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Both calculators run independently — change the inputs on either side to compare results.
Astronomy
Light Travel Time Calculator
Find how long light takes to travel any astronomical distance. Useful for understanding how old the light from distant stars and galaxies is when it reaches Earth.
Fill in the required fields to see your result.
Astronomy
Redshift Velocity Calculator
Compute the recession velocity of a nearby galaxy from its redshift z using v = c·z, where c is the speed of light. Part of the Hubble-Lemaître law — the empirical relation that established the expanding universe.
Fill in the required fields to see your result.
Key differences
| Light Travel Time Calculator | Redshift Velocity Calculator | |
|---|---|---|
| Category | Astronomy | Astronomy |
| Inputs required | 1 | 1 |
| Result | Light Travel Time (years) | Recession Velocity (km/s) |
| What it does | Find how long light takes to travel any astronomical distance. Useful for understanding how old the light from distant stars and galaxies is when it reaches Earth. | Compute the recession velocity of a nearby galaxy from its redshift z using v = c·z, where c is the speed of light. Part of the Hubble-Lemaître law — the empirical relation that established the expanding universe. |