22 SKYNEWS•NOVEMBER/DECEMBER 2019
LITTLE BLACK DOT ON THE SUN TODAY
for an image scale great enough to show
mercury well, use a telescope with an effective
focal length of at least 800mm. you may need to
add a barlow lens or a teleconverter to ensure
that the Sun’s disc ills the frame. the image above
was captured with a 5-inch f/6 refractor and a
canon eoS 60da camera, which features an apS-c
size “cropped frame” sensor. as with the most
recent mercury transit, in may 2016, only the sec-
ond half of the 2019 event is visible from western
canada. the composite photo at right, made up
of exposures shot at seven-minute intervals,
records the last four hours of the 2016 transit.
PHOTOS BY ALAN DYER