Chapter 2: Celestial Sphere, Seasons, Moon Phases and Eclipses - - PowerPoint PPT Presentation

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Chapter 2: Celestial Sphere, Seasons, Moon Phases and Eclipses - - PowerPoint PPT Presentation

May 18, 2023 29 likes •684 views

Chapter 2: Celestial Sphere, Seasons, Moon Phases and Eclipses ASTR/PHYS 1060: The Universe Fall 2019: Chapter 2 1 Name for the Class Llama (last years options) A) Sir Jeffrey McGoat, Esq. B) Space Ranger Goat C) Gerald The Space

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ASTR/PHYS 1060: The Universe Fall 2019: Chapter 2

Chapter 2: Celestial Sphere, Seasons, Moon Phases and Eclipses

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Fall 2019: Chapter 2 ASTR/PHYS 1060: The Universe

Name for the Class Llama

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A) Sir Jeffrey McGoat, Esq. B) Space Ranger Goat C) Gerald “The Space Odyssey” Goat Llama D) Goaterade / Goaty McGoatFace

(last year’s options)

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Fall 2019: Chapter 2 ASTR/PHYS 1060: The Universe

Name for the Class Llama

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A) Keanu Llama / John Wick B) Bob Lazar C) Cuzco Emperor of the Universe D) the G.O.A.T.

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Fall 2019: Chapter 2 ASTR/PHYS 1060: The Universe

Orienting Ourselves on the Earth

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It’s all just geometry and timing

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top view side view top view

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Important Points & Planes

  • n the Celestial Sphere

Project stars and planets on a sphere surrounding the Earth It is fictitious, but convenient for locating objects in the sky

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Orienting Yourself relative to the Celestial Sphere

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ASTR/PHYS 1060: The Universe Fall 2019: Chapter 2 8

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https://www.youtube.com/watch?v=IJhgZBn-LHg (Vsauce)

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Grab an ABCD page up front if you don’t have one

C D B A

(Hint: it looks like this)

  • Ch. 3 Reading Quiz to be completed in Canvas

due by 9:10am on Thursday First HW posted on website under: http://www.astro.utah.edu/~wik/courses/astr1060fall2019/ homework.html

Chapter 2: Celestial Sphere, Seasons, Moon Phases and Eclipses

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My primary reason for taking this course is…

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I have looked through a telescope I have seen the Milky Way

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Math Courses Previously Taken

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I am pretty good at algebra The value of C is…

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I believe that intelligent extraterrestrials exist I believe Earth has been visited by aliens

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If the north star is directly above Cuzco, Emperor of the Universe, (at their zenith), where are you on the Earth?

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A) North Pole B) Anywhere on the Equator C) Exactly at 0 degrees longitude

  • n the Equator

D) South Pole

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North Pole!

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Fall 2019: Chapter 2 ASTR/PHYS 1060: The Universe

If you’re 30 degrees north of the equator:

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Fall 2019: Chapter 2 ASTR/PHYS 1060: The Universe

At the Equator, where you can see the entire sky:

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Southern Hemisphere, same as in the north but relative to the South Celestial Pole

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What causes the seasons?

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A) Distance from the Sun B) Tilt of the Earth C) Distance from the Sun AND tilt of the Earth

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Fall 2019: Chapter 2 ASTR/PHYS 1060: The Universe

In SLC, where does the Sun set on the horizon?

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A) Same place every day B) A random (but predictable) place each day C) A different place each day of the year D) A different place each day for half the year, then repeating that pattern in reverse the second half

  • f the year
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Fall 2019: Chapter 2 ASTR/PHYS 1060: The Universe

In a group, try to answer: On what days does the Sun set in these locations?

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Fall/Spring Equinoxes September 21st March 20th Summer Solstice June 21st Winter Solstice December 21st

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Max altitude of the Sun determined by where we are on Earth and where the Earth is in its orbit

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The 2 reasons we have seasons

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Seasonal Poetry

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The two reasons we have seasons Are both due to the Earth’s tilt, When our nearest pole Points toward Sol Its light shines to the hilt And stays in the sky Like a too-long deployed spy At risk of committing treason!

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http://www.youtube.com/watch?v=Xm_Cn8-DCNc Where and when are we?

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Right now!

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https://www.timeanddate.com/worldclock/sunearth.html

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Fall Equinox

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https://www.timeanddate.com/worldclock/sunearth.html

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December Solstice

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https://www.timeanddate.com/worldclock/sunearth.html

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Where would you have to be for the sun to pass directly

  • verhead on June 21st?

