Science Buddies: "Ask an Expert"

Hi! I need help with understanding the way skyglow is measured in this project for my conclusion. I completed the rest of the experiment (taking all the photos, calibration curve, finding the EET) and I'm trying to understand what is going on with Figure 4. Basically, I have the EETs and I can see that in some places the EET is up to 70x more than in the darkest place. So, for my conclusion, am I just measuring the skyglow relative from one place to another? Because I am not actually measuring definitive levels of skyglow in this experiment, right? I'm just confused as to how to word this in my conclusion and how it actually works...


[Administrator note: Project URL: https://www.sciencebuddies.org/science- ... re-skyglow ]

Hi there,

What Figure 4 is saying is that, for a given amount of pixels lit up in the sky glow photo, there is an equivalent calibration duration of time that exists. Essentially, the higher the value of the EET, the more pixels have been exposed, meaning the sky would likely have glowed more. Basically, you are making comparisons between sky glow amounts using a calibrated amount of sun, which is basically your control here, allowing you to make more precise comparisons between amounts of sky glow. In terms of relativity, you are measuring sky glow not relative to each other but really relative to the full sun calibration, which should make the amounts of sky glow more accurate when comparing multiple photos. You won't be able to definitively tell how much sky glow is actually in any given night photo, but you will be able to compare two from each other using the calibrated photo. Hope this helps.