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1 league (league) = 1.80058E-13 parsec (pc). League (league) is a unit of Length used in Standard system. Parsec (pc) is a unit of Length used in Metric system.

League: A Unit of Length

The league is an old unit of length that was common in Europe and Latin America, but is no longer official in any nation. It was derived from an ancient Celtic unit and adopted by the Romans. It was the distance a person or a horse could walk in about one hour, usually about 3 to 5 kilometers. The league varied in length from 2.4 to 4.6 statute miles in different regions.

In this article, we will explore the definition, history, usage and conversion of the league as a unit of length.

Definition of the League

The league is a unit of length that is equal to 3 miles or 4.8 kilometers in the English-speaking countries. However, the word league often refers to the Spanish, Portuguese or French league, which have different values.

The Spanish league was originally defined as 5,000 varas (a Spanish yard), about 2.6 miles or 4.2 kilometers. The Portuguese league was also 5,000 varas, but the vara was slightly longer, making the league about 2.7 miles or 4.4 kilometers. The French league was based on the nautical mile and was equal to 3 nautical miles or 5.6 kilometers.

The league is not a standard unit and has no symbol.

History of the League

The origin of the league as a unit of length can be traced back to ancient times, when it was used as a measure of distance based on the human or animal pace. The word league comes from the Latin word leuga, which was derived from the Celtic word leuca. It referred to the distance that could be covered by a person or a horse in one hour.

The league was used by the Romans, who defined it as one and a half Roman miles (7,500 Roman feet or 2.2 kilometers). The Roman league was also called leuga Gallica (the Gaulish league) or leuga Germanica (the Germanic league), depending on the region.

The league was adopted by other countries that followed the Roman system of measurement, such as Spain, Portugal and France. It varied in length from country to country and from time to time, depending on local standards and methods of measurement.

The league was abolished by Philip II of Spain in 1568, but it continued to be used unofficially in some parts of Latin America. The league was also incorporated into the imperial system of measurement, which was established by an act of Parliament in 1824. The imperial system was based on seven base units that could be derived from natural and traditional units. The league remained as a derived unit in the imperial system, but it was no longer recommended for use in scientific and technical fields.

Usage of the League

The league is a unit of length that is used for measuring long distances and dimensions, such as the length of a road or the circumference of a lake.

The league is rarely used in modern times, except for historical or literary purposes. However, some countries still use it for some specific applications.

For example:

• In Argentina, a league is equal to 5 kilometers and is used for measuring land area.
• In Brazil, a league is equal to 6 kilometers and is used for measuring distances on roads and highways.
• In Mexico, a league is variable and depends on the terrain and the mode of transportation. It is used for measuring distances between towns and villages.
• In France, a league is equal to 4 kilometers and is used for measuring distances on maps and signs.
• In Spain, a league is equal to 4 kilometers and is used for measuring distances on roads and highways.

Example Conversions of League to Other Units

The league can be converted to other units of length by using different factors and formulas. Here are some examples of conversion for different types of leagues:

• To convert an English league to miles, multiply by 3:

1 English league x 3 = 3 miles

• To convert an English league to kilometers, multiply by 4.8:

1 English league x 4.8 = 4.8 kilometers

• To convert a Spanish league to miles, multiply by 2.6:

1 Spanish league x 2.6 = 2.6 miles

• To convert a Spanish league to kilometers, multiply by 4.2:

1 Spanish league x 4.2 = 4.2 kilometers

• To convert a Portuguese league to miles, multiply by 2.7:

1 Portuguese league x 2.7 = 2.7 miles

• To convert a Portuguese league to kilometers, multiply by 4.4:

1 Portuguese league x 4.4 = 4.4 kilometers

• To convert a French league to miles, multiply by 3.5:

1 French league x 3.5 = 3.5 miles

• To convert a French league to kilometers, multiply by 5.6:

1 French league x 5.6 = 5.6 kilometers

• To convert a mile to leagues, divide by the appropriate factor:

1 mile / 3 = 0.333 English leagues

1 mile / 2.6 = 0.385 Spanish leagues

1 mile / 2.7 = 0.370 Portuguese leagues

1 mile / 3.5 = 0.286 French leagues

• To convert a kilometer to leagues, divide by the appropriate factor:

1 kilometer / 4.8 = 0.208 English leagues

1 kilometer / 4.2 = 0.238 Spanish leagues

1 kilometer / 4.4 = 0.227 Portuguese leagues

1 kilometer / 5.6 = 0.179 French leagues

Parsec: A Unit of Length

A parsec is a unit of length that is often used in astronomy to measure the large distances to astronomical objects outside the Solar System. It is approximately equal to 3.26 light-years or 206,265 astronomical units (au), which are the average distances from the Earth to the Sun. One parsec is about 30.9 trillion kilometres or 19.2 trillion miles.

