* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download A1 F2015 Seasonal.key
Dialogue Concerning the Two Chief World Systems wikipedia , lookup
X-ray astronomy satellite wikipedia , lookup
Astronomical unit wikipedia , lookup
Copernican heliocentrism wikipedia , lookup
Corvus (constellation) wikipedia , lookup
Space Interferometry Mission wikipedia , lookup
Geocentric model wikipedia , lookup
Astrobiology wikipedia , lookup
International Ultraviolet Explorer wikipedia , lookup
Patronage in astronomy wikipedia , lookup
Chinese astronomy wikipedia , lookup
Archaeoastronomy wikipedia , lookup
Timeline of astronomy wikipedia , lookup
Constellation wikipedia , lookup
Astronomy in the medieval Islamic world wikipedia , lookup
International Year of Astronomy wikipedia , lookup
Hebrew astronomy wikipedia , lookup
History of astronomy wikipedia , lookup
Observational astronomy wikipedia , lookup
Night Sky II Annual Motion Seasons Planetary Motion Astronomy 1 — Elementary Astronomy LA Mission College Spring F2015 Quotes & Cartoon of the Day “You will certainly not doubt the necessity of studying astronomy and physics, if you are desirous of comprehending the relation between the world and Providence as it is in reality, and not according to imagination.” — Maimonides “Even if 'going retrograde' or 'moving into Aquarius' were real phenomena, something that planets actually do, what influence could they possibly have on human events? A planet is so far away that its gravitational pull on a new-born baby would be swamped by the gravitational pull of the doctor's paunch.” — Richard Dawkins Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 Quotes & Cartoon of the Day Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 Announcements Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 Last Class • • • Intro to the Night Sky Apparent Magnitude Diurnal Motion • LT “Position” time permitting Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 This Class • • LT Position Annual Motion • • • Zodiac Seasons Planetary Motion (time permitting) Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 LT “Position” Astronomy 1 — Elementary Astronomy LA Mission College Spring F2015 WARM UP QUESTION FOR LT POSITION You observe a star rising directly in the East. When it reaches its highest position above the horizon, where will it be? A. high in the northern sky B. high in the eastern sky C. high in the southern sky D. high in the western sky Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 LECTURE-TUTORIAL “POSITION” PP 1-2 LT Position pp 1-2 1) Is the horizon shown a real physical horizon or an imaginary plane that extends from your observing location on Earth out to the stars? 2)Can the observer shown see a star when it is located below the horizon? Why or why not. 3)Is either Star A or Star B even in an unobservable position? If so, which position(s)? 4)When a star travels from a position below the observer’s horizon to a position above the observer’s horizon, is that star rising or setting? 5)When a star travels from a position above the observer’s horizon to a position below the observer’s horizon, is that star rising or setting? Astronomy 1 - Elementary Astronomy LA Mission College Figure 1 Levine F2015 LT Position pp 1-2 6)Star A is just visible above your eastern horizon at Position 1. At which of the numbered positions is it just visible above your western horizon? 7)At which position(s) if any, does Star B rise and set? 8)Two students are discussing their answers to Question 7. Student 1: Locations B1 and B3 are on my horizon because they are rising and setting just like A1 and A3. Student 2: Figure 1 shows that Star B is as low as it will get when it is just above the northern horizon at B4. So Star B never goes below the horizon. Figure 1 Do you agree or disagree with either of both of the students? Explain your reasoning. Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 LT Position pp 1-2 9)Label the directions north, south, east and west on Figure 1. Check your answer with another group. Figure 1 Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 LT Position pp 1-2 10)For each indicated position, describe where in the sky you must look to see the star at that time. Each description requires two pieces of information: the direction you must face (north, northeast, east, etc.) and how far above the horizon you must look (low, high or directly overhead). If you cannot see the star, state that explicitly. The descriptions for four positions are given as examples a) A1: east, low E N S W b) A2 c) A3 d) A4 e) North Star: north, high f) B1 g) B2: directly overhead Figure 1 h) B3: northwest, high i) B4 11)Does Star B ever set? Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 You observe a star rising directly in the East. When it reaches its highest position above the horizon, where will it be? A. high in the northern sky B. high in the eastern sky C. high in the southern sky D. high in the western sky Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 Let’s Practice If you observe the constellation Orion just above the horizon to the east, where will it appear to be an hour later? A. Closer to the horizon, to the East. B. Further above the horizon, to the East. C. In the same location. D. It will not be visible. Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 Stars that rise due East are above the horizon 12 hours. Circumpolar stars are always above the horizon. About how long do you think a star that risesEnearer the NE compass point could be aboveNthe horizon? S W A. 6 hours B. 12 hours C. 18 hours D. 24 hours Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 In the northern hemisphere, stars rise in the East, set in the West and travel counter-clockwise in circles around the North celestial pole. In the southern hemisphere, the stars A. rise in the West, set in the East and travel clockwise around the South celestial pole. B. rise in the East, set in the West and travel counterclockwise around the South celestial pole. C. rise in the East, set in the West and travel clockwise around the South celestial pole. D. rise in the West, set in the East and travel counterclockwise around the South celestial pole Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 Zodiac and Apparent Solar Motion Astronomy 1 — Elementary Astronomy LA Mission College Spring F2015 Apparent Solar Motion • • Due to Earth’s rotation, the sun & stars rise & set • When do we see stars? What does that mean? The Sun also appears to move against the background stars due to the Earth’s orbit around it Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 Visible Night Sky Changes • • We see stars in the direction away from Sun Which stars are visible at night changes over the orbit. Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 Like a merry-go-round that takes a year to make one rotation Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 Constellation Transiting at Midnight Changes • Midnight — direction opposite Sun Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 “The Sun is In” • Constellation “behind” the Sun Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 Apparent Solar Motion • The path the Sun appears to take is called the Ecliptic • • • The Ecliptic Plane is the plane in which the Earth orbits the Sun Planets appear near the ecliptic The zodiacal constellations lie near the Ecliptic Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 Apparent Solar Motion • Zodiac = imaginary belt about 8° on each side of the ecliptic • within which are the apparent paths of the sun, moon, and principal planets. • There are actually 13 classical constellations in the Zodiac • Ophiucus is between Scorpius and Sagittarius Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 Seasonal Constellations Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 Seasonal Constellations • Sun moves ~1 constellation per month. • • This is ~ Dec 1 The Sun is in Scorpius • • actually Ophiucus Taurus transits near midnight Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 Seasonal Constellations • Sun moves ~1 constellation per month. • • • • This is ~ Jan 1 The Sun is in ? ? transits near midnight Did Taurus rise earlier or later? Astronomy 1 - Elementary Astronomy Cancer Leo LA Mission College Levine F2015 Let’s Practice If The Sun appears in Virgo in the Fall (mid Sep to late Oct), approximately what time of year will it appear in Sagittarius? A. Fall B. Spring C. Summer D. Winter Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 One night, you see the rise at exactly ICE 2! star Sirius ASTRO 110/120! Levine Spring7:36 2013 PM. The following night it will rise Name:____________________! ! Date:__________ A. slightly earlier. B. at the same time. C. slightly later. Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 You go out tonight and see the brightest star inLevinethe ICE 2! ASTRO 110/120! Spring 2013 constellation Orion just rising above your eastern horizon at 10 PM. One week later at 10 PM this same star will be _____. Name:____________________! ! Date:__________ A. slightly higher in the sky. B. below your horizon. C. at the same height as before. D. setting on your western horizon. Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 What component of Earth’s motion causes the stars to rise earlier on successive nights? A. its rotation about its axis B. its orbit around the Sun C. the tilt of its rotation axis Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 SO... WHY DO WE HAVE SEASONS? We have Seasons because we are tipped! • The Earth’s axis is tipped 23.5° from the plane of it’s orbit. • • • Axial Tilt Axial tilt is the cause of seasonal variations It is NOT!!! Because the Earth’s orbit is elliptical! • • I bet you know something that tells you it can’t be this! The Earth’s orbit is almost circular AND the point of closest approach, perihelion, is in January Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 Axial Tilt Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 The Reasons for the Seasons • Like a gyroscope, the Earth “holds” it’s tilt as it travels around the Sun. The tilt does not rotate as the Earth revolves Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 Why does axial tilt drive the seasons? • • It’s about the transfer of Energy Specifically energy from Sun to Earth Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 Energy • Energy=capacity to start, stop, accelerate, turn, raise etc. something • • • microscopically or macroscopically capacity to “do work” — change the energy state of something E.g. • • • • • • • kinetic energy — energy of motion gravitational potential energy — boulder at top of hill thermal energy — motion of atoms and molecules chemical energy light energy electric potential energy — capacity to move electrons etc. Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 Energy from the Sun • Light or electromagnetic radiation • • • • • visible light infrared light ultraviolet light Net absorbtion of energy = heating Sun puts out same energy summer & winter, but in summer energy transfer is locally more efficient Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 Why does the tilt affect the Solar Energy Transfer? • • The length of the day • Summer days are longer than winter days The angle at which sunlight falls on the surface • The sun appears higher in the sky in summer and lower in winter • Sunlight is more direct in summer Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 The Length of the Day Northern summer = southern winter Northern winter = southern summer longer days mean more total exposure Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 The Angle of Sunlight Winter vs. Summer • Sun appears higher in the sky in summer &l ower in winter • • lower= light hits surface at steeper angle. Steeper angles = less concentrated light; dimmer Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 Terminology: Solstice & Equinox • Tilt toward or away from Sun — solstice • • • “sun stop” start of winter or summer Tilt parallel to Sun — equinox • • “Equal night” start of spring or fall Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 Direction of Sunrise and Sunset are also affected • At summer solstice, the Sun rises N of due E (in the northern hemisphere) • • At winter solstice the Sun rises S of due E This is the same reason the day length varies Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 Let’s Practice Which lettered position (A-E), in the image below, best represents the location on Earth that is experiencing winter in the Northern Hemisphere? Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 If Earth were tilted more (60° rather than 23.5°), then during winter at your location you would _____ compared to what you experience during winter now. A. experience cooler temperatures B. experience warmer temperatures C. not experience any significant change in temperature Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 Planets... the Wanderers Astronomy 1 — Elementary Astronomy LA Mission College Spring F2015 Planets... the wanderers • It was a warm summer evening in ancient Greece.... Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 Apparent Motion of Planets • Indeed originally named for their “wandering” movement • • Most of the time rise a bit later each night • • move eastward against the background stars Sometimes appear to go “backwards” for a while • • • “Late Old English planete, from Old French planete (Modern French planète), from Late Latin planeta, from Greek planetes, from (asteres) planetai "wandering (stars),..." i.e. rise earlier each night/go westward This is called retrograde motion We will explain how this works later in the course Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 Mars and Retrograde Motion QuickTime movie from Dr. Ted Snow's web site at The University of Colorado, Boulder.) Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 Let’s Practice For how many days was this planet in retrograde motion? May A. 10 days B. 12 days C. 15 days D. 17 days E. 32 days Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 On which date would the planet appear to rise in the west? May A. March 1 B. March 31 C. April 5 D. April 12 E. Never Ever, Never, Ever, EVER!!!!!!! Never, Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 WRAP-UP Topic for Next Class • Night Sky III • • Lunar Phases Eclipses Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 Reading Assignment • Ch 2 in either text Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015 Homework • None Assigned yet Astronomy 1 - Elementary Astronomy LA Mission College Levine F2015