As we return to the classroom on Friday to take the quiz, we won't fly near any mythological figures today. We'll start seeing them again on Monday. THE SOUTHWORTH PLANETARIUM 207-780-4249 www.usm.maine.edu/planet <http://www.google.com/url?q=http%3A%2F%2Fwww.usm.maine.edu%2Fplanet&sa=D&sntz=1&usg=AFQjCNHulkHuLP13bOG2PkNrPazsGWFs2A> 70 Falmouth Street Portland, Maine 04103 43.6667° N 70.2667° W Altitude: 10 feet below sea level Founded January 1970 Julian Date: 245943.16 2019-2020: CXIX THE DAILY ASTRONOMER Friday, April 3, 2020 Remote Planetarium 5: Week I Quiz We've concluded the first week of the Remote Planetarium On-line classes. We're hoping you're enjoying these articles and that they make sense. Today we offer a quiz pertaining to some of the topics we introduced in week one. Yes, we will offer a final quiz when the classes end. Of course, as we will continue to offer the Remote Planetarium DA's until the end of the lockdown (and perhaps for a bit after), we don't know when the classes will end. Thank you for participating. Good luck with the quiz! 1. Which one of the following statements about the Celestial Equator isn't true? a. It extends from due east to due west b. Its position in the sky depends on the observer's latitude c. It does not intersect the meridian d. It passes directly overhead along the equator 2. Let's say you're observing the sky at 50 degrees north latitude. Which of the following statements is/are true? a. The Celestial Equator attains its greatest height above the due south point. b. The Celestial Equator's greatest angle would be 40 degrees. c. The Celestial Equator's greatest angle would be 50 degrees d. The Sun can never be higher than 63.5 degrees above the southern horizon. 3. Mintaka, the western most of the three stars forming Orion's belt is positioned very close to the Celestial Equator. So, Mintaka's declination would be __________ a. almost 0 degrees b. almost 23.5 degrees c. almost 90 degrees d. none of the above 4. What is the Sun's declination on the June solstice? a. 0 degrees b. 23.5 degrees c. 90 degrees d -23.5 degrees 5. What is Earth's "tilt angle," otherwise known as its obliquity? a. It isn't tilted at all b. 14 degrees c. 23.5 degrees d. 47 degrees 6. What is the "Zodiac?" a. the collection of animal constellations surrounding Orion b. the thirteen constellations through which the Sun appears to move throughout the year c. the constellations that never set at our latitude d. none of the above 7. Which of the following constellations are part of the Zodiac? a. Orion the Hunter b. Virgo the Maiden c. Taurus the Bull d. Pegasus the Winged Horse e. Leo the Lion f. Gemini the Twins g. Perseus the Warrior 8. The Sun appears in which constellation on the December Solstice? a. Pisces the Fish b. Taurus the Bull c. Virgo the Maiden d. Sagittarius the Archer 9. When the moon is between the Sun and Earth, what is its phase? a. new b. first quarter c. full d. last quarter 10. If the moon rises at sunset and sets at sunrise, what is its phase? a. new b. first quarter c. full d. last quarter 11. If the moon is 80% illuminated and rises 2.5 hours after sunset, what is its phase? a. waxing crescent b. waxing gibbous c. waning gibbous d. waning crescent 12. Which of the following statements about the moon is/are correct? a. one can only observe it around the zodiac region b. its orbital inclination relative to the ecliptic plane is about 5 degrees c. it is always half illuminated d. none of the above statements are true ANSWERS 1. c. It does not intersect the meridian The Celestial Equator extends from due east to due west. One can envision it as being like a ring around Earth's equator visible from every location. For northern hemisphere observers, it attains its greatest angle above due south. The meridian, which extends between due north and due south intersects the Celestial Equator at its highest point. 