What speed should a galaxy move with respect to us so that the sodium line at `589.0 nm` is observed at `589.6 nm` ?

Explanation

To find the speed at which a galaxy should move with respect to us so that the sodium line at 589.0 nm is observed at 589.6 nm, we can follow these steps:

### Step 1: Identify the given values
- The original wavelength of sodium light, \(\lambda_0 = 589.0 \, \text{nm}\)
- The observed wavelength, \(\lambda = 589.6 \, \text{nm}\)

### Step 2: Calculate the change in wavelength
The change in wavelength (\(\Delta \lambda\)) can be calculated as:
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