Astronomy 1010-H Planetary Astronomy Fall_2015 Day-5

Course Announcements Smartworks Chapter 1: Due Fri. (Sep. 4) Read Chapter 2.1, 2.2 Next week: Dark Night Observing on Tues. 9/8 & Thur. 9/10 Thurs. 9-3:    Meeting; watch for signs. Thurs. 9-3: “1 st Thursday Art Walk” downtown, 5pm Sat. 9-5: Football vs Mercer, 4pm; Tailgate at 1pm

Definitions & Terms -1 Math: A useful tool for investigating science and torturing students. Asterism: A pattern of stars that appears to form a familiar object. It may contain stars from more than one constellation, or be a small piece of a single constellation (example – the Big Dipper).

 Science discovers patterns in nature.  Mathematics is the language of patterns.  Most phenomena work regularly and predictably.

Constellations – the 88 semi- rectangular regions that make up the sky Northern constellations have Latinized Greek- mythology names: Orion, Cygnus, Leo, Ursa Major, Canis Major, Canis Minor Southern constellations have Latin names: Telescopium, Sextans, Pyxsis

An Important Assumption The cosmological principle: “There is nothing special about our place in the universe.” On one level: Our view from the Earth is not special or unique. Distant objects should be like nearby ones which we can study in detail. On another level: Matter and energy obey the same physical laws everywhere.

To make sense of what we see: The Cosmological Principal

Colored Card Question: Principles Which of these is a restatement of the cosmological principle? A.The universe is the same everywhere. B.The same rules work everywhere in the universe. C.There are no phenomena remaining to be discovered.

MATH TOOLS

 Mathematics works when used to describe nature and its patterns.  Basic Tools: Scientific Notation: handling large or small numbers Ratios: comparing Geometry Algebra: representation Proportionality: understanding the relationships between quantities. MATH TOOLS 1.1

 Graphs are used to represent relationships between quantities.  Can be linear or nonlinear.  For linear, the slope is the change of the vertical axis divided by the change of the horizontal axis. MATH TOOLS 1.2

Dealing with very large and small numbers Scientific Notation 4,500,000,000,000,000 = 4.5x = 2.8x On calculators…look for the “EXP” key or the “EE” key

Common Prefixes centi = 0.01 = (c) milli = = (m) micro = = (  ) nano = = (n) kilo = 1,000 = 10 3 (k) mega = 1,000,000 = 10 6 (M) giga = 1,000,000,000 = 10 9 (G) tera = 1,000,000,000,000 = (T)

Time to Re-Calibrate

Use the Big Dipper in the northern sky as a way to find other groups of stars

Use Summer Triangle to find constellations during evenings

Use Winter Triangle to find constellations during evenings

Stuff in Chapter 2 Coordinates Position Daily Motion (spin of Earth on its axis) Visibility of the sky Year Motion (Earth orbits the Sun) Seasons (tilt of the Earth’s axis) Precession of the equinoxes Motion and phases of the Moon Eclipses

Coordinates

Celestial Sphere Celestial Sphere Rotation Celestial Sphere Star A Star B Figure 2 Horizon Is the horizon shown a real physical horizon, or an imaginary plane that extends from the observer and Earth out to the stars? Can the observer shown see an object located below the horizon? Is there a star that is in an unobservable position? When a star travels from being below the observer’s horizon to being above the observer’s horizon, is that star rising or setting? Position

Tutorial: Position – p.1 Work with a partner Read the instructions and questions carefully Discuss your answers with each other Come to a consensus answer you both agree on If you get stuck or are not sure of your answer ask another group If you get really stuck or don’t understand what the Lecture Tutorial is asking as one of us for help

Concept Quiz In what direction is the observer facing? A) toward the South B) toward the North C) toward the East D) toward the West Celestial Sphere Celestial Sphere Rotation Celestial Sphere Star A Star B Horizon

Concept Quiz Where would the observer look to see the star indicated by the arrow? A. High in the Northeast B. High in the Southeast C. High in the Northwest D. High in the Southwest Celestial Sphere Celestial Sphere Rotation Celestial Sphere Star A Star B Horizon

Nightly Motion of the Stars Imagine looking toward the North. What do stars appear to do over the course of an evening?

Nightly Motion of the Stars Looking North: Stars appear to move counter- clockwise around the stationary North Star (Polaris) – we call these circumpolar stars.

Earth’s rotation causes the Sun, Planets, Moon and stars to appear to move when viewed from Earth Photo: Dr. Spencer Buckner

Nightly Motion of the Stars Celestial Sphere Celestial Sphere Rotation Celestial Sphere Star A Star B Figure 2 Horizon

Circumpolar Stars Circumpolar stars seem to move counter-clockwise around the stationary North Star. These constellations and stars are visible any night of the year in the NORTHERN sky because they never rise or set! Examples: Ursa Major, Ursa Minor, Draco, Cepheus, and Cassiopeia

Tutorial: Motion – p.3 Work with a partner Read the instructions and questions carefully Discuss your answers with each other. Come to a consensus answer you both agree on If you get stuck or are not sure of your answer ask another group If you get really stuck or don’t understand what the Lecture Tutorial is asking ask one of us for help

Two-Minute Essay  My name is…  The scientist (living or dead, but real) I would most like to meet is: