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Stargazing 101

Stargazing 101. “The Moon and the Sun” (Chapter 8) “Solar and Lunar Eclipses” (Chapter 9) October 6, 2009. Homework: Phases of the Moon. “How is it going so far?” Not due until the last class, November 3, 2009, but we just completed one series of phases New Moon to Full Moon.

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Stargazing 101

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  1. Stargazing 101 “The Moon and the Sun” (Chapter 8) “Solar and Lunar Eclipses”(Chapter 9) October 6, 2009

  2. Homework: Phases of the Moon • “How is it going so far?” • Not due until the last class, November 3, 2009, but we just completed one series of phases New Moon to Full Moon.

  3. Homework: Phases of the Moon

  4. Homework: Phases of the Moon

  5. Homework: Phases of the Moon • A practical assignment to give you a sense of: • How the Moon moves across the sky in its monthly orbit around the Earth • How its varying brightness can effect stargazing • It causes “light pollution,” making it difficult to see dim stars in its brighter phases. • What times in the lunar month are the best time to see the stars.

  6. The Moon “The Moon is not smooth, and uniform, but is uneven, rough and full of cavities.” Galileo Galilei, 1609

  7. A Moon Joke • “Have you heard about the new restaurant on the Moon?” • “Great food, but no atmosphere!”

  8. The Moon • Galileo is the first person, as far as we know, who looked at the Moon with magnification – a telescope • Binoculars – can get very sharp and clear views • Telescopes– can see a lot of detail • Detail up to about ½ mile with large telescopes

  9. Moon - Formation • The Moon is believed to have been formed after a large object (even Mars size) hit the Earth, ejecting debris into space • The debris was held by the Earth’s gravity • Eventually, this coalesced into the Moon Explorations: An Introduction to Astronomy, Thomas T. Arny, p. 195

  10. Moon - Formation • The interior was molten • A crust formed as the Moon cooled, but before it became thick • Some larger impacts formed large basins, which filled in with lava • The Seas or Maria Explorations: An Introduction to Astronomy, Thomas T. Arny, p. 195

  11. Moon – Formation of Seas Explorations: An Introduction to Astronomy, Thomas T. Arny, p. 196

  12. The Moon • What can we see? • Craters – caused by the impact of solid bodies on its surface • Named after prominent philosophers and scientists • Size and depth of crater depends upon the mass and velocity of the impacting object • Plains – are also believed to be caused by impact of solid bodies • Called seas or mare in Latin, because they thought they looked like seas

  13. Moon – Formation of Seas • “Lunar Lakes” • StarDate: October 15, 2005 • # 32 • http://www.StarDate.org

  14. The Moon – Lunar Cycles • A complete lunar cycle takes 29½ days • Four main phases – new, first quarter, full and last quarter • “Backyard astronomers describe the phases in terms of the Moon’s ‘age’ in days after the new phase.” (NightWatch, p. 138) • First quarter – around 7 days old • Full Moon – around 14 or 15 days old • Last quarter – around 22 days old

  15. Phases of the Moon • New Moon – the point when the Moon is closest to being between Earth and the Sun • It is during the day so we can’t see it • Waxing crescent – “waxing” means it is getting larger • First Quarter – around 7 days old • Waxing gibbous – “gibbous” means “humpbacked” Keith’s Moon Page – http://home.hiwaay.net/~krcool/Astro/moon/

  16. Phases of the Moon • Full Moon – the Earth is between the Moon and the Sun • Rises at the same time the Sun sets • Waning gibbous – “waning” means that it is getting smaller • Last Quarter – around 22 days • Waning crescent Keith’s Moon Page – http://home.hiwaay.net/~krcool/Astro/moon/

  17. StarDate Magazine, January/February 2005

  18. Phases of the Moon • Moon phase animation: www.MoonAni.gif

  19. Phases of the Moon • Another Moon phase animation: • http://www.astro.wisc.edu/~dolan/java/MoonPhase.html

  20. Moon Phase Activity • Simulating Moon phases with white balls and overhead projector. www.shadowsofoz.net

  21. Sun-Earth-Moon Motion • Simulating how the Moon rotates around the Earth, and both rotate around the Sun

  22. Sun-Earth-Moon Motion • Simulating how the Moon rotates around the Earth, and both rotate around the Sun www.areavoices.com

  23. Synchronous Rotation • Simulating Synchronous Rotation of the Moon around the Earth • As the Moon rotations around the Earth, the same face of the Moon is always facing the Earth • This is caused by the Earth’s gravity

  24. Synchronous Rotation • “Which diagram indicates synchronous rotation?” http://burro.cwru.edu

  25. Synchronous Rotation • “In synchronized rotation, what is synchronized?” • The rotation is synchronized with the revolution

  26. The Moon • The Moon’s orbit is not circular but elliptical, so its size can vary from our point of view • Perigee = the point in its orbit when the Moon or satellite is nearest to the Earth • Apogee = the point when it is farthest from the Earth – appears smaller • The full Moon can look larger or smaller depending if it is at perigee or apogee • 13% larger or smaller At apogee At perigee http://www.fourmilab.ch/earthview/vplanet.html Webster’s Dictionary

