Name_________________________

STUDENT INSTRUCTION AND ANSWER SHEET

Activity 5: Light Has Fingerprint?

We have seen that when light strikes an object, some of the light is absorbed by the object and some of the light is reflected off of the object. By sorting the different parts of light that are reflected off an object, scientists are able to uncover the chemical composition of the object. The drawing below shows what the sorted light looks like. This type of picture is called a line spectra. Each line represents a different part of the light given off by the object. Together the lines make up a signature (like a finger print) that identifies the specific chemical composition of the observed object.

diagram of line spectrum

A. Take a moment and study the different line spectra provided in the Spectral Catalog. In the blank box below, sketch the line spectra that a satellite would detect if it were pointed at a freshwater lake. Explain the reasoning behind your choice.


space for sketch of spectrum


Images of an object taken using remote sensing devices often use different colors to represent specific information about an observed object. You may have seen an example of this when looking at a map or picture of Earth. Often mountain regions are shown in brown while lowlands and valleys are shown in green. These colors do not represent the actual color of the region but rather have been altered to illustrate the elevation of the different areas. An image that has had colors added to it to represent specific features, like elevation or temperature or chemical composition, is called a false color image.

Examine the following false color image:


false color image os area of Yellowstone

This false color picture was taken of the area around a geyser at Yellowstone National Park. The satellite that took the picture used an instrument called a spectrometer to measure the spectra of different chemicals and minerals in the surface around the geyser. The colors shown are not the actual colors of the surface but rather have been used to identify where different types of minerals are present in the surface. In this image the reddish colored regions contain high concentrations of the mineral hematite. The blue colored areas contain high concentrations of the mineral calcium carbonate. The white areas are composed of primarily water and steam.

B. Sketch the different line spectra that would have allowed scientists to make this false color image. With each spectrum that you draw provide a label of the corresponding chemical or mineral.


space to sketch spectrum



space to sketch spectrum


space to sketch spectrum

C. Which colored regions of this image do you think correspond most directly to the location of the geyser? Explain your reasoning.

 

 

 

On Earth there are specific conditions and indicators that are used by scientists to identify the presence of life. For instance, life as we know it requires liquid water, and the majority of liquid water here on Earth is found between the temperatures of 0 - 100o Celsius. Therefore, in our search for life in the Solar System, we might look for signs that indicate that liquid water is present or has been in the past. Scientists have also identified chemical signatures for the presence of life. For instance, we might look for oxygen (O2), carbon dioxide (CO2), or methane (CH4) that has been given off by living organisms.

Examine the following false color picture:


infrared image of Yellowstone


This black and white image was taken of the same region of Yellowstone National Park now using an infrared camera. Again, the bright white areas signify higher temperatures (100oC and above) and the darker areas represent cooler temperatures (near 0oC).

D. Describe where you would look to water (above 70oC). Explain your reasoning.

 

 

 

Examine the following false color image:


false color image of Yellowstone

This false color image was taken of another region of Yellowstone National Park. Again, a spectrometer was used to measure the spectra of different chemicals and minerals.

The turquoise areas correspond to the spectrum shown below.

line spectrum



The yellowish-orange colored areas correspond to the spectrum shown below.

line spectrum



The pinkish-purple colored areas correspond to the spectrum shown below.

line spectrum


E. Label each spectrum with the name of the corresponding chemical or mineral. Then identify a process or organism that could have produced this chemical or mineral.

F. Imagine that the images from questions B, D and E were remote sensing images taken by a satellite of a distant planet. Describe how each of the images could be used to support the hypothesis that there is life on the distant planet.