# The Doppler effect on light when space probes take pictures

When space probes like New Horizon's are traveling towards their target & they take photographs of their target en-route, does the incoming light need to be adjusted for the Doppler effect because of the speed of the probe?

• New Horizons travels at 16.26 km/s. the speed of light is 299792.46 km/s. I highly doubt that this would be an issue Jul 10, 2015 at 7:27
• @neelsg yeah, but it is the wavelength that is relevant. Indigo light starts at 380 nm, blue at 435 nm. Shift wavelength by 1 nm/s, that could be significant, if you are trying to use color to deduce composition. Jul 10, 2015 at 14:52
• Isn't this concept the basis of redshift? As long as the subject you're trying to photograph is illuminated with black body radiation with a known shift (or is emitting it), you should be able to determine how shifted the light is and compensate. Note: I say this as a layperson, so take it with a grain of salt..... Jul 10, 2015 at 16:51
• You can also use spectroscopy to detect redshift. Each molecule gives a known series of absorption lines. If that series is offset, you can work out the red/blueshift factor/speed. Jul 10, 2015 at 19:17

$$\lambda_r = \frac{\lambda c}{(c - v_r)}$$
The Helios probes reached a speed of $70km/s$ as they approached the sun. What effect would that have on them observing something with a wavelength of $600nm$?
$$\lambda_r = \frac{(600nm)(3.0\times 10^8 m/s)}{(3.0\times 10^8 m/s) - (7.0\times 10^4 m/s)}$$ $$\lambda_r = 600.14nm$$