  27. The Moon www.antwrp.gsfc.nasa.gov/apod (October 25, 2007)

  28. The Moon – how far away? • Since it has an elliptical orbit • 221,463 miles (perigee) to 251,968 miles (apogee) • It takes 2.6 seconds for a laser beam to return to Earth (aimed at mirrors places on the Moon by Apollo astronauts) • So, 1.3 light-seconds away

  29. The Moon – how far away? • The large appearance of the Full Moon in the sky is often deceiving and it is easy to assume the Moon is very large and relatively close to the Earth • Demonstration of the relative size of the Moon to the Earth and the distance between the two.

  30. The Moon – how far away? • The diameter of the Moon is ¼ the diameter of the Earth • This photo is in scale • The distance between the Earth and Moon is 30x the diameter of the Earth http://moontag.files.wordpress.com

  31. The Moon • The best time to look at the Moon with binoculars or telescope is when the Moon is: • Between the waxing crescentand first quarter • Can see the most detail along the terminator

  32. The Moon • The terminator = the line dividing the illuminated and un-illuminated portions of the Moon. • The most interesting place to see detail and interesting features • Notice how you can see the craters along the terminator http://www.nineplanets.org/luna.html

  33. The Moon • The hardest time to see detail on the Moon is during a full Moon • Too much light and the details look flat • Best to use a Moon filter on a telescope when viewing between the first quarter and last quarter • The magnified Moon is very bright

  34. Viewing the Stars with the Moon present • The Moon, although interesting in itself, is a source of light pollution, making it difficult to view the stars when present. • The time period most effected is when the Moon is between the first quarter and full phases. • This is when the Moon is the brightest during the early evening – prime stargazing time

  35. Viewing the Stars with the Moon present • A few days after the Moon is full, it doesn’t interfere as much, since it is rising later each day • Rising after the prime stargazing time • “From night to night, the Moon moves about 12 degrees eastward. As a result, the Moon rises in the east an average of 50 minutes later each day.” (NightWatch, p. 141)

  36. The Moon’s movement across the sky • The Moon moves 12.2 toward the east each day • 360 = 12.2/day 29.5 days • The Moon rises about 50 minutes later each day • 1440 minutes* / day = 48.5 minutes 29.5 days * 24 hours x 60 minutes = 1440 minutes

  37. Moon – What to look for • Sea of Serenity (Mare Serenitatis) • Sea of Tranquility (Mare Tranquillitatis) • Where the first Apollo space craft landed • July 20, 1969 • Theophilus – 100 km (161 mi.) across, with walls that soar 4,000 meters (12,000+ feet) up from base • Casts magnificent shadows Nightwatch, p. 141

  38. Moon – What to look for • Copernicus – 93 km (150 mi.) across • “Considered by many observers to be the most awesome lunar feature” (p. 140) • Tycho – 85 km (137 mi.) across • “Tycho appears to be the hub of a system of white spoke…” (p. 140) • Clavius – 230 km (370 mi.) across, with a number of smaller craters within Nightwatch, p. 140

  39. Moon – What to look for • Plato • Copernicus • Tycho www.lpod.org

  40. Apollo Missions to the Moon http://www.nineplanets.org/luna.html

  41. “That’s one small step for man; one giant leap for mankind.”Neil Armstrong, July 20, 1969 Neil Armstrong’s shadow on the Moon, July 1969 http://www.youtube.com/watch?v=RMINSD7MmT4

  42. The Moon • Apollo missions to the Moon Apollo 11 – July 16-24, 1969 (First mission) • July 20, 1969 – landed on the Moon (Sea of Tranquiility) • Apollo 16 – April 16-27, 1972 • Apollo 17 – Dec. 7-19, 1972 (Last mission) http://home.hiwaay.net/~krcool/Astro/moon

  43. The Moon • Apollo missions to the Moon • Apollo 12 – Nov. 14-24, 1969 • Apollo 13 – April 11-17, 1970 – safe return • Apollo 14 – Jan. 31-Feb. 9, 1971 • Apollo 15 – July 26-Aug. 7, 1971 http://home.hiwaay.net/~krcool/Astro/moon/

  44. Lunar Eclipse • A lunar eclipse occurs when the Earth moves directly between the Moon and the Sun • Only when Moon is full www.media3.washingtonpost.com

  45. Lunar Eclipse • It appears coppery or red because light from the Sun is bent by the Earth’s atmosphere, and most of the blue light is removed • Same reason sunsets look red • Last Lunar eclipse was on February 20, 2008 • Next one: December 21, 2010, 3:17 am Explorations: An Introduction to Astronomy, Thomas T. Arny, p. 200

  46. www.nasa.gov http://www.youtube.com/watch?v=IVkkCVh5t0E

  47. Critical Thinking Question • What scientific breakthrough was aided by an understanding of lunar eclipses?

  48. Lunar eclipse – August 28, 2007

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