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1 chain (ch) = 2.12639E-15 lightyear (ly). Chain (ch) is a unit of Length used in Standard system. Lightyear (ly) is a unit of Length used in Metric system.

Chain: A Unit of Length Used for Measuring Land

The chain is a unit of length that is equal to 66 feet or 22 yards or 4 rods or 100 links. It is part of the US customary and imperial measurement systems. It is used for measuring land, especially in surveying and mapping. The symbol for chain is ch. There are 10 chains in a furlong, and 80 chains in one statute mile. An acre is the area of 10 square chains. The unit is named after the chain, a measuring device that was invented by Edmund Gunter, a clergyman and mathematician, in the 17th century. The chain is also sometimes called a Gunter’s chain, a surveyor’s chain or a land chain. In this article, we will explore the definition, history, usage and conversion of the chain as a unit of length.

Definition of the Unit

The chain is a unit of length that is equal to 66 feet or 22 yards or 4 rods or 100 links. It is one of the base units in the US customary and imperial measurement systems, along with the foot, the yard and the mile. The chain is also a derived unit in the International System of Units (SI), which is the most widely used system of measurement in the world. The SI base unit of length is the meter, which is defined as the length of the path travelled by light in vacuum during a time interval of 1/299792458 seconds.

The definition of the chain has not changed since its introduction by Edmund Gunter in 1620, who based it on an earlier English unit called an acre’s breadth, which was equal to one-tenth of a furlong or one-eightieth of a mile. However, the definition of the foot, which is used to define the chain, has changed several times over time, as different standards and methods of measurement were adopted by various countries and regions. The current definition of the foot as 0.3048 meter was agreed upon by an international treaty in 1959.

History of the Unit

The origin of the chain as a unit of length can be traced back to 1620, when Edmund Gunter created a measuring device called a chain. The chain was 66 feet long and consisted of 100 metal links connected by three rings each. The links were made of thick wire with a loop at each end. The chain had brass handles at each end for holding and folding. Gunter chose this unit because it was convenient for his work on surveying and mapping land. He also named this unit after himself, as he wrote in his book: "I have taken as unit for these measurements one hundredth part [of a furlong], which I will call an Chain".

Gunter’s unit was soon adopted by other surveyors and mapmakers, who found it useful for measuring distances and areas on flat or gently sloping land. The chain was also used for laying out roads, railways and canals. The chain became part of the US customary and imperial measurement systems, which were based on earlier English units that were brought by British settlers to America. The chain was also used in some other countries influenced by British practice, such as Canada and India.

In 1785, when the United States Congress passed the Land Ordinance Act to survey and divide the public land west of the Appalachian Mountains into rectangular townships and sections, the use of the chain as a unit of measurement was mandated by law. The act also defined the chain as equal to four rods or poles or perches. The surveyors who carried out this work were known as "chain bearers" or "chain carriers", and they marked each mile along their survey lines with wooden posts called "milestones".

In 1959, when the United States, Canada, the United Kingdom and some other Commonwealth countries agreed to adopt a common definition of the foot as 0.3048 meter, based on the international yard that was defined as 0.9144 meter by an international treaty in 1959, the chain became exactly equal to 20.1168 meters.

Usage of the Unit

The chain is a unit of length that is used for measuring land, especially in surveying and mapping. The chain is also used for measuring distances on roads, railways and canals. The chain is still used in some rural areas and historical contexts in the United States, Canada and some other countries that follow the US customary or imperial measurement systems.

The chain is used for various purposes, such as:

• Measuring length, width and area of land parcels and properties.
• Measuring distances and dimensions on maps and plans.
• Measuring boundaries and borders between states, counties and townships.
• Measuring road widths and lengths.
• Measuring railway track gauges and lengths.
• Measuring canal widths and depths.

How to Convert

The chain can be converted to other units of length by using conversion factors or formulas. Here are some examples of how to convert chains to other units of length in the US customary system, the imperial system and the SI system:

• To convert chains to feet, multiply by 66. For example, 10 ch = 10 × 66 = 660 ft.
• To convert chains to yards, multiply by 22. For example, 10 ch = 10 × 22 = 220 yd.
• To convert chains to miles, divide by 80. For example, 10 ch = 10 / 80 = 0.125 mi.
• To convert chains to centimeters, multiply by 2011.68. For example, one ch = one × 2011.68 = 2011.68 cm.
• To convert chains to meters, multiply by 20.1168. For example, one ch = one × 20.1168 = 20.1168 m.
• To convert chains to kilometers, divide by 49.7097. For example, 10 ch = 10 / 49.7097 = 0.2012 km.