2. a, b, and d are true. a. For northern hemisphere observers, the Celestial Equator attains its greatest height above the due south point. b. At 50 degrees latitude, the Celestial Equator's greatest angle equals 90 - 50 = 40 degrees c. At 50 degrees latitude, the Celestial Equator's greatest angle equals 90 - 50 = 40 degrees d. The Sun's highest angle in the sky would be equal to 23.5 degrees + Celestial Equator's greatest angle. For an observer at 50 degrees latitude, the Sun's highest angle equals 40 + 23.5 = 63.5 degrees 3. a. almost 0 degrees "Declination" is the celestial equivalent to latitude. An object on the Celestial Equator has a declination of 0 degrees. An object at the north celestial pole has a declination of 90 degrees. An object at the south celestial pole has a declination of -90 degrees. In the star chart below, we can see Mintaka (name not included) just below the celestial equator. Sirius, the night sky's brightest star, is more than 16 degrees 42 minutes south of the Celestial Equator, so its declination equals -16 degrees 42' [image: RA-Dec-eq-region-with-coordinates.jpg] 4. b. 23.5 degrees Declination measures a celestial object's angle relative to the Celestial equator. On the June solstice, the Sun reaches its highest altitude of 23.5 degrees north of the Celestial Equator and so its declination measures 23.5 degrees. On the December solstice, the Sun's declination measures -23.5 degrees. 5. c. 23.5 degrees Earth is tilted on its axis by 23.5 degrees relative to vertical. As Earth revolves around the Sun, the north pole's orientation relative to it changes . On the June solstice, the north pole is aligned toward the Sun. On the December solstice, the north pole is directed away from the Sun. Throughout the year, the orientation gradually changes as it vacillates between these two extremes. See image below: [image: SS2776969.jpg] 6. b. the thirteen constellations through which the Sun appears to move throughout the year. These constellations are located along the ecliptic. 7. b. Virgo the Maiden c. Taurus the Bull e. Leo the Lion f. Gemini the Twins The list of Zodiac constellations: Pisces the Fish, Aries the Ram, Taurus the Bull, Gemini the Twins, Cancer the Crab, Leo the Lion, Virgo the Maiden, Libra the Scales, Scorpius the Scorpion, Ophiuchus the Serpent Charmer, Sagittarius the Archer, Capricornus the Seagoat, Aquarius the Water Bearer 8. d. Sagittarius the Archer The Sun appears to occupy Pisces the Fish region on the first day of spring; Taurus the Bull on the first day of summer, Virgo the Maiden on the first day of autumn and Sagittarius the Archer on the first day of winter. [image: 800px-Taurus_IAU.svg.png] The sky is divided into 88 rectilinear regions, each of which is centered on a different constellation. The ecliptic passes through thirteen of these regions. As we see in the above image, when the Sun travels "through" Taurus, it is not always directly on the stars comprising it. The Sun is said to "enter" Taurus when it moves across the demarcation separating the Taurus region from that surrounding Aries the Ram. 9. a. Technically known as "conjunction," the moon is new when it passes between the Sun and Earth. 10. c. full We recall our rough rules of thumb NEW MOON: Rises and sets with the Sun FIRST QUARTER MOON: Rises around noontime, sets around midnight FULL MOON: Rises at sunset; sets at sunrise LAST QUARTER: Rises around midnight, sets around noon 11. c. waning gibbous Waning gibbous is the phase that follows the full moon, but precedes the last quarter moon. Full moon rises around sunset and the last quarter moon rises around midnight. Waning gibbous is also between 50% - 100% illumination, not inclusive. So, if the moon is 80% illuminated, it is gibbous. If it rises after sunset but before midnight, it is waning gibbous. 12. a. one can only observe it around the zodiac region b. its orbital inclination relative to the ecliptic plane is about 5 degrees c. it is always half illuminated The first two statements fit nicely together. Because the moon is inclined by slightly more than five degrees relative to the ecliptic, Earth's orbital plane, one will observe it only within the zodiac region centered on the ecliptic. Also, the moon is always half illuminated by the Sun. We see different phases because of its changing orientation relative to the Earth-Sun line. To subscribe or unsubscribe from the Daily Astronomer: https://lists.maine.edu/cgi-bin/wa?SUBED1=DAILY-ASTRONOMER&A=1