Astronomy Second Test Flashcards
9a Reasons for seasons
1) Sun’s light hits earth at a more grazing angle heating earth up less
2) The shorter day length in winter means that the ground spends less time being heated up
9b Include an Earth diagram, showing the Tropics, Arctic and Antarctic circles with their latitudes, plus incoming sunlight and the terminator for late June.
Draw earth with tropics at 23.5° and arctics at 66.5°. Lines straight across not curved. terminator for late june- left to right going up. sunlight coming in down L to R. CHECK ARCTIC CIRCLE LATS
11a) Describe the astronomical coordinate system, including the units used.
The astronomical coordinate system is essentially Earth’s coordinate system projected out onto the celestial sphere. Declination (dec or delta), measured in degrees, is a measure of how far north something is from the celestial equator (similar to latitude). Right ascension (RA or alpha), measured in hours/minutes/seconds, is how far east something is from the vernal equinox (similar to longitude)
11b) Draw a diagram of the ecliptic path that illustrates how we define the origin (0, 0 point) of the system, labeling the positions and dates of the equinoxes and solstices.
Just draw a box with 0,0 at the middle with the vernal equinox, various dates with the autumnal equinox on the sides. Have arrows pointing for RA and dec going up and down.
12- a) For us at 45 degrees north latitude, what is the angle between the sun and the zenith at midday on the summer solstice, the winter solstice and the fall equinox?
Cel eq and zen angle is 45°. cel eq and jun 21 light angle is 23.5°. Subtract 45-23.5° to get angle. on winter solstice 68.5°, equinox 45°.
12b) b) Draw a diagram of the Earth that illustrates all 3.
Draw earth, guy on limb about halfway up. Draw a line parallel to equator at his pos, then lat angle from real eq, then sun angles from his cel eq. label angles etc.
13-a) Explain why there is a difference between synodic and sidereal months, which is longer, and by about how much. Include a diagram.
The synodic month is how long it takes for a phase of the moon as seen from earth to repeat itself. The sidereal month is how long between occultations of a particular star by the moon. The syndodic month is longer by two days because the earth’s revolution around the sun means that it takes a bit longer for the moon to replicate the same phase as it does to occult a distant star. Diagram- just practice it.
13b) If you see the moon setting 6 hours after the sun, roughly how many weeks is it until the next full moon? Draw another diagram showing where the sun, earth and moon would be in its orbit at that time, and mark what direction is eastward.
If it set at same time as sun it is on same side as sun and thus a new moon- quarter moon is 6hrs off, on side, while a full moon is 24 hours off, on other side. If it sets 6hrs after sun it is behind sun, thus the
14- a) Use 2 diagrams of sun, earth and moon to show: 1- the three types of lunar eclipses; 2- the three types of solar eclipses. Label each type of eclipse, and describe its appearance.
Show total, partial, penumbral lunar. Then: total, partial, and annular solar. HOW TO SHOW DIFFERENT SOLARS? Esp. annular.
Lunar appearances: total - dark and red
partial-partially dark and red
penumbral - no change in appearance
Solar appearances:
total - sun blocked, only corona visible
partial - sun partially blocked from side
annular- moon concentric inside of sun
b) Draw a diagram showing the forces that cause the tides on Earth.
Earth, moon, tidal arrows. ASK: Do I have to “derive” the arrows or not?
15- a) Describe what it would be like to stand on the dayside of the moon. Include a description of the ground, approximate temperature compared to earth, gravity, appearance of the sky and how you see the earth move in the sky above you.
Standing on the dayside of the moon would put you in 2-4” of lunar talc dust. The ground is bleak and looks like black and white. The temperature is much hotter than earth, around 240°. You feel light, as the moon’s gravity is 1/6th that of earth’s. APPEARANCE OF SKY ??? The earth does not move its apparent position.
15b) At midday on the moon, what phases are possible for the Earth as you would see it, and draw a diagram to illustrate this answer?
The possible phases of earth are the same as those of the moon. The phases of earth would be opposite the chart from the phases of the moon seen from earth.
16- a) Describe the Apollo Lunar Landing Modules (LEMs). Include their overall appearance, how they slowed their descent for landing, the procedure for launching the rovers, how many astronauts were aboard each one, how they got to the surface and how many successful landings there were.
The LEM like a pod on spider legs. Slowed down for landing with retrorockets. Two astronauts in each. Rover was in bay on pod, wheels lowered first than rover layed onto it. They got to the surface after being launched from a lunar orbiter with an additional crewmember above it. There were X successful landings.
17-a) Draw a diagram of the non-ionized hydrogen atom, showing what’s in the nucleus, 3 electron orbits (not to scale), and indicating how light is absorbed and emitted by the atom.
Three electron orbits does NOT mean three electrons. Question: do orbits have to be lobes or can we do the bohr model? One electron, one proton, no neutrons. How light is absorbed and emitted: look for the diagram that shows jumping and use that
17b) Explain why only specific colors of light are absorbed by a cloud of hydrogen gas.
Atoms only absorb light whose energy is equal to the energy it takes for one of its atoms to jump to a different orbit. Thus, when light passes through a cloud of hydrogen the atoms that make up the cloud only absorb certain wavelengths of it.
