The Center is the position of the Sun.
The picture shows from the galactic plane:
Back to Our Galaxy and the movement of planet Mercury
Answer question 3
- V = Direction of movement of the Milky way (towards Vega)
- GNP = Direction of Galactic North Pole
- GC = Direction of Galactic Centre
- CMB = Direction of movement relative to the Cosmic Microwave Background Radiation
- C = Galactic Centre.