A) At 23.5 degrees S latitude B) At 23.5 degrees N latitude C) At the north pole D) On the equator

Location: 40 deg N (same as SLC)

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Aside: Eratosthenes measures the Earth’s circumference in in 200 BC

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The Ecliptic

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Fall 2019: Chapter 2 ASTR/PHYS 1060: The Universe

The Ecliptic

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Why star rise/set times change

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About how many degrees does the Earth move in its orbit each day?

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Tonight, Vega (the brightest star in the constellation Lyra, part

  • f the summer triangle), will set at 6:55am. What time will it

set tomorrow night? A) 6:51am B) 6:55am C) 6:59am

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We need leap years because…

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A) Earth’s Axis is tilted B) Amy Adams and Matthew “Emperor of the Universe” Goode are delightfully funny together! C) The direction the Earth’s axis points slowly changes with time D) Earth does not go once around the sun in exactly 365 days

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We need leap years because…

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A) Earth’s Axis is tilted B) Amy Adams and Matthew Goode are delightfully funny together! C) The direction the Earth’s axis points slowly changes with time D) Earth does not go once around the sun in exactly 365 days —> 365.2422 days

Julian calendar was used for over 1000 years (leap day every 4 years). Every 400 years, the calendar is offset from the seasons by 3 more days. Gregorian Calendar (what we use today)

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Hey you, what’s your sign?

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Astrology is bunk!

(HINT: This will be an exam question.)

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Earth’s axis wobbles like a top: called Precession

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Earth’s axis wobbles like a top: called Precession

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Group Activity Time!

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When does the full moon rise?

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A) At Noon B) At Sunset C) At Midnight D) At Sunrise

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Can figure out roughly when the Moon will rise, given its phase, from this diagram alone

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Phases of the Moon

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Fall 2019: Chapter 2 ASTR/PHYS 1060: The Universe

Phases of the Moon

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gibbous crescent Waxing Waning

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Moon phases are easy to figure out once you have the right mental picture

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Draw the diagram!

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sunlight

Waning Gibbous

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Draw the diagram!

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sunlight

Gibbous =/= Crescent, so either

  • r

Waning = going away, Moon orbits same direction we rotate, so… Moon must be here!

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Draw the diagram!

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sunlight

Gibbous =/= Crescent, so either

  • r

Waning = going away, Moon orbits same direction we rotate, so… Moon must be here! When does it rise??? Horizon

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Galileo’s observations of the phases of Venus in 1610

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The apparent size of Venus correlates with its phase

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During what phase of the moon would you see a solar eclipse (the moon eclipses the sun)? How about a lunar eclipse (the earth eclipses the moon)? Why isn’t there an eclipse at every full and new moon?

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Solar Eclipses

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total annular

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Lunar Eclipse

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Eclipses are rare because the moon doesn’t orbit in the ecliptic

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The Moon’s orbit only crosses the ecliptic twice, so how many chances are there per year for a solar or lunar eclipse to occur?

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Is there a “dark side” of the Moon?

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Picture Credit: Apollo 16

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Nope - but there is a “far side”

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From the Clementine Satellite

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Tides

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How many high tides do we have per day?

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A) One B) Two C) Three D) Four

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strength of the tides depends on Moon phase Spring Tides Neap Tides

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Tidal Locking

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Tides on the Moon, caused by Earth, are stronger and have “locked” one side of the Moon toward the Earth How long does it take the Moon to rotate? These tidal forces are slowing down the rotation of the Earth, which means (to conserve angular momentum) that the Moon is moving away from us! 200 million years from now: a day will be 25 hours long 600 million years from now: no more total solar eclipses

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The two-faced Moon, in lame Mercator projection

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Lunar Reconnaissance Orbiter Mosaic

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The reason it’s two-faced is known, but how that happened is not!

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proto-Earth Mars-sized protoplanet

http://www.slate.com/blogs/bad_astronomy/2014/07/01/ the_moon_s_two_faces_why_are_they_so_different.html

Theory 1) two proto-Moons formed from collision, which later “gently” coalesced Theory 2) the Moon formed very close to the Earth, became tidally locked soon thereafter, and the heat from the Earth “evaporated” crust on the near side, which preferentially condensed on the cooler far side The Moon’s crust is thicker on the far side than the near side!