Conversion Table

How to convert

1 lightyear (ly) = 9.46053E+16 decimeter (dm). Lightyear (ly) is a unit of Length used in Metric system. Decimeter (dm) is a unit of Length used in Metric system.

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

Decimeter: A Unit of Length Used in the Metric System

The decimeter (dm) is a unit of length in the metric system, which is the most widely used system of measurement in the world. The decimeter is equal to one tenth of a meter, which is the SI base unit of length. The decimeter is also a derived unit in the International System of Units (SI), which is the official system of measurement for science and engineering. The symbol for decimeter is dm. The decimeter is used for measuring medium distances and dimensions, such as the height of a bookshelf or the width of a door. The decimeter is also used for measuring volumes, such as the volume of a cube or a box. The decimeter is named after the deci prefix, which means one tenth in Latin. In this article, we will explore the definition, history, usage and conversion of the decimeter as a unit of length.

Definition of Decimeter

The decimeter is a unit of length that is equal to one tenth of a meter. It is defined as 1/10 meters. The meter 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 decimeter has not changed since its introduction by the French Academy of Sciences in 1795, as part of the decimal metric system that was adopted after the French Revolution. However, the definition of the meter has changed several times over time, as different standards and methods of measurement were developed by various countries and organizations. The current definition of the meter as based on the speed of light was agreed upon by an international treaty in 1983.

History of Decimeter

The origin of the decimeter as a unit of length can be traced back to 1795, when the French Academy of Sciences proposed a new system of measurement that was based on decimal fractions and natural constants. The system was called the metric system, and it was intended to replace the old and diverse systems of measurement that were used in France and other countries at that time. The metric system was designed to be simple, universal and rational.

The base unit of length in the metric system was the meter, which was defined as one ten-millionth of the distance from the equator to the North Pole along a meridian through Paris. The meter was divided into ten decimeters, each decimeter into ten centimeters, and each centimeter into ten millimeters. The prefixes deci, centi and milli indicated that they were one tenth, one hundredth and one thousandth of a meter respectively.

The metric system was officially adopted by France in 1799, and gradually spread to other countries over the next century. In 1875, an international treaty called the Metre Convention was signed by 17 countries to establish a common standard for measuring length and mass. The treaty also established an international organization called the International Bureau of Weights and Measures (BIPM) to maintain and improve the metric system.

In 1889, a new standard for the meter was created by using a platinum-iridium bar that was kept at BIPM. This bar was called the International Prototype Metre, and it was divided into ten equal parts to make standard decimeters. The bar was also compared with other national standards to ensure accuracy and consistency.

In 1960, an international conference called the General Conference on Weights and Measures (CGPM) adopted a new system of measurement called the International System of Units (SI), which was based on seven base units that could be derived from physical constants. The meter was redefined as 1,650,763.73 wavelengths of light emitted by a krypton-86 atom in a vacuum. The decimeter remained as a derived unit in SI, but it was no longer recommended for use in scientific and technical fields.

In 1983, another CGPM conference redefined the meter again as the length of the path travelled by light in vacuum during a time interval of 1/299792458 seconds. This definition was based on the speed of light, which is a universal constant that can be measured with high precision. The decimeter also changed accordingly to reflect this new definition.

Usage of Decimeter

The decimeter is a unit of length that is used for measuring medium distances and dimensions, such as the height of a bookshelf or the width of a door. The decimeter is also used for measuring volumes, such as the volume of a cube or a box.

The decimeter is commonly used in everyday life, especially in countries that follow the metric system. Some examples are:

• Measuring the dimensions of furniture and appliances.
• Measuring the size of books and magazines.
• Measuring the capacity of containers and bottles.
• Measuring the depth of water and soil.
• Measuring the distance between objects and landmarks.

The decimeter is also used in some scientific and technical fields, such as:

• Measuring the diameter and circumference of circles and cylinders.
• Measuring the volume and surface area of solids and liquids.
• Measuring the density and specific gravity of substances.
• Measuring the pressure and temperature of gases and fluids.
• Measuring the focal length and magnification of lenses and mirrors.

How to Convert Decimeter

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

• To convert decimeters to centimeters, multiply by 10. For example, 10 dm = 10 × 10 = 100 cm.
• To convert decimeters to meters, divide by 10. For example, 10 dm = 10 / 10 = 1 m.
• To convert decimeters to kilometers, divide by 10000. For example, 10 dm = 10 / 10000 = 0.001 km.
• To convert decimeters to inches, multiply by 3.937. For example, 10 dm = 10 × 3.937 = 39.37 in.
• To convert decimeters to feet, multiply by 0.328. For example, 10 dm = 10 × 0.328 = 3.28 ft.