Venus, Jupiter and the Moon

Here's an image of the recent Venus & Jupiter conjunction I shot with a 250mm lens. I then pasted in an image of the Moon taken previously to show their relative apparent sizes. At the time the shot was taken Jupiter was about 11 times further from Earth than Venus but being 11 times larger they appear as roughly the same size. Venus, on the left, appears as a crescent due to the angle of illumination by the Sun. Jupiter on the other hand always shows a full disc as it is outside our orbit. The only way to view Jupiter as a crescent is to go there, as the New Horizons probe did on the way to Jupiter.

Planetary imaging requires a seriously high level of magnification. If my maths is correct - something that can never be taken for granted - Jupiter is about as big as the tip of your finger from 200 feet away. The image below was taken with a 12" newtonian telescope fitted with a 4x barlow lens, giving an effective focal length of 6 metres. The mark to the left is the shadow of one of its moons, Io. The famous red spot was on the far side of the planet at the time it was taken.