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.
Castor is 51 light-years from Earth. That is about 482 trillion km (300 trillion miles), or 3.23 million astronomical units.
| Unit | Distance |
|---|---|
| Light-years | 51 |
| Kilometers | 482,000,000,000,000 km |
| Miles | 300,000,000,000,000 miles |
| Astronomical units (AU) | 3,230,000 astronomical units |
| Parsecs | 15.6 |
Light from Castor takes 51 years to reach Earth, so the light you see tonight left Castor 51 years ago.
Voyager 1, the fastest object humans have sent into deep space, travels at about 17 km/s. It would need about 899,400 years to cover this distance.
Notable For: One of the brightest multiple star systems
At light speed, it would take 51 years to reach Castor. At 1g constant acceleration with deceleration, a traveler would experience about 20 years.
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.
Castor is 51 light-years from Earth, which is about 482 trillion km or 300 trillion miles. Light from Castor takes 51 years to reach us.
Castor is 51 light-years from Earth. One light-year is about 9.46 trillion km, the distance light travels in one year. In parsecs, Castor is about 15.6 parsecs away.
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.
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.
The Time Dilation Formula is:
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)