If you moved to the Red Planet tomorrow, your birthday parties would become a lot more expensive. Why? Because they’d happen half as often. Honestly, when we talk about the length of a year on Mars, most people just think it’s "longer" than Earth’s. That’s true. But the reality is a bit more chaotic than just a few extra days on the calendar.
It takes Mars roughly 687 Earth days to orbit the Sun.
That is almost exactly 1.88 Earth years. Think about that for a second. If you’re 30 years old on Earth, you’re barely hitting your 16th birthday in Martian years. It changes your perspective on aging, doesn't it? But while the math seems simple on the surface, the way we actually measure time on Mars is where things get weird. NASA engineers and planetary scientists don't just use Earth days to track their rovers. They use something called "Sols."
Why the Length of a Year on Mars Messes With Our Heads
On Earth, we’re used to a nice, tidy 365-day cycle. Mars laughs at that. Because Mars is further away from the Sun than we are, it has a much larger path to travel. Physics 101 tells us that the further a planet is from its star, the slower it travels and the longer its "track" is.
Mars travels at an average speed of about 24 kilometers per second. Earth? We're zipping along at 30 kilometers per second. So, Mars is slower and has a longer commute.
The Sol vs. The Day
Here is where the confusion usually starts. A solar day on Mars—the time it takes for the Sun to return to the same spot in the sky—is called a Sol. A Sol is 24 hours, 39 minutes, and 35 seconds long. It’s just a tiny bit longer than an Earth day.
Because a Sol is longer, the number of "Martian days" in a Martian year isn't 687. It’s actually about 668 Sols.
If you were a colonist living in a habitat in Jezero Crater, your watch would have to tick slightly slower, or you'd just have to accept that "midnight" drifts by nearly 40 minutes every single day. NASA teams working on missions like Curiosity or Perseverance actually live on "Mars time." They wear special watches. They eat breakfast when it's 3:00 AM in California because it's sunrise at the rover's landing site. It's basically permanent jet lag.
The Elliptical Nightmare of Martian Seasons
Everything on Earth is relatively stable because our orbit is nearly a perfect circle. Mars is different. Its orbit is an ellipse—sort of an elongated egg shape.
This eccentricity means that Mars' distance from the sun changes drastically. At its closest point (perihelion), it’s about 206 million kilometers away. At its furthest (aphelion), it swings out to 249 million kilometers. This has a massive impact on the length of a year on Mars and specifically how the seasons play out.
- Spring in the Northern Hemisphere lasts about 194 Sols.
- Autumn is much shorter, clocking in at roughly 142 Sols.
It's lopsided. On Earth, our seasons are roughly equal in length. On Mars, the planet actually speeds up when it's closer to the sun, causing the seasons to vary wildly in duration. This isn't just a fun fact for astronomers; it's a life-or-death calculation for solar-powered machinery. If you’re a rover like the late Opportunity, a long, dark winter isn't just cold—it's a battery killer.
How We Actually Calculate the Martian Calendar
We don't really have a "standard" calendar for Mars like the Gregorian one we use here. However, scientists use something called "Mars Year 1."
They decided, somewhat arbitrarily, that Mars Year 1 started at the northern spring equinox of 1955. As I write this in 2026, we are currently in Mars Year 38. It feels a bit like sci-fi, but it’s the only way researchers can coordinate data across decades of observations.
The Tilt Factor
Mars has an axial tilt of about 25 degrees. That’s remarkably similar to Earth’s 23.5 degrees. Because of this, Mars experiences seasons just like we do. It has polar ice caps that grow and shrink. It has dust storms that kick up when the hemisphere tilts toward the sun.
But because the length of a year on Mars is so long, these seasons are grueling. A Martian winter lasts for months of Earth time. Imagine a winter that doesn't just last from December to March, but basically for an entire Earth year.
Atmospheric Pressure and the "Yearly" Cycle
The length of the year also dictates the planet's "breathing." Mars has an atmosphere that is 95% carbon dioxide. During those long, freezing winters at the poles, the temperature drops so low that the CO2 actually freezes out of the atmosphere and turns into solid dry ice.
This causes the atmospheric pressure of the entire planet to drop by about 25%.
When spring finally arrives (after nearly 200 days), that ice sublimates back into gas. The pressure spikes. This massive shift in pressure triggers the planet-wide dust storms that Mars is famous for. These aren't just little dust devils; they can shroud the entire planet in a brown haze for weeks, hiding the surface from telescopes on Earth.
Why Does This Matter for Humans?
If we ever want to build a city on Mars, we have to deal with the 687-day cycle. You can't just grow crops on a 365-day schedule. Your greenhouses would need to account for the fact that light intensity varies significantly as Mars moves along its elliptical path.
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Basically, the "year" is the heartbeat of the planet's climate.
Common Misconceptions About Martian Time
I hear people say all the time that a Mars year is exactly two Earth years. It’s close, but those missing 43 days matter. If you planned a mission based on a 2-year cycle, you'd miss the planet entirely.
Another big one? That Mars stays the same distance from Earth.
Because of the different lengths of our years, Earth and Mars have a "close encounter" only once every 26 months. This is called opposition. It’s the only time it makes sense to launch rockets. If you miss that window because you miscalculated the Martian year, you’re stuck waiting another two years for the planets to align again.
Essential Takeaways for Future Martians
Understanding the length of a year on Mars is basically about accepting that Earth’s rules don't apply. Here is the reality of living on a 687-day clock:
- Age Gaps: You'll need to divide your Earth age by 1.88 to get your "true" Martian age. It’s great for mid-life crises.
- Launch Windows: Space agencies only look at the calendar every 2.1 Earth years to send supplies or people.
- Sol Logic: You’ll gain 40 minutes of sleep every day, which sounds great until you realize your internal circadian rhythm is permanently confused.
- Extreme Seasons: Be prepared for seasons that last roughly double what you're used to, with unpredictable weather driven by CO2 cycles.
The next time you look at the night sky and see that little red dot, remember that time is moving differently over there. It’s slower, colder, and dictated by a massive orbital oval that makes our 365-day circle look like a toy.
To keep track of Martian time yourself, you can follow the Mars24 Sunclock developed by NASA’s Goddard Institute for Space Studies. It provides the current Sol and mission time for various rovers. If you’re planning on tracking Martian seasons, start by identifying the current "Mars Year" (currently MY 38) to see where the planet sits in its long journey around the sun.