How Time Shifts Across the Universe
Author: Erin - Little Star Shop
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Time In The Solar System
Here on Earth, time feels universal. We mark it by the steady ticking of a clock, the turning of a calendar, and the changing of the seasons. But the way we measure time is deeply local, shaped by the world around us, including Earth’s distance from the Sun and the speed of its orbit.
Leave the Earth, and the concept of a year begins to change. Across the Solar System and further out in the Universe, time is influenced by celestial motion, gravitational forces, and the extreme physics of deep space. While here on Earth, we measure our age by a single 365-day orbit around the Sun, that same one-year span means something radically different depending on where you stand in the cosmos. If we were based anywhere else in the solar system, or across the broader galaxy, our definition of a first birthday would be completely transformed.
In our Solar System, a year is simply the time it takes a planet to complete one full orbit around our star (the Sun). Because planets further from the Sun travel along larger orbits at slower speeds, the length of a year varies dramatically depending on the location. On Mercury, the innermost planet, it takes just 88 days to orbit the Sun. This means if you lived there, you would celebrate a birthday once every three months.
Venus moves slightly slower, completing an orbit in roughly 225 Earth days. Interestingly, Venus spins so slowly that one complete rotation on its axis takes longer than its journey around the Sun. A full Venus rotation lasts about 243 Earth days, while its year lasts roughly 225 days.
Beyond Earth, planetary time stretches further. Mars takes nearly two Earth years (687 days) to circle the Sun, meaning milestones happen at half the rate we are used to. Because a Martian year is nearly twice as long as an Earth year (687 days), someone who is 30 years old on Earth would be about 16 years old on Mars. Among the gas giants, planetary years become longer than entire human generations. Jupiter takes nearly 12 Earth years for a single orbit, meaning a child on Earth would start high school before celebrating their first birthday on Jupiter. Saturn takes nearly 30 Earth years to orbit the Sun, while Neptune takes an astonishing 165 Earth years. An entire human lifetime on Earth would span half of a single Neptunian orbit around the Sun.
Time On A Galactic Scale
Looking beyond our Solar System reveals timescales that are almost impossible to comprehend. Our entire Solar System orbits the centre of the Milky Way Galaxy at roughly 828,000 kilometres per hour. Despite this incredible speed, it still takes approximately 230 million Earth years to complete just one orbit of the Galaxy (often called the Galactic Year). By this measure, the entire history of human civilisation hasn't even lasted a fraction of a cosmic second. The last time Earth occupied this same space in the Galaxy, the dinosaurs were thriving on the planet. Earth has completed roughly 20 orbits of the Milky Way Galaxy since its formation 4.5 billion years ago.
Time Dilation
Time is not shaped by motion alone.
According to Einstein’s theory of general relativity, massive objects warp spacetime, causing time itself to bend and slow down under extreme conditions. This phenomenon is known as time dilation. It means that two people can experience different amounts of time depending on their speed or proximity to a strong gravitational field. For someone travelling close to the speed of light, or spending time near an extremely massive object, less time may pass for them than for someone far away and moving more slowly. Neither person would feel their own time slowing down, their clocks, thoughts, and biological processes would seem perfectly normal, but when they compared clocks, they would discover that they had aged by different amounts.
The stronger the gravitational field, the more slowly time passes relative to someone further away. Near super-dense objects like neutron stars or black holes, this effect becomes more dramatic. If you hovered near the edge of a black hole for just one hour, decades or even centuries would pass for everyone back home on Earth. In reality, surviving such an encounter would be another matter entirely. Read more about Black Holes here.
Time dilation also affects technology we use every day. GPS satellites carry extremely precise atomic clocks, and because they are moving quickly and orbiting higher above Earth’s gravitational field, their clocks tick at a slightly different rate from the clocks on the ground. These differences amount to only microseconds each day, but without corrections based on Einstein’s theories of relativity, GPS positions would quickly become inaccurate by several kilometres.
Even astronauts aboard the International Space Station experience a tiny difference in the passage of time. Because they travel around Earth at about 28,000 kilometres per hour, their motion causes their clocks to run slightly slower than clocks on Earth. The difference is incredibly small, only a few thousandths of a second over several months, but astronauts technically return to Earth fractionally younger than they would have been if they had stayed on the ground.
Speed also affects the passage of time. Under Einstein’s theory of special relativity, the faster you travel through space, the more slowly time passes for you compared with someone moving at a much lower speed.
If you boarded a rocket traveling at 90% of the speed of light, time inside your ship would run at about half the speed it does on Earth. Push that speed to 99.999% of light speed, and you could travel for just a few days while decades slip by on Earth.
Turning 1!
Little Star Shop has completed its very first trip around the Sun. One Earth year might be just a small blip on the cosmic scale, but to us, this first orbit has been something truly special.
We’re incredibly grateful to every customer, supporter, and fellow space lover who has joined our community along the way. Thank you for choosing us, believing in us, and helping make this first year so memorable.
Across the vastness of space and the immensity of time, it’s amazing to think that our paths crossed here to share this moment of time.
Here’s to many more Earth years of growing, discovering, dreaming, and exploring together.
Stay curious. ✨