A tour of the Night Sky: Astronomy Made Simple

Dr. Nathan Miller

UWEC Department of Physics & Astronomy

Goals of class:Goals of class:1. Learn how stars, sun, moon and planets 1. Learn how stars, sun, moon and planets move through the skymove through the sky

2. Understand how Copernicus and Co. 2. Understand how Copernicus and Co. (1473-1543) used that alone to figure out the (1473-1543) used that alone to figure out the way the solar system is put together way the solar system is put together

Things you would study in a Things you would study in a medieval university:medieval university:

• The Trivium:– Grammar – Rhetoric – Logic

• The Quadrivium:– Arithmetic – Geometry – Music– Astronomy (Note: Not a trivial subject!)

Hogwarts classesHogwarts classes

• Herbology

• Potions

• Charms

• Muggle Studies

• Care of Magical Creatures

• Defense Against the Dark Arts

• Astronomy

Points of Light in the SkyPoints of Light in the Sky

A picture of 6 planets: A picture of 6 planets:

Jupiter

MarsSaturn Venus

Mercury

Two large Two large sources of lightsources of light

Moon, Venus, SpicaMoon, Venus, Spica

Practical Astronomy: The Motions Practical Astronomy: The Motions of the Starsof the Stars

Understanding the Motion of the Understanding the Motion of the Stars using the Celestial SphereStars using the Celestial Sphere

Note: The celestial sphere is not at some specific location. It is just an imaginary sphere used to discuss

the locations of and angles between the stars.

Atlas holding a celestial globe

(Roman copy of 200 BC

Greek original)

Exercise 1: Planisphere: Star Motions

Celestial Navigation:Celestial Navigation:

From ancient timesFrom ancient times

To recent times

To orient yourself and fix your To orient yourself and fix your location, want:location, want:

1. Cardinal directions1. Cardinal directions2. Latitude2. Latitude3. Longitude 3. Longitude

•YOU ARE HERE

Celestial Navigation: Determine Celestial Navigation: Determine your location on earth by your location on earth by

measuring the elevations of measuring the elevations of stars above the horizonstars above the horizon

This works because at the same This works because at the same moment in time, every location moment in time, every location on earth sees a unique view of on earth sees a unique view of

the sky.the sky.

Instruments: Instruments: Mariner’s Astrolabe:Mariner’s Astrolabe:

Sextant:Sextant:

Step 1: Use Polaris to locate Step 1: Use Polaris to locate due northdue north

Step 2: Measure angle of Step 2: Measure angle of Polaris above your horizonPolaris above your horizon

Height of Polaris above the Height of Polaris above the horizon = your lattitudehorizon = your lattitude

Person Standing at North Pole

Zodiacal Constellations: 12 constellations on dotted line on the planisphere. They tell you

which direction you are looking out into space

Exercise 2: Stars Around the World

Exercise 3: Celestial Navigation