# Light-years to Micrometers (ly to μm)

Source: https://www.unitconvertercalculator.com/length/light-years-to-micrometers/

**1 ly = 9.4607304725808E+21 μm**

One light-year equals approximately 9.461 x 1021 micrometers (about 9.5 sextillion). The light-year measures interstellar distances; the micrometer measures cells and bacteria. About 22 orders of magnitude separate them.

## Formula

Convert Light-years to Micrometers

## Conversion Table

| Light-years (ly) | Micrometers (μm) |
|---|---|
| 1.0E-21 ly | 0 μm |
| 1.0E-20 ly | 94.607304725808 μm |
| 1.0E-19 ly | 946.07304725808 μm |
| 1.0E-18 ly | 9460.7304725808 μm |
| 1.0E-17 ly | 94607.304725808 μm |
| 1.0E-16 ly | 946073.04725808 μm |
| 1.0E-15 ly | 9460730.4725808 μm |
| 1.0E-14 ly | 94607304.725808 μm |
| 1.0E-13 ly | 946073047.25808 μm |
| 1.0E-12 ly | 9460730472.5808 μm |
| 1.0E-11 ly | 94607304725.808 μm |

## Units

### Light-year (ly)

The distance light travels in one Julian year (365.25 days) in vacuum. Exactly 9,460,730,472,580,800 meters. Used for interstellar distances.

### Micrometer (μm)

One millionth of a meter, also called a micron. Used in biology for cell sizes, in engineering for surface finishes, and in manufacturing tolerances.

## Background

A red blood cell (7 micrometers) is 7.4 x 10-22 light-years across. The nearest star is about 4.01 x 1022 micrometers away. Both numbers are incomprehensible, which tells you something about the extremes of physical scale.

## Good to Know

The micrometer reveals life. The light-year reveals the universe. Between them, 22 orders of magnitude span from the smallest living things to the gaps between the places where life might exist.

## FAQ

### How many micrometers are in 1 light-year?

One light-year contains approximately 9.461 x 1021 micrometers.

### How many light-years is 1 micrometer?

One micrometer equals approximately 1.057 x 10-22 light-years.

### Is this conversion ever used?

Never. Cells and stars occupy measurement domains 22 orders of magnitude apart.

## Non-Frequently Asked Questions

### How many bacteria span 1 light-year?

A bacterium is about 2 micrometers. One light-year (9.461 x 1021 um) fits about 4.7 x 1021 bacteria (4.7 sextillion). Earth has about 1030 bacteria total. You could line up all Earth's bacteria about 200 million times across 1 light-year. Bacteria are plentiful.

### How many red blood cells span the Milky Way?

The Milky Way is about 100,000 light-years across = 9.461 x 1026 micrometers. A red blood cell is 7 um. So about 1.35 x 1026 red blood cells across the galaxy. That is more blood cells than there are in all the humans who have ever lived. The galaxy is larger than all of humanity's blood.

### Is a virus closer in size to a person or to a light-year?

A virus (100 nm = 0.1 um) is about 1.8 x 107 times smaller than a person (1.8 m). A person is about 5.26 x 1015 times smaller than a light-year. So a virus is much closer to a person than a person is to a light-year. We are closer to viruses than to stars. Humbling.

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## See Also

- [Micrometers to Light-years](https://www.unitconvertercalculator.com/length/micrometers-to-light-years/)