Note: use a mouse instead of a trackpad or touchscreen to limit frustration while using Afterglow. 

Click “Next” above to see the step-by-step instructions.

Alternate Format: Video Instructions

• Follow along with this tutorial video

Alternate Format: Written Instructions

1. You will use archival data for this. If you have your own Venus image you will also use that one.
   • Open each image in Afterglow using the “Open Files” icon in the upper left.
     • File path: Sample/Astro 101 Lab/Lab 3 – Galilean Revolution/Venus/[filename].fits
2. Measure the the illuminated angular distance  and the angular diameter on each Venus image.
   • Open each image and set the display to “Bright Target.”
   • Open the plotter tab
   • For each image take two measurements, and record them in the Skynet 3 Observation Report.
     • Illuminated Angular Distance
     • Angular Diameter
     • 
     • Illuminated angular distances will always be smaller than angular diameters.
   • For each image, calculate the phase:
     • The phase is the illuminated angular distance divided by the angular diameter. It will be between 0 and 1.
     •