How Old Are You... Really?
You think you're 10 years old. But on Mercury, you're 41. On Neptune, you're 0.06.
Your age depends on where you're standing.
Time works differently on every planet in our solar system. Some planets have days that last 6 months. Others spin so fast you'd see two sunrises before lunch. Discover how birthdays, days, and years work across the solar system.
🤯 Three Facts That Will Blow Your Mind
Two Birthdays Per Day
On Mercury, one day lasts 176 Earth days—but a year is only 88 Earth days. You'd celebrate your birthday twice before seeing one sunset!
Learn More About Mercury's Time →The Sun Rises in the West
Venus rotates backwards! The sun rises in the west and sets in the east. And one "morning" lasts 2 entire Earth months.
Discover Venus's Backwards Time →42 Years of Daylight
At Uranus's poles, the sun stays in the sky for 42 Earth years straight, then sets for another 42 years. One sunrise per lifetime!
Explore Uranus's Extreme Seasons →Time Isn't What You Think
We take time for granted. A day is 24 hours. A year is 365 days. Seasons change every 3 months. Simple, right?
But step off Earth, and everything changes:
Time is relative. Your age is relative. The rhythms of your life would be completely different on every world.
Ready to see for yourself?
Explore All 8 Planets
Each planet has its own unique relationship with time. Click on any planet to discover how days, years, and seasons work in that world.
Mercury
The Speed Demon
On Mercury, a year is shorter than a day. You'd have 2 birthdays during a single sunrise-to-sunrise!
Venus
The Backwards Planet
Venus rotates backwards! The sun rises in the west, and one "morning" lasts two entire Earth months.
Earth
The Goldilocks Planet
Earth is the only planet where days and years are balanced perfectly for complex life to evolve and thrive.
Mars
The Almost-Twin
A Mars day is only 40 minutes longer than Earth's - but you'll wait 6 months for summer to arrive!
Jupiter
The Speed Demon
Jupiter spins faster than any other planet in the solar system - a day lasts only 9 hours 56 minutes!
Saturn
The Patient Planet
Each season on Saturn lasts longer than most people's elementary school experience - 7+ Earth years!
Uranus
The Sideways Roller
If you lived at Uranus's pole, you'd see one sunrise per lifetime. The sun would spiral around the sky for 42 years, the...
Neptune
The Generational Planet
Neptune takes 165 Earth years to orbit the sun. It has only completed ONE orbit since its discovery in 1846!
Pluto
The Dwarf Planet (It's Complicated)
Pluto was a planet for 76 years (1930-2006) before being reclassified as a "dwarf planet." Kids born before 2006 learned...
Perfect for Learning
For Students
Calculate your age on every planet, explore interactive visualizations, and discover mind-blowing facts that'll make you see the solar system differently.
Start Exploring →For Teachers
Free lesson plans, printable worksheets, and curriculum-aligned resources to bring planetary science to life in your classroom.
Browse Resources →For Story Lovers
Immersive stories exploring what life would really be like experiencing time on different planets. Science meets storytelling.
Read Stories →For Space Enthusiasts
Deep-dive into the science of planetary rotation, orbital mechanics, and the bizarre realities of time across our solar system.
Explore the Science →Ready to Discover Your Cosmic Age?
Join thousands of people who have already discovered their ages across the solar system. Your perspective on time will never be the same.