L6 Reflectance Written and graph 021123

pdf

School

University of Washington *

*We aren’t endorsed by this school

Course

150

Subject

Electrical Engineering

Date

Feb 20, 2024

Type

pdf

Pages

Uploaded by gjackson55

Giles Jackson 02/11/2023 ASTR 150 Introduction to Reflectance Spectra Using the data presented in Graph 1 above, answer the following six (6) questions. Question 1 (4 pts): Which sample in filter #1 is the brightest of the four samples? Is this also true for filter 2? If not, what has change. Given your understanding of the surfaces of worlds in the Solar System, is it surprising that this sample is the brightest (please explain your response)? The brightest sample in filter 1 is anorthosite; the brightest filter sample in filter 2 is Green Leaf. This is not surprising since healthy plants have a high reflectance in the near infrared between 0.7 and 1.3 µm. This is primarily due to the internal structure of plant leaves. Question 2 (4 pts): Which sample in filter #2 is the darkest of the four samples? Is this also true for filter 1? If not, what has changed. Given your understanding of the surfaces of worlds in the Solar System, is it surprising that this sample is the darkest (please explain your response)? The darkest sample in filter 2 is Basalt and this is also true for filter 1. Basalt is easily recognizable due to its dark color (black) which is harder for light to pass. Assume that you only have data from filters #1 and #2 in Graph 1- in other words, pretend you can't see the data given between or outside of these filters. For the following four questions, compare the appearance of the samples in the filters indicated in each question. Question 3 (3 pts): Can you distinguish anorthosite from basalt easily in either filter? Briefly explain why or why not for each filter? Does this make sense knowing what you know about these samples? Yes, anorthosite is brighter in filter 1 and 2. Question 4 (4 pts): Can you distinguish olivine from green leaf in filter #1? Explain your response. Let's pretend we have third filter, and it is centered at 760 nm. Would you have a better chance of distinguishing between olivine and green leaf now? Explain your response. Yes, olivine is brighter than green leaf in filter 1; At about 760 nm, olivine intersects with green leaf, so it would be difficult to distinguish. Question 5 (4 pts): You can clearly distinguish basalt from green leaf in both filters #1 and #2. Clearly green leaf is much brighter that basalt in filter two. Can you think of a reason why green leaf is so much brighter (Don't Google for the answer. Think about the samples and come to a conclusion on your own - you will not be graded on right/wrong, but on the quality of your response/argument). As green leaf moves through the wave length it generally gets brighter, whereas basalt is constant and remains dark. Question 6 (3 pts): Let's pretend I told you I have a sample of some material and it's reflectance is 0.20 as observed in filter #1. What would you conclude the likely composition of my material to be? If I said the sample I have is the same reflectance in filter #2 would draw the same conclusion about my sample's composition? Explain your response. I would conclude the material observed in filter 1 at .20 to be green leaf. For the same reflectance in filter 2, I would be closer to choosing olivine although it would be a little lighter than Greenleaf in the first filter. Question 7 (3 pts): Consider the entire reflectance spectrum of Surface A . What is its most likely composition? How confident are you in your response (i.e. could it actually be some other composition?)? The composition looks to be a mix of olivine and green leaf, not confident in answer, it could very well be something else. Question 8 (3 pts): Consider the entire reflectance spectrum of Surface B . What is its most likely composition? How confident are you in your response (i.e. could it actually be some other composition?)? The composition looks to be a mix of green leaf and basalt, not confident in answer, it could very well be something else. Question 9 (2 pts): Now assume that you could only see surface A through filter #1 . What color would the sample appear to be to your eyes? Why do you think it is this color? The sample would be yellow as this color corresponds best to the infrared scale. Question 10 (2 pts): Now assume that you could only see surface A through filter #2 . What color would the sample appear to be to your eyes? Why do you think it is this color? The sample would be black since anything over wavelength 750 is not visible to the eyes Question 11 (1 pts): What is the most likely reason for the change in albedo/material between the 1973 and the 1983 images? Mount St. Helen’s erupted. Question 12 (1 pts): In the 1973 image, Mount St. Helens is surrounded by material that is bright in filter #2 . Based on your knowledge of the area and the data from Graph 1, what is this material? It has to be green leaf.

Giles Jackson 02/11/2023 ASTR 150 Question 13 (1 pts): In the 1983 image, Mount St. Helens is surrounded by material that is dark in filter #2 . Based on the data from Graph 1, what is this material? What other material might it be ( not necessarily from Graph 1 )? The material has to be basalt. Question 14 (1 pts): Assume it was possible to take a similar Landsat image in filter #2 of the city of Seattle 200 years ago. Would that image look different from one taken today? Why or why not - explain your response. Yes, it would be brighter (lighter albedo) due to the increase in trees, foliage, etc. Question 15 (1 pts): Assume it was possible to take a similar Landsat image in filter #2 of the Yucatan Peninsula 65 Myrs ago, several months after the KT Impact. How would that image look different from one taken today? Explain your answer . It would be darker due to a lower albedo. PLEASE SEE GRAPH BELOW. I DON’T HAVE A PRINTER, SO IT IS NOT DRAWN TO SCALE

Giles Jackson 02/11/2023 ASTR 150

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version