No, not all planets complete one orbit around the Sun in a year. The time it takes for a planet to orbit the Sun is determined by its distance from the Sun and is governed by Kepler's laws of planetary motion. The closer a planet is to the Sun, the shorter its orbital period.

Here are the orbital periods of the planets in our solar system:

1. Mercury: Approximately 88 Earth days

2. Venus: Approximately 225 Earth days

3. Earth: Approximately 365.25 Earth days (1 year)

4. Mars: Approximately 687 Earth days

5. Jupiter: Approximately 12 Earth years

6. Saturn: Approximately 29 Earth years

7. Uranus: Approximately 84 Earth years

8. Neptune: Approximately 165 Earth years

As you can see, while Earth takes one year to complete one orbit around the Sun, other planets have different orbital periods ranging from Mercury's 88 days to Neptune's 165 years.