Definition of the parsec

The word parsec is a combination of “parallax” and “arcsecond”, which are terms related to the measurement of angles. Parallax is the apparent shift in position of an object when viewed from different perspectives. Arcsecond is a unit of angle that is equal to one sixtieth of an arcminute, or one three thousand six hundredth of a degree.

A parsec is defined as the distance at which one astronomical unit subtends an angle of one arcsecond. In other words, it is the distance from which the Earth-Sun distance would appear as one arcsecond on the sky. This can be illustrated by an imaginary right triangle, where the adjacent side is one au, the opposite side is one parsec, and the angle opposite to the parsec side is one arcsecond.

History of the parsec

The concept of the parsec was first proposed by the British astronomer Herbert Hall Turner in 1913, as a convenient unit for expressing stellar distances. He coined the term by blending “parallax” and “second”. He also suggested using the symbol “pc” for parsec.

The first measurement of a stellar parallax was made by Friedrich Bessel in 1838, for the star 61 Cygni. He found that the star had a parallax of 0.314 arcseconds, which corresponds to a distance of about 10.4 parsecs. Since then, many more stars have been measured for their parallaxes, using various methods such as telescopes, satellites and interferometers.

The parsec is now widely used in astronomy and astrophysics, especially for objects within and around the Milky Way galaxy. For more distant objects, such as galaxies and quasars, larger units such as kiloparsecs (kpc), megaparsecs (Mpc) and gigaparsecs (Gpc) are used.

How to convert parsec

To convert parsecs to other units of length, we can use the following conversion factors:

• 1 pc = 3.0857 × 10^¹⁶ m
• 1 pc = 1.9174 × 10^¹³ mi
• 1 pc = 2.06265 × 10^⁵ au
• 1 pc = 3.26156 ly

To convert other units of length to parsecs, we can use the inverse of these conversion factors:

• 1 m = 3.24078 × 10^^-17 pc
• 1 mi = 5.21553 × 10^^-14 pc
• 1 au = 4.84814 × 10^^-6 pc
• 1 ly = 0.306601 pc

Where parsec is used

The parsec is mainly used in astronomy and astrophysics, as it is a convenient unit for expressing distances between stars and other celestial objects. For example:

• The nearest star to the Sun, Proxima Centauri, is about 1.3 pc away.
• The center of our galaxy, the Milky Way, is about 8 kpc away.
• The nearest galaxy to ours, Andromeda, is about 780 kpc away.
• The most distant quasar known, ULAS J1342+0928, is about 8.8 Gpc away.

The parsec can also be used in other fields that deal with large distances or angles, such as geodesy, navigation and surveying.

Example conversions of parsec to other units

Here are some examples of converting parsecs to other units of length:

• How many meters are in one parsec?

To convert one parsec to meters, we multiply by the conversion factor:

1 pc × 3.0857 × 10^¹⁶ m/pc = 3.0857 × 10^¹⁶ m

• How many miles are in 10 parsecs?

To convert 10 parsecs to miles, we multiply by the conversion factor:

10 pc × 1.9174 × 10^¹³ mi/pc = 1.9174 × 10^¹⁴ mi

• How many astronomical units are in 0.01 parsecs?

To convert 0.01 parsecs to astronomical units, we multiply by the conversion factor:

0.01 pc × 2.06265 × 10^⁵ au/pc = 2.06265 × 10^³ au

• How many light-years are in 100 parsecs?

To convert 100 parsecs to light-years, we multiply by the conversion factor:

100 pc × 3.26156 ly/pc = 326.156 ly

• How many parsecs are in one meter?

To convert one meter to parsecs, we divide by the conversion factor:

1 m / (3.0857 × 10^¹⁶ m/pc) = 3.24078 × 10^^-17 pc

• How many parsecs are in one mile?

To convert one mile to parsecs, we divide by the conversion factor:

1 mi / (1.9174 × 10^¹³ mi/pc) = 5.21553 × 10^^-14 pc

• How many parsecs are in one astronomical unit?

To convert one astronomical unit to parsecs, we divide by the conversion factor:

1 au / (2.06265 × 10^⁵ au/pc) = 4.84814 × 10^^-6 pc

• How many parsecs are in one light-year?

To convert one light-year to parsecs, we divide by the conversion factor:

1 ly / (3.26156 ly/pc) = 0.306601 pc