Halley's Comet 1986

This famous comet has historically been spectacular. This diagram shows why the comet failed to show its stuff during the 1986 passage. You can see that the sun is between the earth and the comet was closets to the sun. It was at this point the comet 's tail was at a maximum. But all of this was "behind the sun" yielding viewing at a minimum from earth.

Earth's orbit is green. Mercury's orbit is orange . Halley's comet is white. Sun is yellow.