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The largest unit for expressing distances across space at that time was the astronomical unit, equal to the radius of the Earth's orbit at 150 million kilometres (93 million miles). In those terms, trigonometric calculations based on 61 Cygni's parallax of 0.314 arcseconds, showed the distance to the star to be 660 000 astronomical units (9.9 ...
On land, the league is most commonly defined as three miles (4.83 km), although the length of a mile could vary from place to place as well as depending on the era. At sea, a league is three nmi (3.452 mi; 5.556 km). English usage also included many of the other leagues mentioned below (for example, in discussing the Treaty of Tordesillas).
Comparison of the ephemeris positions with time measurements expressed in Barycentric Dynamical Time (TDB) leads to a value for the speed of light in astronomical units per day (of 86 400 s). By 2009, the IAU had updated its standard measures to reflect improvements, and calculated the speed of light at 173.144 632 6847 (69) au/d (TDB).
Five summer hours is therefore not exact, but could indicate a time of approximately six modern hours.) They then progressed to the "faster step" or "full pace" [3] and were required to complete 24 Roman miles (35.544 km or 22.086 modern miles) in five summer hours loaded with 20.5 kilograms (45 lb). Training also included some forced marches ...
The radar mile is a unit of time (in the same way that the light year is a unit of distance), equal to the time required for a radar pulse to travel a distance of two miles (one mile each way). Thus, the radar statute mile is 10.8 μs and the radar nautical mile is 12.4 μs.
The most common distances are 50 kilometres (31.07 mi), 50 miles (80.47 km), 100 kilometres (62.14 mi), 100 miles (160.93 km), and continue up to the longest certified race distance of 3100 miles. [1] Timed events range from 6, 12, and 24 hours to 3, 6, and 10 days (known as Multiday races). Timed events are generally run on a track or a short ...
A light-year is the distance light travels in one Julian year, around 9461 billion kilometres, 5879 billion miles, or 0.3066 parsecs. In round figures, a light year is nearly 10 trillion kilometres or nearly 6 trillion miles. Proxima Centauri, the closest star to Earth after the Sun, is around 4.2 light-years away. [90]
The result was a measured radius of 696,342 ± 65 kilometres (432,687 ± 40 miles). [4] Haberreiter, Schmutz & Kosovichev (2008) [1] determined the radius corresponding to the solar photosphere to be 695,660 ± 140 kilometres (432,263 ± 87 miles). This new value is consistent with helioseismic estimates; the same study showed that previous ...