sentences:  The visitor starts with the sun on the eastern summit of the Hill, and following the trail to the west from the Sun, in the direction of Mills Observatory, he or she will encounter another eight rocks representing the planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.Pluto is represented by the pier in the Mills Observatory, which supports the telescope there.The history of the observatory starts with John Mills (1806–1889), a manufacturer of linen and twine in the city of Dundee, and a keen amateur astronomer.