This particular meridian is the basis of the Eastern Australian Standard Time, used in Queensland, New South Wales (except Broken Hill), Victoria and Tasmania.
The 150 Degrees East Meridian crosses the Oxley Highway 34 kilometres south-west of Gunnedah. Methods of measuring time have varied over the ages, but the time unit most commonly employed has been the apparent daily circuit of the sun, from which solar time is derived.
The solar day is based on one complete rotation of the earth around its axis. Solar days are not uniform in length, because the movement of the earth is constant, modern time calculation is based on the average solar day.
Located west along the Oxley Highway, there is a rest area, information board, a sundial and barbecue facilities.