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Light Year (ly) - Unit Information & Conversion

Symbol:ly
Plural:light years
Category:Length

What is a Light Year?

Definition

A light-year is a unit of astronomical distance equal to the distance that light travels in one Julian year in a vacuum (approximately 9.461 trillion kilometers or 5.879 trillion miles).

History

The concept was first used by Friedrich Bessel in 1838 when measuring the distance to the star 61 Cygni.

Common Uses

  • Measuring distances to stars and galaxies
  • Expressing the vast scale of the universe in astronomy

Unit FAQs

Is a light-year a unit of time or distance?

A light-year (ly) is a unit of distance, not time. It represents the distance light travels in one year.

How far is a light-year in kilometers and miles?

One light-year is approximately 9.461 trillion kilometers (9.461 x 10^12 km) or 5.879 trillion miles (5.879 x 10^12 mi).

What is the closest star to Earth in light-years?

Excluding the Sun, the closest star system to Earth is Alpha Centauri, which is about 4.37 light-years away.

Light Year Conversion Formulas

To Meter:

1 ly = 9461000000000000 m
Example: 5 light years = 47305000000000000 meters

To Kilometer:

1 ly = 9461000000000 km
Example: 5 light years = 47305000000000 kilometers

To Hectometer:

1 ly = 94610000000000 hm
Example: 5 light years = 473050000000000 hectometers

To Decimeter:

1 ly = 94610000000000000 dm
Example: 5 light years = 473050000000000000 decimeters

To Centimeter:

1 ly = 946100000000000000 cm
Example: 5 light years = 4730500000000000000 centimeters

To Millimeter:

1 ly = 9461000000000000000 mm
Example: 5 light years = 47305000000000000000 millimeters

To Inch:

1 ly = 372480314960629950 in
Example: 5 light years = 1862401574803149600 inches

To Foot:

1 ly = 31040026246719160 ft
Example: 5 light years = 155200131233595800 feet

To Yard:

1 ly = 10346675415573054 yd
Example: 5 light years = 51733377077865260 yards

To Mile:

1 ly = 5878792849757.416 mi
Example: 5 light years = 29393964248787.082 miles

To Nautical Mile:

1 ly = 5108531317494.601 NM
Example: 5 light years = 25542656587473.004 nautical miles

To Micrometer:

1 ly = 9.461e+21 μm
Example: 5 light years = 4.7305e+22 micrometers

To Nanometer:

1 ly = 9.461e+24 nm
Example: 5 light years = 4.7305e+25 nanometers

To Astronomical Unit:

1 ly = 63241.97861 AU
Example: 5 light years = 316209.893048 astronomical units

To Parsec:

1 ly = 0.306608 pc
Example: 5 light years = 1.53304 parsecs

To Angstrom:

1 ly = 9.461e+25 Å
Example: 5 light years = 4.7305e+26 angstroms

To Point (Typography):

1 ly = 26818565783580610000 pt
Example: 5 light years = 134092828917903050000 points

To Mil/Thou:

1 ly = 372480314960629900000 mil
Example: 5 light years = 1.8624015748031494e+21 mils

To Fathom:

1 ly = 5173337707786527 fath
Example: 5 light years = 25866688538932630 fathoms

To Furlong:

1 ly = 47030342798059.33 fur
Example: 5 light years = 235151713990296.66 furlongs

To Link (Gunter's):

1 ly = 47030342798059330 li
Example: 5 light years = 235151713990296640 links

To Pace:

1 ly = 12416010498687664 pace
Example: 5 light years = 62080052493438320 paces

To Span:

1 ly = 41386701662292216 span
Example: 5 light years = 206933508311461060 spans

To Digit:

1 ly = 496640419947506560 digit
Example: 5 light years = 2483202099737533000 digits

To Cable Length:

1 ly = 51085313174946.01 cb
Example: 5 light years = 255426565874730.03 cable lengths

To Ell:

1 ly = 8277340332458443 ell
Example: 5 light years = 41386701662292216 ells

To Finger:

1 ly = 82773403324584430 finger
Example: 5 light years = 413867016622922100 fingers

To Roman Mile:

1 ly = 6392567567567.567 m.p.
Example: 5 light years = 31962837837837.836 Roman miles

To Stadion:

1 ly = 51140540540540.54 stadion
Example: 5 light years = 255702702702702.7 stadia

To Chi (Chinese):

1 ly = 28385838583858388 chi
Example: 5 light years = 141929192919291940 chi

To Shaku (Japanese):

1 ly = 31224422442244224 shaku
Example: 5 light years = 156122112211221120 shaku

To Li (Chinese):

1 ly = 18922000000000 li
Example: 5 light years = 94610000000000 li

To Toise:

1 ly = 4854284248332478 toise
Example: 5 light years = 24271421241662390 toise

To Bolt:

1 ly = 310400262467191.6 bolt
Example: 5 light years = 1552001312335958 bolts

To Rope:

1 ly = 1552001312335958 rope
Example: 5 light years = 7760006561679790 ropes

To Smoot:

1 ly = 5559407685979551 smoot
Example: 5 light years = 27797038429897756 smoots

To Sajene:

1 ly = 4434289463817023 sajene
Example: 5 light years = 22171447319085116 sajenes

To Ken:

1 ly = 5204070407040704 ken
Example: 5 light years = 26020352035203520 ken

To Wa:

1 ly = 4730500000000000 wa
Example: 5 light years = 23652500000000000 wa

To Vara:

1 ly = 11287282271534240 vara
Example: 5 light years = 56436411357671200 varas

To Aln:

1 ly = 15927609427609428 aln
Example: 5 light years = 79638047138047140 alnar

To Cubit (Royal/Egyptian):

1 ly = 18089866156787764 cubit
Example: 5 light years = 90449330783938820 cubits

To Versta:

1 ly = 8868578927634.047 versta
Example: 5 light years = 44342894638170.234 versts

To Arpent:

1 ly = 161806707598638.66 arpent
Example: 5 light years = 809033537993193.2 arpents

To Ri (Japanese):

1 ly = 2409218232747.6445 ri
Example: 5 light years = 12046091163738.223 ri

To Klafter:

1 ly = 4988663327181650 klafter
Example: 5 light years = 24943316635908252 klafter

To Yojana:

1 ly = 700814814814.8148 yojana
Example: 5 light years = 3504074074074.074 yojanas

To Skein:

1 ly = 86222295129775.45 skein
Example: 5 light years = 431111475648877.25 skeins

Convert Light Year

Need to convert Light Year to other length units? Use our conversion tool.

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Light Year Quick Info

ly
Symbol:ly
Category:Length
System:Various
Convert Light Year

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