To find the unit rate in revolutions per day, we can start by calculating the number of revolutions the planet makes in one day.
Since the planet spins 2 revolutions every 2 days, we divide the number of revolutions by the number of days:
\[ \text{Unit Rate} = \frac{2 \text{ revolutions}}{2 \text{ days}} = 1 \text{ revolution per day} \]
Thus, the unit rate is:
1