Your age, across the cosmos
Discover Your Age Across The Solar System
Enter your birth date and see how old you are on every planet, what the Moon looked like the night you were born, your Pi and Phi ages, and how much you would weigh on other worlds.
Explore the tools
Four ways to see yourself in cosmic context.
The planets, at a glance
One year is one orbit around the Sun. Each world takes a different time to circle it.
Mercury races around the Sun in just 88 days, making it the fastest planet.
Venus rotates backwards and a day on Venus is longer than its year.
The only world we know of that hosts life — the pale blue dot.
Mars is home to Olympus Mons, the tallest volcano in the solar system.
Jupiter is so massive that all the other planets could fit inside it.
Saturn's rings span up to 282,000 km but are only about 10 meters thick.
Uranus rotates on its side, tilted at nearly 98 degrees.
Neptune has the strongest winds in the solar system, up to 2,100 km/h.
Frequently Asked Questions
Is my birth date stored anywhere?
No. All calculations run entirely in your browser. Your birth date never leaves your device.
Where does the planetary data come from?
Orbital periods, radii, and gravity values come from NASA fact sheets and the methods described in Jean Meeus, Astronomical Algorithms.
Is this astrology?
No. Cosmic Age Again uses real orbital mechanics and gravitational data. It has nothing to do with horoscopes or astrological signs.
What is a Pi Age?
A playful way to mark your life in multiples of π. One Pi year equals 3.14159 Earth years, so 10 Pi years is about 31.4 Earth years.