Q Purpose This activity assesses students' ability to apply learning objective #2: Use Hubble's Law to intercompare distances to galaxies from redshift measurements. I will grade and discuss your answers after the discussion period has closed. Reminder: Dr. Weil's Math Shortcut You downloaded the pdf file with an introduction and examples in Week 3. Here it is again: Beginning Dr Weil's Shortcut 21.pdf Download Beginning Dr Weil's Shortcut 21.pdf There is also a video to help you in Week 3. The two sentences you need to remember are: Both on top, do same thing. One on top and one on bottom, do opposite. Directions Only a student's first post can be counted because everyone else's posts are visible after you post the first time. The Canvas Student GuideLinks to an external site. provides instructions for replying to a discussion postLinks to an external site.. Part 1: Due Thursday at 9pm. 1. Was it easy for scientists to measure the value of the Hubble constant? Why or why not? 2. Galaxy X in the Virgo Cluster has a cosmological redshift in its spectrum of z = 0.003 indicating it is moving away from us at 900 km/s. Galaxy Y has z = 0.015 a) Using z = v/c and our math shortcut, how fast is Galaxy Y moving away from us? (You can review the method in Box 23-2.) b) Using Hubble’s Law v = H0d: Which galaxy, X or Y, is further away from us? How many times further? c) Which galaxy's light takes longer to reach us? 3. The distance to a galaxy in the Fornax Cluster is 62 million light years. How long does it take its light to reach us? Why does it take this long? 4. Which galaxy is moving away from us faster? Galaxy P at 7 x108 light years away Galaxy Q at 3 x109 light years away Part 2: Due Sunday at 9pm. On Thursday at 10pm, you will be assigned a student for whom you will provide a peer review. For each answer, you may indicate whether you think the student has answered correctly or incorrectly. If incorrect, you may explain why and what the right answer is. If you choose to do this, please don't try to grade your peer review student but just guide them if you wish. If you believe that they answered correctly but your answer was incorrect, please explain what you learned from their answer. You may also or instead discuss what you thought of this week's content, what you learned, and what was confusing. At least four full, thoughtful sentences are required for full credit. Remember, the rubric mentioned below is for you to see how to be successful on an assignment and for me assess your work; students cannot and should not use it to grade anyone. Peer reviews are not for giving grades to the students. Once your student for peer review is assigned, the notification you receive allows you to access them to leave your comments in the comments sidebar. I am looking for gentle, guiding advice, questions, praise and other scientifically relevant comments. I am hoping that looking at each other's work will help you improve yours! You can view peer review notifications in Canvas in the Recent Activity Stream, the To Do list, and from the individual discussion page. Once peer reviews are assigned, you can also be notified according to your Canvas notification preferences. Click on "Review Now." To complete the peer review you must review the student's discussion reply and add a comment in the comment sidebar. Don't use the Rubric mentioned below for peer reviews; that is just for you to see how I will grade each discussion. Canvas looks like it will force you to use the Rubric BUT it will not record your peer review if you write it in the Rubric and you will earn no points if you fill it in! The peer review must be written in the comments sidebar. Rubric To view grading criteria, click on the three dots in the upper right and select Show Rubric. After I have graded your Discussion, visit your Grades page and click on the Rubric icon at the right side for this Discussion to see my personal comments to you.