the gases. They follow regular time cycles of 22 Earth years. |
|
|
What is the reversing layer? |
Outside the photosphere. There the gases are cooler and less thick. They can absorb certain wavelengths of light coming from the photosphere. This produces a dark line or absorption spectrum. This is how helium was discovered on the sun- a pattern of spectral lines was detected that we had not seen before. |
|
|
What is the chromosphere? |
Much hotter layer than the reversing layer. It is a much thinner layer but has a higher temperature because of the greater velocity of its particles. It has characteristic spicules, prominences, and chromospheric flares. |
|
|
What is a spicule? |
Spicules: cooler gases that extend to the outer corona. They last for about 5 to 15 minutes. They may be a means of transferring energy from the outer-lying convection zone to the corona. Kind of like spikes. |
|
|
What is a prominence? |
Prominences: These are huge rose-colored flames of burning hydrogen gas. They average 20,000miles high and 200,000,000 miles across at the base. They rise upward at200-300 miles per second. Biggest one seen 1937 |
|
|
Describe a chromospheric flare. |
These reach height of 10k miles. Emit intense radiation as X-rays, ultraviolet, and radio waves that travel away from the sun. They effect radio communications and the magnetic field of the Earth. |
|
|
What is the corona? |
This is the outer atmosphere of the sun. only seen during a solar eclipse. 1 mil.degrees C. |
|
|
What is Hydrostatic Equilibrium? |
Pressure from the interior of the sun pushes outward an gravity pulls inward. If the outward pressure should sufficiently diminish, the star could collapse into a white dwarf, neutron star or black hole. |
|
|
Describe the Emission Spectrum. |
Hot objects give off light depending upon the energy levels of its electrons. |
|
|
What is the Doppler Effect? |
When a sound emitting object approaches, the pitch (frequency and loudness) of the sound increases. When the sound emitting object moves away, the pitch decreases. |
|
|
Describe the Red Shift. |
When an object (like a star) is moving away from the observer at an appreciable velocity (10% speed of light), the frequency of light from the star decreases and the emission spectrum is shifted slightly to the red (lower energy) side.
|
|
|
Describe a Cosmological Redshift. |
Caused by an expansion of space. The wavelength of light increases as it traverses the expanding universe between its point of emission and its point of detection by the same amount that space has expanded during the crossing time.
|
|
|
Describe a Gravitational Redshift. |
A shift in the frequency of a photon to lower energy as it climbs out of a gravitational field. |
|
|
What are the 3 varieties of binary stars? |
Binary stars can be either detached binaries (gas between them), semi-detached binaries (some gas between them), or contact binaries (no gas between them). |
|
|
Describe a Variable Star: |
Where the magnitude of a star varies with a regular period. Some are eclipsing binaries and some are novas. |
|
|
What is apparent magnitude? |
Magnitude (brightness) of a star as seen by an observer· Lower numbers indicate greater brightness |
|
|
What is AbsoluteMagnitude? |
Besides the actual brightness of a star, its apparent magnitude is also determined by its distance from us. · Absolute magnitude is the magnitude of stars if they were all 10 parsecs away. This cancels out the effect of the distance of the star.
|
|
|
What is an H-R Diagram? |
· Hertzsprung-Russel diagrams are graphs plotting the temperature of stars with their absolute magnitude (or luminosity) |
|
|
Rotating neutron stars are called: |
Pulsars (give off precise radio signals; massive- exert a gravitational pull on stuff around them). |
|
|
What is a black hole? |
Formed by the collapse of a massive remnant after a supernova. Theyhave a singularity in the middle and an event horizon. |
|
|
What is a Protostar?
|
A protostaris a region in a nebula where the gases are concentrated enough to becollapsing due to gravitational forces. (ex: Great Nebula of Orion). |
|
|
Describe Star Death |
Wherea star explodes because its source of energy pushing outward decreases and itsgravity causes it to collapse. The great energy generated by the collapsing ofthe star causes it to explode. EX: Supernova |
|
|
Decay of the Speed of Light theory: |
Sin caused the speed of light to slow down so that it would have been much faster in the past. -Would make the universe appear much older than it is. -Variations in the measurements of the speed of light have been within experimental error, so the results are inconclusive. |
|
|
Starlight Hypothesis Theory |
Most popular view amongst creationist scientists -Universe began as a mass of water (Spirit of God hovered over the face of the deep). -Most of it underwent a tremendous white hole (expanded instead of compressing) and became the universe. The core became the Earth which remained stationary. |
|
|
Curved Space Theory |
This view states that the large scale of the Universe (with large gravitational fields of clusters of massive galaxies) operates under a different set of laws of physics just as subatomic particles below the level of the atom. -According to this theory, light could travel from one end of the Universe to the other in 7 years. -the whole issue of starlight could become a mute point. |
|
|
ChandrosekarLimit |
-If the mass of the collapsing remnant is 1.4 solar masses or greater, it will collapse into a neutron star. -If the collapsing remnant has a mass of 2 to 3 solar masses, it will collapse into a black hole. |
