Today Mercury slid over the sun and I shot it with an additional infrared 850 nm filter. Mercury is at the bottom, a sunspot is visible on the Sun upper hemisphere.

Mercury passage over the Sun May 2016

A 70-200 VRII mounted on the 36 Mpx D800 gave a resolution of 2 pixels for Mercury passing over the Sun and 370 pixel for the Sun. Knowing the Sun is 1.64 times more distant than Mercury from Earth, the size ratio Sun / Mercury is 370*1.64/2 = 303.4 . Known the Sun diameter is 1.3914 million km, Mercury measures 4,586 km in diameter (the real value is 4,800 km).

Jupiter and the four Galilean moons

The same camera setting gives a resolution of 12 pixels for Jupiter, which is 6.8 times more distant from Earth than Mercury. Therefore the size ratio Jupiter / Mercury is 12*6.8/2 = 40.8 . Calculated that Mercury is 4586 km in diameter, Jupiter is 187,108 km (its real size is 143,000 km). More or less …