We know that the Solar System is big. Really, really big. But how does Earth fit into this clockwork of neighbouring planets?
A new project is helping cyclists explore this question by taking their bikes on a metaphorical journey through space and time.
The project, called the Interplanetary Cycle Trail, is a 100-million-to-one model replica of the Solar System running along the Otago Central Rail Trail. At this scale, one centimetre on the trail is 1000 kilometres in space.
The trail begins with a massive 14-metre Sun at Ranfurly and ends with a tiny 2.4-centimetre Pluto close to Clyde. The scaling down doesn’t just apply to distance and size however. It works with time too. At this scale, cyclists who reach 11 kilometres per hour are actually travelling faster than the speed of light.
Having such a precise model of our Solar System as a cycle trail is the brainchild of Cromwell local Ian Begg. Ian is the grandson of John Campbell Begg, who co-founded the Beverly-Begg observatory in 1922, as the southernmost observatory of its day.
Ian had been mulling over this idea for four years. Now, in collaboration with the Otago Central Rail Trail Trust, Otago Museum and the Dodd-Walls Centre, it has finally come to fruition.
“I am delighted to see it come to life,” Ian says. “The scale of our solar system is quite extraordinary, and text books simply can’t do it justice. The Central Otago landscape also provides a perfect setting for contemplating the vastness of our Solar System and our place in it.”
The project is currently in its pilot phase, which has come with some hurdles as well as exciting moments.
“For me, the biggest challenge was the Sun. We couldn’t readily build a Sun that was three stories high!” says Craig Grant, Director of Science Engagement at Otago Museum. “Ian instead came up with the idea of riding through the Sun, using bright yellow rope to mark it out as a temporary installation.”
Craig points out that, according to Wikipedia, this is the largest bikeable model of the Solar System in the world and that the next largest is only half its size at a scale of 200-million-to-one. With Clyde a 90-kilometre bike ride from Ranfurly – longer than two marathons back to back – it probably feels like it too.
The latest development is that DOC (Department of Conservation) and the Otago Central Rail Trail Trust have agreed to make this unique installation a permanent feature of the Central Otago landscape.
Mike Tubbs, Otago Operations Manager at DOC, tells us, “I think the scale solar system adds a new dimension and point of interest to users of the rail trail. Over the trial period we’ve had only positive feedback from users and we’ve also been impressed with how well the design and construction used fit in with the trail and landscape.”
The next step now will be to extend the interplanetary bike route east from Ranfurly to Middlemarch, running along the rest of the Otago Central Rail Trail.
“We love it!” says Kate Wilson, Chairperson of the Trust. “The feedback we’re getting is very pleasing as it shows that even old cyclists are open to learning new things! We’re now working on the other transecting orbits, which are to be added in the next few months.
“The design of the sun is still tricky: a formidable 14 metre orb would be in keeping, but we’re looking at a variety of possible designs, including a sun dial.”
Craig adds, “It’s just great seeing how positively people react to this. And seeing how the likes of Jupiter and Uranus look in-situ against the skyscape and landscape – it’s an aesthetically spectacular view!”
Read more about the Interplanetary Cycle Trail on Otago Museum's blog.
The Interplanetary Cycle Trail is run by Ian Begg, the Otago Central Rail Trail Trust, Otago Museum and the Dodd-Walls Centre.
You can find out about other projects funded through the Unlocking Curious Minds contestable fund here.

Unlocking Curious Minds
Unlocking Curious Minds supports projects that excite and engage New Zealanders who have fewer opportunities to experience and connect with science and technology.