Added to this that a tunnel would have to be about 50 km long and that the removal of earth would require a fleet of trucks etc it is liable to detection.

Trimming lead times on sunspot detection would allow for better forecasts of space weather—bursts of radiation and charged particles from the sun that can cause real problems on and around Earth.

But as detection methods improved, astronomers began to find planets closer in size to Earth and planetary systems that contain nearly as many planets as our solar system.