How long are the days and years on the different planets of the Solar System?


Solar System
The further a planet’s orbit is from the Sun, the longer the year. What happens to days?
Laura Fazová Laura Fazová Weathered Chile 6 minutes

We must proceed from the assumption that not all days are the same. When we think of the day, we often associate it with the day/night cycle, marked by hours of light and dark; However, to define its duration on other planets, we will focus on the simple concept of “day”.

A day is basically the time it takes for a planet to complete one rotation around its axis: This is what scientists use to measure day length on nearby planets. On the other hand, the time it takes for a planet to reach a a complete revolution around the Sun is known as a year.

A sunny day and a starry day

One thing From an early age we are taught that an earthly day lasts about 24 hours: This interval is known as a solar day. However, the Earth’s orbit is elliptical, so solar days are variable: at latitudes far from the equator, some last a few minutes longer, others a few minutes less.

Interesting fact: Earth’s day was shorter in the past, but since the existence of the oceans and the moon, the rotation has slowed due to tidal friction.

That’s why it’s done difference from starry day, which is exactly the time it takes for the planet to rotate 360 ​​degrees. In the case of Earth, it takes exactly 23 hours and 56 minutes.

How does time pass on nearby planets?

Now that we know how days and years are measured on other planets, let’s take Earth’s duration as a reference to compare them. There are three planets in the solar system that have shorter days than Earth: Saturn (11 hours), Neptune (4 p.m.) e Uranium (5 p.m.). Planet with the longest day is Venus: it lasts 243 Earth days (5832 hours) to complete its rotation. Mars it is the one that is most similar in length to an Earth day, it is approx 25 hours.

As for years, their duration depends on the distance of the planet from our star: the further away a planet is, the longer it takes to complete its orbit, because the planet travels a greater distance and more slowly.


Mercury is the smallest rocky planet in the Solar System and the closest to the Sun. It is the planet that orbits our star the fastest. On the other hand, his rotation is very slowwhich makes for long days. They last 59 Earth days (1408 hours). However, a Mercury year is approximately 88 Earth days long.


Venus is the planet closest to us. It is the hottest planet in the Solar System. It belongs to the so-called stone planets and is very similar in size to Earth. It also represents a slow rotation around its axis and in a retrograde manner. This is the reason One day on Venus lasts 243 Earth days!

Mercury and Venus
From left to right you can see Mercury and Venus, which along with Earth and Mars are considered the inner planets because their orbits are closer to the Sun.


The red planet, despite its color, is not hot: it is the furthest from the Sun of the four rocky planets and the second closest to Earth. One year on Mars is equivalent to 687 Earth days or 1.88 Earth years. Furthermore, its rotation takes 24.6 hours, i.e. similar to the length of a day on Earth.


Jupiter is one of the gas giants: there could be as many as 11 terrestrial planets on its equator. It rotates rapidly, so its day is only 10 hours long, while its year can last up to 12 Earth years.


Saturn is another of the largest nearby planets, also considered a gas giant. Like Jupiter, it has days that are about 11 hours long. Its journey around the Sun ends every 29.4 Earth years.

Jupiter and Saturn
In the picture you can see Jupiter (left) and Saturn (right). Both planets are classified as gas giants along with Uranus and Neptune, although the latter are also considered ice giants due to their composition.


Uranus is one of the ice giants of our solar system because its composition is liquid “ice” of water, ammonia and methane. A year on Uranus can last a lifetime! It actually takes about 84 Earth years to complete a revolution around the Sun. Despite this, a day on this planet lasts only 17 hours.


Neptune is quite similar in composition to its neighbor Uranus, therefore also belong to the classification of ice giants. His day lasts 16 Earth hours and Its orbit around the Sun takes about 165 years.


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