Beautiful Virgin Islands

Sunday, Jul 06, 2025

Here's why astronauts age slower than the rest of us here on Earth

Here's why astronauts age slower than the rest of us here on Earth

The next time you find yourself wishing the weekend would last longer, stay low to the ground and move really fast.

Time feels like one of the only constants in life — it passes day after day at the same pace.

Then Albert Einstein had to go and ruin that for us.

We've all heard the phrase that "time is relative," but it can be difficult to wrap the mind around what that actually means.

The phrase came from Einstein's Theory of Relativity that joined space and time and created the idea of a fabric that permeates the whole universe: "space-time."

We all measure our experience in space-time differently. That's because space-time isn't flat — it's curved, and it can be warped by matter and energy.

So depending on our position and speed, time can appear to move faster or slower to us relative to others in a different part of space-time. And for astronauts on the International Space Station, that means they get to age just a tiny bit slower than people on Earth. 

That's because of time-dilation effects. First, time appears to move slower near massive objects because the object's gravitational force bends space-time.



The phenomenon is called "gravitational time dilation." In a nutshell it just means time moves slower as gravity increases.

That's why time passes slower for objects closer to the center of the Earth where the gravity is stronger.

That doesn't mean you could spend your life in a basement, just to outlive the rest of us here on the surface. The effect isn't noticeable on such a small scale. If you became a basement hermit, then across your entire lifetime you'd only age a fraction of a second slower than everyone else above ground.

But this concept gets pretty crazy when you start thinking about it:

 *  A watch strapped to your ankle will eventually fall behind one strapped to your wrist.

*  Your head technically ages more quickly than your feet.

*  Time passes faster for people living on a mountain than those living at sea level.

Time gets even weirder though.

The second factor is something called "relative velocity time dilation" where time moves slower as you move faster.

The classic example of this is the twin scenario. One twin blasts off in a spaceship traveling close to the speed of light, and one twin stays behind on Earth. When the space-traveling twin returns to Earth, she's only aged a couple years, but she's shocked to find that her Earth-bound sister has aged over a decade.

Of course no one has performed that experiment in real life, but there's evidence that it's real. When scientists launched an atomic clock into orbit and back — while keeping an identical clock here on Earth — it returned running ever so slightly behind the Earth-bound clock.

Then time gets even more complicated because gravitational time dilation and relative velocity time dilation can happen at the same time. A good way to think about it is to consider the astronauts living on the International Space Station.

Currently, an international crew of seven live and work aboard the ISS, orbiting Earth about every 90 minutes, according to NASA.

They're floating about 260 miles above, where Earth's gravitational pull is weaker than it is at the surface. That means time should speed up for them relative to people on the ground. But the space station is also whizzing around Earth at about nearly five miles per second.

That means time should also slow down for the astronauts relative to people on the surface.

You'd think that might even out, but actually their velocity time dilation has a bigger effect than their gravitational time dilation, so astronauts end up aging slower than people on Earth.

The difference isn't noticeable though — after spending six months on the ISS, astronauts have aged about 0.005 seconds less than the rest of us.

That means that when former NASA astronaut Scott Kelly returned home in 2016 from his history-making, year-long stay on the ISS, he technically was 0.01 second younger than his twin astronaut brother — and now US senator — Mark Kelly who stayed on Earth.

So the next time you find yourself wishing the weekend would last longer, stay low to the ground and move really fast. It won't feel like your weekend got any longer, but technically you may gain a teeny, tiny fraction of a fraction of a second.

Remember, time is relative.

Newsletter

Related Articles

Beautiful Virgin Islands
0:00
0:00
Close
Elon Musk Founds a Party Following a Poll on X: "You Wanted It – You Got It!"
London Stock Exchange Faces Historic Low in Initial Public Offerings
A new online platform has emerged in the United Kingdom, specifically targeting Muslim men seeking virgin brides
Trump Celebrates Independence Day with B-2 Flyover and Signs Controversial Legislation
Boris Johnson Urges Conservatives to Ignore Farage
SNP Ordered to Update Single-Sex Space Guidance Within Days
Starmer Set to Reject Calls for Wealth Taxes
Stolen Century-Old Rolls-Royce Recovered After Hotel Theft
Macron Presses Starmer to Recognise Palestinian State
Labour Delayed Palestine Action Ban Over Riot Concerns
Swinney’s Tax Comments ‘Offensive to Scots’, Say Tories
High Street Retailers to Enforce Bans on Serial Shoplifters
Music Banned by Henry VIII to Be Performed After 500 Years
Steve Coogan Says Working Class Is Being ‘Ethnically Cleansed’
Home Office Admits Uncertainty Over Visa Overstayer Numbers
JD Vance Questions Mandelson Over Reform Party’s Rising Popularity
Macron to Receive Windsor Carriage Ride in Royal Gesture
Labour Accused of ‘Hammering’ Scots During First Year in Power
BBC Head of Music Stood Down Amid Bob Vylan Controversy
Corbyn Eyes Hard-Left Challenge to Starmer’s Leadership
London Tube Trains Suspended After Major Fire Erupts Nearby
Richard Kemp: I Felt Safer in Israel Under Attack Than in the UK
Cyclist Says Police Cited Human Rights Act for Riding No-Handed
China’s Central Bank Consults European Peers on Low-Rate Strategies
AI Raises Alarms Over Long-Term Job Security
Saudi Arabia Maintains Ties with Iran Despite Israel Conflict
Musk Battles to Protect Tesla Amid Trump Policy Threats
Air France-KLM Acquires Majority Stake in Scandinavian Airlines
UK Educators Sound Alarm on Declining Child Literacy
Shein Fined €40 Million in France Over Misleading Discounts
Brazil’s Lula Visits Kirchner During Argentina House Arrest
Trump Scores Legislative Win as House Passes Tax Reform Bill
Keir Starmer Faces Criticism After Rocky First Year in Power
DJI Launches Heavy-Duty Coaxial Quadcopter with 80 kg Lift Capacity
U.S. Senate Approves Major Legislation Dubbed the 'Big Beautiful Bill'
Largest Healthcare Fraud Takedown in U.S. History Announced by DOJ
Poland Implements Border Checks Amid Growing Migration Tensions
Political Dispute Escalates Between Trump and Musk
Emirates Airline Expands Market Share with New $20 Million Campaign
Amazon Reaches Milestone with Deployment of One Millionth Robot
US Senate Votes to Remove AI Regulation Moratorium from Domestic Policy Bill
Yulia Putintseva Calls for Spectator Ejection at Wimbledon Over Safety Concerns
Jury Deliberations in Diddy Trial Yield Partial Verdict in Serious Criminal Charges
House Oversight Committee Subpoenas Former Jill Biden Aide Amid Investigation into Alleged Concealment of President Biden's Cognitive Health
King Charles Plans Significant Role for Prince Harry in Coronation
Two Chinese Nationals Arrested for Espionage Activities Against U.S. Navy
Amazon Reaches Major Automation Milestone with Over One Million Robots
Extreme Heat Wave Sweeps Across Europe, Hitting Record Temperatures
Meta Announces Formation of Ambitious AI Unit, Meta Superintelligence Labs
Robots Compete in Football Tournament in China Amid Injuries
×