Monday 4:00 – 4:55pm Sundquist Science Center E-109 Dr. Spencer Buckner

Office: SSC B – 326 Hours: M – F 12:30 – 2:30pm or by appointment Phone:

21 st Century Astronomy: Stars and Galaxies, 4 th Edition by Kay, Palen, Smith & Blumenthal Textbook If you don’t have a book there are older versions in the department library. Most of the problems are the same but check with me before using them.

Exams…………45%90 – 100…A Homework…….20%80 – 89…..B Projects………..30%70 – 79…..C Participation…….5%60 – 69…..D <60……….F

There will be three one-hour exams during the semester. The exams will be entirely problems similar to the homework problems. A formula sheet will be given out with the exam. Tentative exam dates are Monday February 22 Monday March 28 Monday May 4:00pm A scientific calculator will be required for the exams

Homework will be assigned from the Applying the Concepts at the back of each chapter in the 21 st Century Astronomy textbook. Additional problems from other sources will also be assigned to supplement the back-of-chapter questions. They will be due at the beginning of the next class meeting. First Homework set is due next week: Chapter 1 # 41, 42, 45, 49 & 53

There will be two projects assigned during the semester. The first project will be due February 29. The second project will be due at the final exam period (Monday May 4:00pm). In addition to a written report, you will make a short (10-15 minute) presentation on your project.

1 st Project Estimate the cost of the wasted energy in the image below For high resolution image see ws/earth-at-night.html#.VMlIqhBdXTp ws/earth-at-night.html#.VMlIqhBdXTp

How to work a problem Step 1: What are you trying to solve for? Step 2: What information are you given? Step 3: What equation(s) do you need to solve the problem? Step 4: Plug in the numbers and solve the problem Step 5: Check for reasonableness

The nearest star is Promixa Centauri, part of the triple star Alpha Centauri system. It is lightyears from Earth. If the fastest rocket ever made, the New Horizons spacecraft, could maintain its launch speed of km / s and it was launched at this star, how long would it take to reach Promixa Centauri?

Answer the first two questions Step 1: What are you trying to solve for? Travel time from Earth to Promixa Centauri. Step 2: What information are you given? Speed of spacecraft (16.26 km / s ) and distance from Earth to Promixa Centauri ( ly)

Step 3: what equation(s) do you need? Look for example problems in the chapter, in the appendix, in other textbooks or online. For this problem, the average velocity is the distance divided by the time So the time is the distance divided by the velocity

Unit Conversions Distance was given in ly and velocity was in kilometers per second. Consistent units are needed throughout. Convert distances to kilometers (or velocity to ly/sec). Conversion factors can be found in Appendix 2 A word about significant figures: your calculator may spew out 8 or 9 digits but most of them are meaningless. Your answer should always have the same number of digits as the least number of significant figures in the given data. You can carry more digits through the calculations but always round off at the end.

Step 4: Plug in numbers and solve d = x km v = km / s

Step 5: check for reasonableness Is this reasonable? How do I know if is reasonable?

One for you Use numbers from Appendix 2 and 4 in the back of the textbook to answer the following questions. The New Horizons spacecraft, fastest spacecraft ever launched, traveled the distance from the Earth to the Moon in 8.0 hours. If it maintained that speed and it was pointed in the right direction, how long would it take to reach Pluto? Sirius? New Horizons was launched on January 19, 2006

Step 1 & 2 Step 1: What are you being asked to solve for? Travel time to Pluto and Sirius Step 2: What information are you given? Travel time from Earth to the Moon: 8.0 hours From Appendix: distance from Earth to Moon: 384,400 km distance from Earth to Pluto: 5, x 10 6 km distance from Earth to Sirius: 8.60 lightyears

Step 3 Step 3: What equation(s) will you need to solve the problem? First, find the speed of the spacecraft and they use that speed to find the travel time to the two objects

Step 4: Plug in numbers For Pluto That puts it at Pluto in January 2020?!?

Step 4 for Sirius