Equivalents in Other Units and Scales

The chain can be expressed in terms of other units of length by using equivalent values or ratios. Here are some examples of how to express chains in other units of length:

• One chain is equal to four rods or poles or perches.
• One chain is equal to one-tenth of a furlong or one-eightieth of a mile.
• One chain is equal to one-hundredth of a league or one-fortieth of a league (US).
• One chain is equal to one-hundred-millionth of an astronomical unit or one-forty-billionth of a light-year.
• One chain is equal to one-thousandth of a nautical mile or one-three-thousand-six-hundredth of a degree of latitude or longitude.

Lightyear: A Unit of Length

The lightyear is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (9.46 × 10^¹² km), or 5.88 trillion miles (5.88 × 10^¹² mi). As defined by the International Astronomical Union (IAU), a lightyear is the distance that light travels in a vacuum in one Julian year (365.25 days). The lightyear is most often used when expressing distances to stars and other distances on a galactic scale, especially in non-specialist contexts and popular science publications.

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

Definition of the Lightyear

The lightyear is a unit of length that is equal to the product of the Julian year and the speed of light. The Julian year is a unit of time that is equal to 365.25 days or 31,557,600 seconds. The speed of light is a physical constant that is defined as 299,792,458 meters per second. The symbol for lightyear is ly.

The definition of the lightyear can be derived from the following formula:

1 ly = 1 Julian year × speed of light

1 ly = 31,557,600 s × 299,792,458 m/s

1 ly = 9,460,730,472,580,800 m

1 ly = 9.46 × 10^¹⁵ m

History of the Lightyear

The concept of the lightyear as a unit of distance was first proposed by the German astronomer Friedrich Wilhelm Bessel in 1838. He used it to estimate the distance to some nearby stars based on their parallax measurements. Parallax is the apparent shift in position of an object when viewed from different angles. Bessel calculated that the star 61 Cygni was about 10.3 lightyears away from Earth.

The term lightyear was popularized by the British astronomer James Bradley in his book Stellar Movements and the Structure of the Universe (1918). He used it to describe the distances to various stars and galaxies. He also introduced the term parsec as another unit of distance based on parallax.

The lightyear was officially recognized by the IAU in 1976 as part of its System of Astronomical Constants.

Usage of the Lightyear

The lightyear is a unit of length that is used for measuring astronomical distances that are too large to be expressed in other units such as kilometers or astronomical units (AU). An AU is equal to about 150 million kilometers or 93 million miles and is roughly the distance from Earth to the Sun.

The lightyear is commonly used in astronomy and cosmology to describe the distances to stars, galaxies, nebulae and other celestial objects. For example:

• The nearest star to Earth (other than the Sun) is Proxima Centauri, which is about 4.2 lightyears away.
• The center of our galaxy, the Milky Way, is about 27,000 lightyears away from Earth.
• The nearest large galaxy to ours, Andromeda, is about 2.5 million lightyears away.
• The farthest galaxy ever observed by humans, GN-z11, is about 13.4 billion lightyears away.

The lightyear can also be used to measure time intervals in cosmology by relating them to distances traveled by light. For example:

• The age of the universe is estimated to be about 13.8 billion years or about 13.8 billion lightyears.
• The cosmic microwave background radiation (CMB) is a remnant of the early universe that we can observe today. It was emitted when the universe was about 380,000 years old or about 46 billion lightyears away from us.
• The observable universe is a sphere around us that contains all the objects that we can see with our current technology. It has a radius of about 46 billion lightyears.

Example Conversions of Lightyear to Other Units

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

• To convert a lightyear to kilometers, multiply by 9.46 × 10^¹²:

1 ly × 9.46 × 10^¹² = 9.46 × 10^¹² km

• To convert a lightyear to miles, multiply by 5.88 × 10^¹²:

1 ly × 5.88 × 10^¹² = 5.88 × 10^¹² mi

• To convert a lightyear to AU, multiply by 63,241:

1 ly × 63,241 = 63,241 AU

• To convert a lightyear to parsecs, divide by 3.26:

1 ly / 3.26 = 0.31 pc

• To convert a kilometer to lightyears, divide by 9.46 × 10^¹²:

1 km / 9.46 × 10^12 = 1.06 × 10^^-13 ly

• To convert a mile to lightyears, divide by 5.88 × 10^¹²:

1 mi / 5.88 × 10^12 = 1.70 × 10^^-13 ly

• To convert an AU to lightyears, divide by 63,241:

1 AU / 63,241 = 1.58 × 10^^-5 ly

• To convert a parsec to lightyears, multiply by 3.26:

1 pc × 3.26 = 3.26 ly