# Travelling through the universe

As Douglas Adams once said, space is big. Really big. You just won’t believe how vastly, hugely, mindbogglingly big it is. Luckily, Dr Jenny Shipway and the team at the Winchester Science Centre decided to take on the challenge and worked out how long it would take to travel to places like the Moon, Neptune and Proxima Centauri by spaceship, car and even foot!

You can see it for yourself in How It Works when issue 66 hits the shops next month.

Jenny Shipway: It’s really difficult to grasp the true scale of the universe; the scale is just too huge. Even relatively short distances like 40 trillion kilometres (the distance to our next-door star, Proxima Centauri) are impossible to imagine. Using journey time is a great way make these huge distances more accessible, and also makes it easy to appreciate why we’ve never sent spacecraft to any object outside our Solar System!

How long did all the maths take?

Shipway: I didn’t do it by hand! I created a spreadsheet that did the calculations for me. It probably took about an hour to get it all set up and looking nice. Finding the numbers to put in can take time, but I knew where to find these.

First I entered a list of the speeds of different modes of transport, using formulae to automatically convert these all to kilometres per hour. I then added a list of destinations and converted their distances into kilometres.

Finally, I wrote some equations that work out all the travel times for me! It also lets me change the unit (hours, days, years etc) so I can get sensible numbers – saying something takes 3,000,100 hours isn’t so helpful. Now this is set up, it’s very easy to add new destinations or new forms of transport and watch the answers pop up as if by magic.

Did anything surprise you when putting this all together?

Shipway: I use numbers like these in our planetarium shows so I knew roughly how long these journeys take, but it was a good exercise to recalculate them all and get the full set!

Firstly, I had to stop and think about what speed to choose for the Voyager 1 spacecraft, as its speed has changed a lot. In the end I chose the speed at which it passed the edge of the Sun’s magnetic field in 2012, a little slower than its maximum speed (61,355 vs 62,136 kilometres per hour). This speed will not change a lot in the coming years as it feels very little gravity from the Sun, being so far away.

That sounds fast – and it is – but it just shows up how ridiculously fast the Helios spacecraft was (almost four times faster than Voyager). Unbelievable! This was possible because Helios was [accelerated] by the gravity of the Sun as it whipped around it in an orbit that went even closer in than the planet Mercury.

But most of all, working on this just made me glad that the planetarium lets me break the rules of physics and fly people through the universe faster than light, else we’d have very, very, VERY long shows!

Live science shows will be taking place at the Winchester Science Centre throughout the October half term.