Phys 102 Astronomy Name ____________________ POSITIONS OF THE PLANETS PLANETARY POSITIONS WITH RESPECT TO THE SUN: Use appendix 11 in the Field Guide for the closest date to today to complete the following table: Object Planetary Longitude Elongation Atlas Chart # Constellation Sol () 178° 0° 27 Virgo Mercury (☿) 180° 2° E 27 Virgo Venus(♀) 220° 42° E 28/29 Libra Mars (♂) 52° 126° W 23/10 Aries Jupiter (♃) 202° 24° E 28 Virgo Saturn (♄) 127° 51° W 25/13 Cancer Luna (.) ELONGATION: Eastern Western Elongation Elongation South E South W E W The View From Earth PLANETARY POSITIONS IN EARTH’S SKY For TONIGHT (September 23, 2005), use Starry Night to determine times for the following planetary events and when you could actually SEE the planet (it has to be above the horizon and it has to be dark). RISING TIME TRANSIT TIME SETTING TIME TIMES VISIBLE1 Sol () 6:49:09 am 12:52:40 pm 6:55:54 pm Sunrise to sunset Mercury (☿) 7:11:31 am 1:11:03 pm 7:10:02 pm too close to sun to be visible Venus(♀) 10:42:19 am 3:33:28 pm 8:24:32 pm sunset to setting at 8:24 pm Mars (♂) 9:03:27 pm 4:12:21 AM 11:21:20 am rising at 9:03 pm to sunrise Jupiter (♃) 8:45:56 am 2:16:45 pm 7:47:32 pm sunset to setting at 7:47 pm Saturn (♄) 2:10:16 am 9:30:08 am 4:49:57 pm rising at 2:10 am to sunrise Uranus (♅) 6:02:54 pm 11:27:50 pm 4:52:46 am sunset to setting at 4:52 am Neptune (♆) 5:04:07 pm 9:59:04 pm 2:54:01 am sunset to setting at 2:54 am 1 Hours above the horizon during darkness. Planets in the Sky Solution092105.doc 10/14/2005 PLANETARY POSITIONS IN THE SOLAR SYSTEM A view of the solar system as seen FROM ABOVE THE NORTH ECLIPTIC POLE with the sun in the center is shown below. The line from the Earth ( ) to the sun () represents the planetary longitude of the sun. From the table on the first page, write the sun's planetary longitude on the solar system diagram. (Hold the page so that the words "Eastern Elongation" and "Western Elongation" are readable. ) For each of the five visible planets, 1) Center a protractor on the Earth, measure the elongation angle from the sun's longitude. 2) Use a ruler to determine where this crosses the orbit of the planet you're plotting, and mark the planet's position on its orbit. Special Note: Can you be certain where Mercury and Venus are in their orbits? How many positions for each planet are possible? What information will help you figure this out? Sol’s Planetary Longitude: __________ = Zero Elongation Eastern Elongation Western Elongation ♃ 24°E Mercury’s and Venus’ elongations are increasing so they’re ☿ on the far side of ♄ their orbits. 2°E 51°W ♀ ☉ 42°E ♂ 126°W Center protractor on Earth! Planets in the Sky Solution092105.doc 10/14/2005 PLANETARY POSITIONS IN THE SKY The digram below shows an observer looking south at sunset. From the planetary longitude of the sun and planets on top of the first page, show where the planets will be in the observer’s sky (some may be below the horizon). Discuss how these positions correspond to the times the planets will be visible to this observer that you listed on the bottom of the first page. Observer’s meridian ♃ 24°E Come look for the planets ♀ 42°E with me! ☿2°E E W Sun setting on observer western horizon looking ♄ south ♂ ♄ 51°W 126°W This diagram shows that Mercury, Venus, and Jupiter should be visible after sunset until they each set. Mercury, however, is too close to the sun to see since it will set long before the sky is dark enough to see it. Mars and Saturn will rise during the night and be lost from view when the sun rises in the morning. .