Welcome to Modern AstronomyFall 2007

• Initial pleasantries, who I am, who you are

• This should be the most interesting course you take in college

• National Solar Observatory

The Sun is more interesting some times (wait 5 years)

Example 1: The “Dark Matter”

Example 2: Arcturus (see it tonight)

Distance: 37 light years

Arcturus (bright star overhead) as an immigrant from another galaxy

The Milky Way (and other galaxies) catch and devour small galaxies

Details from the Syllabus

The Sky TonightThe Sky Tonight

• The Sun sets (7:48 PM) • Arcturus and Spica in the west

(stars)• Antares (star) and Jupiter in the

south• Vega (star) and the Milky Way

overhead• The Andromeda Nebula in the

east• Constellation of Scorpius• Constellations Internet Link

Tomorrow Morning: Total Eclipse of the Tomorrow Morning: Total Eclipse of the MoonMoon

Timetable for lunar eclipse

An Overview of the Solar System

Size scales in the solar system

• Basic unit: 1 meter • 1 kilometer = 1000 meters = 0.6214 miles• Diameter of Earth: 12756 kilometers (~ LA to

Sydney)• Closest object in space: Moon, 384,000 km

average distance• Most prominent object is astronomy: Sun, 149.6

million kilometers; 1 Astronomical Unit

demo

The Sun

Facts about the Sun

• Distance: 149.6 million kilometers = 1.496E+11 meters = 1 astronomical unit

• Radius = 695,990 kilometers = 6.960E+08 meters (109 times radius of Earth)

• If Earth were scaled to 1 foot globe size, the Sun would extend from goal line to 30 yard line at Kinnick stadium

• The Sun, not the planets (including Earth) is the dominant object in the solar system