Welcome to another Science Explainy Bit episode of the Urban Astronomer Podcast. Today we try to figure out just what an "orbit" actually is. Is it really as simple as they said in primary school? How does gravity, which normally pulls things down, work to keep the Moon in space? Download this episode now, to find the answer, and also learn a little about my upcoming appearance at ScopeX!
What is an Orbit? (1:28)
This turns out to be quite a simple topic - much simpler than why planets are always round, which we covered last month. In fact I struggled to stretch the core idea out long enough to fill an episode! All I really want to do here is explain how things stay up and why they go around, without resorting to the inaccurate "Centrifugal Force" explanation. You know the one? Where you ask people to fill a bucket, and then spin it around? The bucket swings around them without spilling any water, and then you wave your hands and say "That's how orbits work, except that there's no handle on the bucket, just gravity".

The truth, however, is so much cooler than that, so if you want to skip straight to the answer, click the timestamp above!
ScopeX (14:48)
ScopeX is an annual telescope and astronomy expo held in Johannesburg, South Africa. It features a huge display of amateur-built telescopes, commercial stands where you can buy telescopes, binoculars and cameras. There are also science shows and robotics displays. One of the highlights for me has always been the series of public lectures, in the auditorium. This year I will be giving the final talk of the day, where I'll talk about orbits. It won't just be a repeat of what you've heard here, though. I'll dig deeper, into the world of orbital mechanics and showing the strange, intuitive maneuvers that are needed to move around in space. And to make it easy to understand, I'll do it through the medium of video games!

If you'd like to attend, it's on 14 September from 9am to 9pm at the Museum of Military History in Saxonwold, Johannesburg. My talk starts at 3pm, and you're welcome to come introduce yourself afterwards!