Final answer:
Tycho Brahe, often referred to as BJ, developed a geoheliocentric model to explain planetary motions without epicycles and helped establish a more accurate scale of the solar system.
Step-by-step explanation:
The theory referenced relates to BJ or Tycho Brahe's model of the universe. In the 16th century, Brahe proposed a geoheliocentric system, where the Earth sits at the center, the sun orbits the Earth, and other planets orbit the sun. This model was a significant step forward in astronomy because it explained the complex retrograde motions of the planets without resorting to the epicycles used in the Ptolemaic system. Moreover, it helped astronomers to work out a roughly correct scale for the solar system, paving the way for future discoveries in the field of astronomy.