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Calcimator

Light Travel Time

Calculate how long light takes to travel a given distance. Enter distance in AU or km and get travel time in seconds, minutes, hours, days, or years.

Inputs

Results

Light Travel Time

8.32 minutes

Time (seconds)

499.005 s

Time (minutes)8.317 min
Time (hours)0.139 hrs
Time (days)0.006 days
Time (years)0 yr
Distance (AU)1 AU
Distance (ly)0 ly
Distance (pc)0 pc
Distance Light Minutes8.32
Distance Light Hours0.14
How to Use This Calculator
  1. Choose the Distance Unit: AU for solar-system distances or km for specific spacecraft or planetary calculations.
  2. Enter the Distance value — 1 AU is Earth to Sun, 4.2 AU reaches Jupiter at closest approach.
  3. Read Light Travel Time in the most relevant unit: seconds for near-Earth objects, minutes for the inner solar system, years for stars.
  4. Use the Distance (ly) and Distance (pc) outputs to convert your solar-system measurement to stellar-scale units.
  5. Compare your result to the reference chart showing Moon, Sun, planets, and Pluto for quick sanity-checking.

What each input means

Distance
Distance value in the selected unit (AU or km)
Distance Unit
Choose whether the distance is in AU (1 AU = Earth-Sun distance) or kilometers

How this is calculated

Formula

t = d / c (c = 299,792.458 km/s; 1 AU = 149,597,870.7 km)

Worked example, using the default values

  1. Identify Input Parameters
    Distance = 1, Distance Unit = 1 = 2 input(s) provided
  2. Calculate Light Travel Time
    8.32 minutes = 8.32 minutes
  3. Calculate Time
    Time
    499.005 = 499.005
  4. Calculate Time
    Time
    8.317 = 8.317
  5. Calculate Time
    Time
    0.139 = 0.139

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