Compass and scale image for Comet C/2013 A1 Siding Spring (3 epochs)

Compass and scale image for Comet C/2013 A1 Siding Spring (3 epochs)
Compass and scale image for Comet C/2013 A1 Siding Spring (3 epochs) <a href="http://hubblesite.org/">Hubblesite.org</a>