Today is January 16 __ only in the northern hemisphere only in the southern hemisphere in both the northern and southern hemisphere is a different month in the south from the north

The question is asking about the date January 16 in different hemispheres. The northern and southern hemispheres have different calendar systems due to the International Date Line. The International Date Line is an imaginary line of demarcation on the surface of Earth that runs from the North Pole to the South Pole and demarcates the change of one calendar day to the next. It is located at about 180 degrees longitude, except where it deviates to pass around some territories and island groups. This means that when it is January 16 in the northern hemisphere, it is January 17 in the southern hemisphere, and vice versa. Therefore, the correct answer is "in both the northern and southern hemisphere", as the date January 16 is recognized in both hemispheres, but it is considered a different day in each.