Venus or Mercury, depending in the type of "day" that you mean.
A "day" on Venus is -243.0185 Earth days long. The "minus" means it rotates in a direction opposite the Earth and all the other planets (except Uranus).
This "day " is the rotation period, called the "sidereal day".
However there's also the "solar day". That's roughly "sunrise to sunrise".
The solar day depends on a planet's orbital motion, as well as its rotation.
Venus has a solar day of about 116.5 Earth days.
For the solar day it's Mercury that has the longest day, because of
the direction of rotation of Venus. Mercury has a solar day of about 176 Earth days.
Comment: The "related link" given below isn't really related. It about the movie
called "The Longest Day".
Pluto has the longest year, if it was still a planet that is, equal to 248.76 Earth years. Since Pluto is no longer considered a planet, the planet with the longest year is Neptune, at 164.8 Earth years per revolution around the Sun.
Mars takes the longest of the inner planets.
Neptune has the longest orbital period, which is equal to 59,800 Earth days. Pluto's is even longer (90,588 Earth days), but it has since been reclassified as a dwarf planet.
Venus takes the second longest time to orbit the sun, with an orbital period of about 225 Earth days.
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.
Mercury. (It is NOT Venus).
No planet in our solar system has days longer than one Earth year. Venus has the longest day -- it's 243 Earth days.
Pluto has the longest year, if it was still a planet that is, equal to 248.76 Earth years. Since Pluto is no longer considered a planet, the planet with the longest year is Neptune, at 164.8 Earth years per revolution around the Sun.
There is no such planet known. The planet with the longest rotation period is Venus. That rotates in about 243 Earth days.
You would have to find the planet with the longest year and that would be your answer because as you knoe Earths year is 365 (about) days and Mercurys is 88 days so....
Mars takes the longest of the inner planets.
None. Venus has the longest rotation period of 243 days, less than a year.
Neptune has the longest year( Pluto would be but it isn't a planet) Mercury has the shortest year(1 year=88 earth days)
Neptune has the longest orbital period, which is equal to 59,800 Earth days. Pluto's is even longer (90,588 Earth days), but it has since been reclassified as a dwarf planet.
As Pluto is no longer considered a planet, the planet with the longest orbital period is Neptune. The Neptunian year is approximately 60,190 Earth days.
There are no planets in our solar system with a rotational period of 318 days. The longest is Venus, with a rotational period of 243 days.
The planet with the largest (or longest) rotation period is Venus, at 243 Earth days (retrograde, meaning clockwise, instead of counterclockwise like the Earth).