Why was the transit of venus historically so important to astronomers?

What was a major component of reaganomics? 1. the belief that tax cuts to the wealthy would trickle down to the less fortunate. 2.the belief that providing tax cuts to lower-socioeconomic americans would boost the economy. 3.the belief that boosting home ownership would lead to americans having an investment in the economy. 4.the belief that correcting the business cycle would boost output and reduce unemployment.