Many find it difficult to Simualte the Day and Night side of Earth in 3ds max, but its very simple that we could achieve it in a single map. In this 3d tutorial we are going to do that. The side of earth exposed to sunlight will show the real color map of earth, while the side in shadow will show the night time map of earth.

Step 1:

Create a sphere in one of the viewports and assign a standard material to it.

Step 2:

Then click on the maps rollout and go to the diffuse slot of the material that you assigned to the sphere.

Step 3:

Then click on the button labelled 'None'.

Step 4:

Then form the Material/Map Browser select Falloff Map.

Step 5:

Then under the Falloff Parameters select Shadow/Light as Falloff type.

Now can see two slots for maps, the black one is for shadow and the white is for Light. Now click on the button labelled None in the shadow slot and form the Material/Map Browser select Bitmap.

For the Bitmap part we are going to use two maps, one real color map and the other night map.

Real Color Map

Night Map

Dont worry this is just a sample, I have provided high resolution maps (4096 X 2048) with the download. Ok lets move on to the next step.

Step 6:

For the Shadow map assign the Night map of earth and for the Light Map assign the Real color Map of earth as shown below.

Step 7:

Then place an omni light in the scene and adjust the viewport such that you can see both the illuminated side as well as the side in the dark. (Ref Picture)
Step 8:

Then click Go To Parent button (Ref Pictures below) and click on the button labelled None in the Self illumination slot and form Material/Map Browser select Bitmap and assign the same Night Map that you assigned to the Shadow Map within Falloff.

Go To Parent highlighted in pink

Self Illumination slot with Night map assigned.

Now you render the viewport that you adjusted in Step 7. You should get the result as shown below. If you got it wrong dont worry, download the file provided and see how the maps are assigned. Render an animation clip and see how the map transits from real color to night map. Hope you like it.