The distances in space are enormous, and the time that it takes to travel, even within our Solar System, between celestial objects is huge. Science fiction gives us warp drives and hyperspace to leap around the galaxy, and maybe one day we’ll figure out how to fold space and teleport ourselves around the universe. Until then, we are stuck with the laws of physics and the universe’s speed limit, the speed of light.
But what if we could go really fast? What if we had a way to reach relativistic speeds? With the simulator below, you can explore how long it would take to get to various places in the universe from both the point of view of an observer on Earth, watching a spaceship, and an observer in a spaceship capable of traversing the universe. You can also see how much energy would be needed.
On the left are some sliders you can adjust to set the parameters of your journey to the selected destination. The top two panels to the right of the sliders show the travel time of the spaceship as viewed from the Earth for the top panel and from the spaceship for the second panel. At velocities above 50% of the speed of light, you’ll see the difference in time taken for the journey between these panels increasing.
The energy required box shows how much energy it would take to accelerate to the selected velocity and then decelerate safely to reach the destination. The first figure is how many joules are required. The subsequent values in the box show energy in terms of the amounts consumed in New Zealand in one year (1.6e17 J) and globally (6e20 J). The final one is the energy as a proportion of the Sun’s output. This gives you some idea of the staggering amount of energy required to move a spaceship at relativistic speeds.
The two rows of panels show the journey as seen by two observers, one on Earth and one in the spaceship. For each, there is an acceleration phase, a cruise and a deceleration phase. You can adjust the acceleration in Gs (9.81 m/s^2) and the peak velocity in percentage of light speed to see what effect there is on the journey.
References
Featured image by Sam Leske, taken with a 300mm reflecting telescope at Star Safari Observatory in March 2026.
