* Orion in December: You're correct, Orion appears in the eastern sky in December. This is because Earth's rotation and orbit cause the constellations to shift across the sky throughout the year.

* Orion in March: By March, Orion will have moved to the western sky.

Here's why:

* Earth's Orbit: The Earth revolves around the Sun, and as it does, our perspective of the night sky changes. Think of it like driving past a long row of trees. The trees you see first will appear in front of you, and then gradually shift to the side and eventually behind you as you continue driving.

* The Celestial Sphere: We imagine the stars on a giant sphere (the celestial sphere) that surrounds Earth. As the Earth orbits the Sun, our viewpoint of this sphere changes.

* Orion's Movement: Because of Earth's orbit, constellations like Orion appear to "drift" westward over time. This movement is subtle each night, but becomes noticeable over several months.

In summary: Orion's position in the sky changes due to Earth's orbit. If it's in the east in December, by March it will have moved to the west.