Length & distance

Just how long is 1 light-day?

Solar neighbourhood

1 light-day

2.5902 × 10¹³ mmetres

8.4981 × 10¹³ ftfeet

1.6095 × 10¹⁰ mimiles

173.14 AUastronomical units

1 light-day173.1 AULength · definition

Neptune’s orbital distance30.11 AUDistance · rounded reference

Both marked spans share one linear scale. Artwork keeps its proportions; poses and surface detail are illustrative. A ruler represents the selected distance or unrolled circumference; it is not the physical size of the pictured body.

A little perspective

The length of 1 light-day is about 5.75 times the distance of Neptune’s orbital distance.

Measurements, assumptions & sources +

1 light-day

The quantity is exact as entered. Comparisons use the clearly stated specimen, model or nominal measurement.

NIST — SI conversion factors

Neptune’s orbital distance

A rounded 30.11 AU semi-major-axis reference, not today’s distance.

Defined examples — our methodology

The marked distance is calibrated. Unmeasured illustration details are representative.

Measurement details

Why these numbers?

The visual compares length with distance. The records below preserve each value’s basis and caveats.

1 light-day

173.1 AU

Length · definition

The quantity is exact as entered. Comparisons use the clearly stated specimen, model or nominal measurement.

Neptune’s orbital distance

30.11 AU

Distance · rounded reference

A rounded 30.11 AU semi-major-axis reference, not today’s distance.

Comparing: Length ↔ Distance
Relative size: 1 light-day is larger on this measurement by a factor of about 5.75. 1 light-day's selected measurement is approximately 475% greater than Neptune’s orbital distance's.