# sun - 1 Announcements Homework#5 due today Review on Monday...

This preview shows pages 1–3. Sign up to view the full content.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 1 Announcements - Homework #5 due today - Review on Monday 3:30 – 4:15pm in RH103 - Test #2 next Tuesday, Oct 11 - No makeups Review for Test #2 Oct 12 Topics: • The Solar System and its Formation • The Earth and our Moon • The Terrestrial Planets • The Jovian Planets • Moons, Rings, Pluto, Comets, Asteroids, Dust, etc. • The Sun Methods • Conceptual Review and Practice Problems Chapters 4 - 9 • Review lectures (on-line) and know answers to clicker questions • Try practice quizzes on-line • Come talk to me in office hours (Monday 9-11am) •Bring: • Two Number 2 pencils • Simple calculator (no electronic notes) Reminder: There are NO make-up tests for this class The Sun The Sun in X-rays over several years The Sun is a star : a shining ball of gas powered by nuclear fusion . Luminosity of Sun = 4 x 10 33 erg/s = 1 L Sun (amount of energy put out each second in form of radiation, = 10 25 40 W light bulbs) We receive 1400 W/m 2 Mass of Sun = 2 x 10 33 g = 330,000 M Earth = 1 M Sun Radius of Sun = 7 x 10 5 km = 109 R Earth = 1 R Sun Temperature at surface = 5800 K => yellow (Wien’s Law) Temperature at center = 15,000,000 K Average density = 1.4 g/cm 3 Density at center = 160 g/cm 3 Composition: 71% of mass is H 27% He 1% Oxygen 1% everything else Rotation period = 27 days at equator 31 days at poles DEMO: Switch on the SUN! Sun during solar eclipse Jan 2011 The Interior Structure of the Sun (not to scale) Let's focus on the core, where the Sun's energy is generated. Core of the Sun Temperature : 15 million K (1.5 x 10 7 K) Density: 160 gm/cm 3 , 160 times that of water, 10 times the density of lead 2 Review of Atoms and Nuclei Hydrogen atom : _ + proton electron _ + + _ Helium atom : The proton is the nucleus The nucleus is 2 protons + 2 neutrons What binds the nuclear particles? The “strong” nuclear force. Number of protons uniquely identifies element. Isotopes differ in number of neutrons . Review of Ionization + Radiative ionization of H _ Energetic UV Photon "Collisional Ionization" of H + _ _ + Clicker Question: In overall composition the Sun is most like what planet? A: Mercury B: Venus C: Earth D: Jupiter Clicker Question: What is an ion?...
View Full Document

## This document was uploaded on 12/13/2011.

### Page1 / 7

sun - 1 Announcements Homework#5 due today Review on Monday...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online