Astronomers on planet Xearth have made several remarkable discoveries. After inventing the telescope, they quickly discovered a new planet in their solar system, Xearth, that is very much like Earth. The planet Xearth orbits its star in a nearly circular path, with an average distance of 150 million kilometers (1 AU), a period of one Earth year, and a solar day that lasts 24 hours. But unlike Earth, there weren’t any other known planets in the solar system…until now. Moments after the sun set below the horizon, three astronomers on Xearth happened to focus their telescopes at the zenith of the evening sky, all seeing the same new planet. In their excitement, the astronomers race to publish their discoveries. The first astronomer claims that, by her calculations, the newly discovered planet orbits their sun with a radius of 50 million kilometers (0.33 AU). The second astronomer says that, by her calculations, the planet in fact orbits their sun with a radius of 300 million kilometers (2 AU). The third astronomer disagrees with the other two — by her calculations, the planet has a very similar orbit to Xearth, with a radius of 150 million kilometers (1 AU). Clearly only one of them is correct. Which astronomer should we believe? Justify your answer.