Castor is a sextuple star system 51 light-years away in the constellation Gemini. What appears as a single star to the naked eye is actually six stars in three binary pairs.
Distance51 light-years
Star TypeSextuple star system
ConstellationGemini
Apparent Magnitude1.58
Time Dilation Formula Calculator
Journey Summary
Traveler's Time:
N/A years
Time experienced on the spacecraft
Observer's Time:
N/A years
Time passed on Earth
Maximum Velocity:
N/A c
Peak speed (as fraction of light speed)
Energy Required:
N/A J
Total energy needed for the journey
Speed vs Time
This chart shows how quickly you accelerate to a fraction of the speed of light over time.
Distance vs Time
Shows distance covered (in light-years) over time.
Traveler's vs Observer's Time
Shows how time experienced by the traveler differs from time on Earth.
Energy Requirement vs Distance
Shows the (simplified) energy requirements for maintaining relativistic travel as distance increases.
Doppler Shift vs Time
Shows how the Doppler effect changes observed wavelengths over time.
Velocity vs Distance
Shows how your speed changes as you travel further from your starting point.
Lorentz Factor vs Time
Shows how the Lorentz factor (γ) grows over time as relativistic effects increase.
Proper vs Observer Distance
Shows how distance measurements differ between the traveler's frame and the observer's frame.
Facts About Castor
At light speed, the journey would take 51 years
Castor was the first 'visual' double star discovered
Castor represents the mortal twin in the Gemini mythology
Notable For: One of the brightest multiple star systems
Frequently Asked Questions
How long to travel to Castor?
At light speed, it would take 51 years to reach Castor. At 1g constant acceleration with deceleration, a traveler would experience about 20 years.
Why does Castor have six stars?
Castor consists of three binary pairs. Two pairs of hot A-type stars orbit each other, while a third pair of cooler red dwarfs orbits the system at a greater distance.
This time dilation calculator lets you enter a distance in light-years and acceleration in m/s² to see how time dilation affects your journey. It shows differences between traveler and observer times, maximum velocity, energy requirements, Doppler shift, Lorentz factor, and how distances vary between reference frames. Charts appear after you calculate.
Results
Traveler's Time: How much time the person on the spaceship experiences
Observer's Time: How much time passes on Earth during the journey
Maximum Velocity: The highest speed reached, as a fraction of light speed
Interactive Charts
Speed vs Time: How quickly you accelerate towards light speed
Distance vs Time: How far you've traveled over time
Traveler's vs Observer's Time: Compare time passage between Earth and spaceship
Energy Requirement vs Distance: How much energy is needed as you travel further
Doppler Shift vs Time: How light wavelengths change during your journey
Velocity vs Distance: Your speed at different distances
Lorentz Factor vs Time: How much time dilation increases with speed
Proper vs Observer Distance: How distance measurements differ between frames
What is Time Dilation?
Time dilation is an effect from Einstein's theory of special relativity. The faster you move, the slower time passes for you compared to someone standing still. At 90% of light speed, time passes about 2.3 times slower for the traveler than for someone on Earth.
What is the Time Dilation Formula?
The Time Dilation Formula is:
t' = t / √(1 - v²/c²)
Where:
t' = time measured by the observer (on Earth)
t = time experienced by the traveler
v = velocity of the traveler
c = speed of light (299,792,458 meters per second)