Perihelion & Aphelion Sun

Two sets of images were carefully collected, one at perihelion on 2026 01 03 and the second on 2026 07 06 and processed before being composited into a final collage with lines to allow a visual comparison of apparent size.

After normalising the images to the same pixel scale, calculations were performed using the equatorial imaged diameters to calculate the ratio of the aphelion distance to the perihelion distances to confirm that, (a) Earth's orbit is elliptical and (b) the ratio of its semi-minor to semi-major axes; the result was in good agreement with scientifically established values for the current year with the error being less than 0.1%.

The telescope chosen for the task was the Skywatcher 200P. Being of Newtonian reflector construction it is free of chromatic aberration and it's focal length is invariant under the imaging conditions. Both being important considerations for accuracy.

See the image for further information.

Skywatcher 200P
Thousand Oaks type 2 Solar Filter
Nikon D800 (perihelion)
Nikon Z8 (aphelion)

PIPP & Autostakkert: process and stack sets of images from each date
GIMP: adjust levels, sharpen, compose composite add lines & text