Search results
Results From The WOW.Com Content Network
For radar (e.g. for wavelengths 300 to 3 mm i.e. frequencies between 1 and 100 GHz) the radius of the Earth may be multiplied by 4/3 to obtain an effective radius giving a factor of 4.12 in the metric formula i.e. the radar horizon will be 15% beyond the geometrical horizon or 7% beyond the visual. The 4/3 factor is not exact, as in the visual ...
Posidonius calculated the Earth's circumference by reference to the position of the star Canopus.As explained by Cleomedes, Posidonius observed Canopus on but never above the horizon at Rhodes, while at Alexandria he saw it ascend as far as 7 + 1 ⁄ 2 degrees above the horizon (the meridian arc between the latitude of the two locales is actually 5 degrees 14 minutes).
For example, the current distance to this horizon is about 16 billion light-years, meaning that a signal from an event happening at present can eventually reach the Earth if the event is less than 16 billion light-years away, but the signal will never reach the Earth if the event is further away. [9]
The ground-based long-distance observations cover the Earth's landscape and natural surface features (e.g. mountains, depressions, rock formations, vegetation), as well as manmade structures firmly associated with the Earth's surface (e.g. buildings, bridges, roads) that are located farther than the usual naked-eye distance from an observer.
While the Kármán line is defined for Earth only, several scientists have estimated the corresponding figures for Mars and Venus. Isidoro Martínez arrived at 80 km (50 miles) and 250 km (160 miles) high, respectively, [31] while Nicolas Bérend arrived at 113 km (70 miles) and 303 km (188 miles). [32]
While the typical distance between Earth and the moon is an ... greater thickness of Earth’s atmosphere near the horizon, ... closest of the year at 222,095 miles (357,428 kilometers) away.
Graphs of distances to the true horizon on Earth for a given height h. s is along the surface of Earth, d is the straight line distance, and ~d is the approximate straight line distance assuming h << the radius of Earth, 6371 km. In the SVG image, hover over a graph to highlight it.
They dug tunnels large enough for an electric railroad to connect to a supply base over 150 miles away. The 2-mile-long complex, powered by a nuclear reactor, was large enough for 200 soldiers.