When I was in high school, the physics teachers set up a telescope aimed at Venus as it crossed the Sun's radius. It wasn’t visible to the naked eye, but throug

When I was in high school, the physics teachers set up a telescope aimed at Venus as it crossed the Sun's radius. It wasn’t visible to the naked eye, but through the telescope, you could see Venus as a tiny black dot drifting across the field of view. It was fascinating to watch a planet move in a perfectly straight line along its orbit.