Eclipses and the Phases of the Moon: ASTR 111 – 003 Fall 2007 Lecture 3 - Prof. Jie Zhang, Study notes of Astronomy

Download Eclipses and the Phases of the Moon: ASTR 111 – 003 Fall 2007 Lecture 3 - Prof. Jie Zhang and more Study notes Astronomy in PDF only on Docsity! > dt Eclipses and the Motion of the Moon Chapter Three ASTR 111 – 003 Fall 2007 Lecture 03 Sep. 17, 2007 Introducing Astronomy (chap. 1-6) Introduction To Modern Astronomy I: Solar System Ch1: Astronomy and the Universe Ch2: Knowing the Heavens Ch3: Eclipses and the Motion of the Moon Ch4: Gravitation and the Waltz of the Planets Ch5: The Nature of Light Ch6: Optics and Telescope Planets and Moons (chap. 7-15) Chap. 16: Our Sun Chap. 28: Search for Extraterrestrial life • Waxing crescent moon – When you see a waxing crescent moon in the evening sky, what time is it? and where is the Moon? • Full moon – What time does it rise? What time does it set? And where? – When you see a full Moon overhead, what is the time? • When the Sun sets, where is the first quarter moon? • When the Sun sets, where is the third quarter moon? Phases of the Moon Synchronous Rotation of Moon • Observations show that the Moon always keeps the same hemisphere, or face, toward the Earth. • Synchronous rotation: the Moon makes one rotation in exactly the same time that it makes one orbit around the Earth. Thus we only see the same face. 0303002_synchronousMoon.swf FLASH Synchronous Rotation of Moon If the Moon did not rotate, In fact the Moon does rotate, we could see all sides of the Moon and we see only one face of the Moon Moon’s orbit Tad) eter eRe) Light from Sun a reais Earth EIT ede Lig . Gere > M79) i SE) Lemay from Earth; Rae hclg blue crater NER lL a Dearly not visible the red crater is visible Peele ane mat ee) Light from Sun ee ated Light from Sur tele eu Solar and Lunar Eclipses Gere edd Solar and Lunar Eclipses • Eclipses occur – when the Sun, Earth and Moon all lie exactly along a straight line, the shadow of Earth (Moon) falls on the Moon (Earth) • Lunar eclipse: the Moon passes through the Earth’s shadow – The Earth is between the Sun and the Moon – The Moon is at full phase – The full moon appears quite dim during lunar eclipse • Solar eclipse: the Earth passes through the Moon’s shadow – The Moon is between the Sun and the Earth – The Moon is at new phase – The Sun sometimes fully disappears in the clear sky during the solar eclipse. Eclipses do not Occur Every Month • The plane of the Moon’s orbit is tilted about 5° with respect to the plane of the Earth’s orbit (so called ecliptic plane) • At new and full phases, the Sun, Earth and Moon are often not along a straight line. • There are a few solar and lunar eclipses per year. • The maximum number (combined) in a single year is seven Lunar eclipses • Total lunar eclipse – The Moon travels completely into the umbra • Partial lunar eclipse: – Only part of the Moon passes through the umbra Lunar eclipses • Totality: the period when the Moon is completely within the Earth’s umbra, which is a few times larger than the size of the Moon – Totality can last as long as 1 hour and 42 minutes. • A lunar eclipse can be seen at any place on Earth where it is nighttime. Solar eclipses • Total solar eclipse • Partial solar eclipse • Annular solar eclipse Total solar eclipse Annular solar eclipse Solar eclipses 60°N 30°N Latitude o 30°S 60°S 180°W 150°W 120°W 90°W 60°W 30°W 0° 30°E 60°E 90°E 120°E 150°E Longitude Eclipse Paths for Total Solar Eclipses, 1997-2020 Solar eclipses table 3-2 | Solar Eclipses, 2004-2008 2004 April 19 2004 October 14 2005 April 8 2005 October 3 2006 March 29 2006 September 22 2007 March 19 2007 September 11 2008 February 7 2008 August 1 Partial Partial Annular and Total Annular Total Annular Partial Partial Annular Total Antarctica, southern Africa Northeast Asia, Hawaii, Alaska New Zealand, North and South America Europe, Africa, southern Asia Africa, Europe, western Asia South America, western Africa, Antarctica Asia, Alaska South America, Antarctica Antarctica, eastern Australia, New Zealand Northeast North America, Europe, Asia 74% eclipsed 93% eclipsed Annular along part of path; maximum duration of totality Om 42s Maximum duration of totality 4m 7s 87% eclipsed 75% eclipsed Maximum duration of totality 2m 27s Eclipse predictions by Fred Espenak, NASA/Goddard Space Flight Center. All dates are given in standard astronomical format: year, month, day. Final Notes on Chap. 3 • Covers section 3-1 to 3-5. Section 3-6 is not covered.