After last week’s dark matter post in which I mentioned that the outer planets are orbiting more slowly than the inner ones due to Kepler’s third law, Jim commented
In my head Neptune was going super-fast but over a gigantic distance which explained the longer time.
BIG MISTAKE.
And now, the thing that indirectly led to last week’s post on Race Into Space: the Kerbal Space Program.
Jiiiiim asks
So, put a grapefruit and an egg in an area of space which has no other gravitational influences. Would they orbit each other and what would that orbit look like?
It rather depends on the initial parameters of the system, but assuming no other information my answer is going to be absolutely not.
Barycentre, barycentre. It’s the kind of word that sounds like it should be easy to pun, but really isn’t.
Warning: post contains moderately difficult algebra along with hints of calculus. But don’t worry, it’s not that bad.
Rockets are kind of sucky for getting into space. Right now, though, they’re all we’ve got.
Edit: I forgot the best orbit of all, the Hohmann transfer orbit. This has now been amended.
Yes yes I’m twenty minutes late. Sue me. It occured to me while thinking of ideas for future science articles that it might be useful to talk about satellite orbits for a little bit so that I have some explanations on hand for why LEO sucks and why geostationary orbit is hard. There’s no ultimate conclusion here, just background information on the most common types of satellite orbit and their advantages/disadvantages. Enjoy.
RRRrrrrrssssssssssnnnnnncccccccceeee.
I’m sorry, I was doing an impression of a resonating object there, mainly because I feel that starting with a description of what resonance is would be pointless. Everyone knows what “to resonate” means, and as far as physical principles goes all schoolchildren get taught about Galileo Galilei and oscillating pendulums when they’re doing their GCSEs. Basically if you have something undergoing a persistent, periodic motion, then it will transfer and store energy with more efficiency at certain specific frequencies resulting in a greater amplitude of motion. Most people understand this in the context of pendulums, as above – where, if you release a pendulum and let it settle for a few seconds, it will eventually swing with a period 
where l is the length of the pendulum and g is the pendulum’s acceleration due to gravity.