Having spent 9 months getting there, twin B discovers that this is a very dull brown dwarf star. Twin B turns the spaceship around and immediately heads back home.
The story is now repeated. During acceleration, twin A's clocks all start to show different times. This time it is twin A's clock back on earth that starts moving forward rapidly.
During the journey, all of twin A's clocks appear to be running slow. Once back home, B decelerates again. This time it is the clock on the star that gets a sudden boost.
As you can see, both twins see the others' clocks moving slower during the journey. They are able to agree on the final times because B took account of the rapid changes in A's clocks during the acceleration and deceleration periods.
When the twins are finally reunited, twin B really is a year younger than twin A.
start
prev
The story is now repeated. During acceleration, twin A's clocks all start to show different times. This time it is twin A's clock back on earth that starts moving forward rapidly.
During the journey, all of twin A's clocks appear to be running slow. Once back home, B decelerates again. This time it is the clock on the star that gets a sudden boost.
As you can see, both twins see the others' clocks moving slower during the journey. They are able to agree on the final times because B took account of the rapid changes in A's clocks during the acceleration and deceleration periods.
When the twins are finally reunited, twin B really is a year younger than twin A.
start
prev
