1 For an observer on the ground with eye level at h = 5 ft 7 in (1.70 m), the horizon is at a distance of 2.9 miles (4.7 km). 2  For an observer standing on a hill or tower 100 feet (30 m) in height, the horizon is at a distance of 12.2 miles (19.6 km).
The mantle is a layer of the Earth between the crust and the core. The upper mantle starts below the crust and goes down to a depth of around 200 miles to the boundary with the lower mantle. The temperature of the mantle ranges from 900 degrees Fahrenheit near the crust to as high as 7000 degrees near the core.he Upper Mantle: Temperature and Depth. The upper mantle begins just beneath the crust and ends at the lower mantle. The thickness of the upper mantle is between 200 and 250 miles.
Beneath the Earthâs crust is the mantle, which is made up of a layer of gooey hot magma, semi-solid rocks and minerals. The mantle has a depth of about 1806 miles from the crust and reaches temperatures close to 1,832 degrees Fahrenheit. The core, the inner layer of the Earth, has the hottest temperature. It is divided into two sections: the outer core and the inner core. The outer core, the region surrounding the inner core, has a depth of 3,981 miles from the Earth's crust and is slightly cooler than the inner core, with temperatures close to 6,692 degrees Fahrenheit.