Mars, because it takes the longest to get from opposition to opposition, when accounting for Earth's path around the Sun/
Neptune.
Technically, since Pluto is no longer a planet, but a dwarf planet, Uranus is the planet that takes the longest to orbit the sun.
Neptune is the furthest planet from the sun, taking the longest time to complete one orbit, 164.79 years in total.
A planet's sidereal year is the time it takes to complete one full orbit around the Sun relative to fixed stars, while its synodic year is the time it takes for the planet to return to the same position in relation to the Earth and the Sun. The synodic year is generally longer than the sidereal year due to the relative motion of Earth and the planet in their orbits. For example, Earth's sidereal year is about 365.25 days, while its synodic year (the time from one vernal equinox to the next) is also about 365.24 days, but for planets like Mars, the difference is more pronounced. This difference affects how we observe and measure planetary positions from Earth.
The synodic period of Mars is approximately 780 days, which is the time it takes for Mars to return to the same position relative to Earth and the Sun as observed from Earth. This period is influenced by both Mars' orbital period and Earth's orbital period around the Sun. Mars takes about 687 Earth days to complete one orbit around the Sun, while Earth takes about 365 days, leading to the longer synodic period. As a result, Mars appears to undergo retrograde motion and other positional changes as both planets orbit the Sun.
Pluto has the longest REVOLUTION period Venus has the longest ROTATION period
The synodic period of the moon is 29.5 days.
The orbital period is the time it takes for an object to complete one orbit around another object, like a planet around a star. The synodic period is the time it takes for a given object to return to the same position in the sky relative to the Sun as seen from Earth, for example the time between two consecutive similar configurations of a planet as observed from Earth.
Neptune.
A planets day (solar day) is the time it takes to rotate once on its axis relative to the sun, the synodic period. A year on a planet is the time taken for the planet travel once around the sun.
It's because we are going round the Sun and so are all the planets. For that reason the time it takes for a planet to go round the ecliptic and arrive back at the same apparent position - called its synodic period - is longer than a year. Venus and Mars have the longest synodic period because their times to go round once are the closest to 365 days. They take 225 and 687 days to go round but the synodic periods are 584 and 780 days. On the other hand the far-out planets do not move much in a year. Neptune takes 165 years to go round so its synodic period is only a little over 365 days and is 367½ days.
Uranus has the longest day of any planet in the solar system, with a rotation period of about 17 hours and 14 minutes.
Yeah this is the Synodic Period... are you doing a crossword for a planet class right now... me too!
The sidereal period is the time it takes for a celestial body to complete one orbit relative to the fixed stars, while the synodic period is the time it takes for a celestial body to return to the same position relative to the Sun as seen from Earth. The relationship between the two periods is influenced by the relative motion of the Earth and the celestial body, and can vary depending on their orbits and positions.
If you mean revolution on it axis (spin/day length) rather than orbital period, then the answer is the planet Mercury, where time between sunrises is roughly 176 Earth days.
A sidereal year is measured based on the planet's position in space relative to the background stars. A synodic year is measured based on the planet's position relative to the star it rotates around (i.e. the sun) Here's an image that is pretty helpful in visualizing.
Technically, since Pluto is no longer a planet, but a dwarf planet, Uranus is the planet that takes the longest to orbit the sun.