qz2solsyskey-keyf20online

Astronomy B3 Solar System class — Strobel F20 Quiz#2 KEY Canvas shuffles the order of answer options within each question. Each student has a different looking quiz—same questions asked with same possible options but shuffled. The correct option letters for your version of the quiz is now on the online quiz. Use the key below to get the explanation of why it is the correct option. 1. The Moon is lit up on the left side so it is a waning gibbous (remember “d –wane”). A waning gibbous sets a little after the Sun rises—up to a few hours after sunrise. See the table in section 3.7.1 in the textbook (on p. 61 of the 2019/2020 edition) and #15 of Lunar Phases worksheet. The question asked when the waning gibbous Moon was near the western horizon. The figure on the next page shows the Waning Gibbous phase position and observer’s position if the Moon is on a flat western horizon. A little before then in time (closer to sunrise), the Moon would off in the western sky. The Moon-Planets lecture slides had an example worked-out problem with the same phase but asked when the waning gibbous Moon was highest in the sky due south. 2. The first figure of section 3.7.1 of “Astronomy Notes” and p. 119 of the Student Guide (and Lunar Phases worksheet) show that the phase shown in the quiz question is a third quarter phase. A third quarter phase has the daylit half side facing left. The Moon orbits counter-clockwise around the Earth. In the Earth-Moon orbit pictures, remember that the day side of the Moon has to face the Sun (the Sun is what makes the daylight/moonlight!). Options (c) and (d) have the night side facing the Sun! 3. Solar eclipses happen only twice a year because the Moon's orbit plane is tilted with respect to the ecliptic (the Earth's orbit plane). See the Moon orbit plane figures in section 3.7.1 of the Astronomy Notes textbook (pages 61-62 of the 2019/2020 edition) Usually, the Moon is not in the ecliptic plane when it is at new or full phase so eclipses do not happen. Straight from concept 23 of the exam review sheet . 4. Venus and Mercury are always near the Sun in the sky. The Sun sets in the west and rises in the east, so choose the option Venus & Mercury in the same direction as the Sun at the given time of day. Three of the options have Venus on the opposite side of the sky from the Sun. One of those options also has the quarter moon in the wrong position at midnight (only the full moon is high up at midnight). The option with the full moon has the full moon at the wrong position at sunset. The full moon is just rising at sunset. See sections 3.7.1 and 3.8 of “Astronomy Notes”, the Mapping the Solar System activity in section 3.2 of the Student Guide and concepts 19–21, 24, 25 of the exam #1 review sheet . 5. Neptune will set at 9 PM. At sunset, the person would be pointed straight down toward the bottom of the page and the horizon line would be horizontal---straight left-right in the figure.. The Sun would be on his right horizon (west) and Neptune would be in the southwest. A few hours after sunset, the horizon has rotated counter-clockwise, so Neptune would be about to set (see the figure below). Choose the only option that is after sunset in the evening! See the Mapping the Solar System activity (section 3.2 of the Student Guide) and the figure below. To Sun (+ noon direction) dashed horizon line for late morning East midnight sunset sunrise observer’s meridian direction after sunrise The observer’s time is after sunrise West

Astronomy B3 Solar System class — Strobel F20 6. Position B. Based on the discussion in the Lunar Phases worksheet and the Mapping Solar System Help pages 122-125 of the Student Guide, someone at the leftmost edge of the Earth circle will be experiencing sunset. At 8 PM, the observer’s horizon is as shown in the figure below. Anything to the LEFT of that horizon line would be above the person's horizon and visible. This cancels out options (d), (e), (f) right away. (figures below and next page ! ) Earth Neptune Sun East horizon West horizon Neptune setting Toward meridian (south) To Sun Noon 6 PM (sunset) Midnight 6 AM (sunrise) West horizon East horizon 9 PM Observer facing South Toward meridian (south) Sun Horizon line for 8 PM Horizon line for 8 PM Position for quarter phase (half full). Earth-planet-Sun angle = 90º Gibbous (most of day side facing Earth) Everything to the right of the horizon line canNOT be seen by 8 PM observer Direction observer is facing at 8 PM To Sun Noon 6 PM (sunset) Midnight 6 AM (sunrise) East horizon West horizon 8PM Observer facing South