An Erratum

A couple of days ago, in The Misfits, I quoted an energy of ~ 8 * 10^26 J for the plotline-demanded impact event.

Following on from a comment on this post, I’ve had occasion to re-check my figures. And I’ve discovered that they’re a bit off. I suspect I may have dropped a decimal place somewhere in the earlier analysis. Given that I was doing it at 11.30 at night, however, I’m hardly shocked! (I’ve edited the document to reflect the changes. Part of it, I think, was the classic school-boy error of forgetting that radius = 1/2 of the diameter. And of course volume goes by the cube of radius, so when I fed in the diameter where I meant the radius, that instantly inflated all the numbers by a factor of 2x2x2=8, and that’s *before* you get to decimal-place errors …)

The actual figure should be 4.3 * 10 ^ 25 Joules, so the impact will release about 6% as much energy as the two suns do per second, not 250%. However, this is still not good news. To put this in perspective, imagine a sphere of granite about 380 Km across (or about as big as some of the moons of Saturn). If the entire sphere was at a temperature of 20 C, an impact this energetic would be able to melt all of it. (Or heat it through 680 degrees C, which would take it to an even 700, which is about what Wikipedia claims for the temperature of lava…)

So to rephrase, this hypothetical impact can melt something the size of a Mimas.

It’s still not good news. And as such I still maintain that Minoris will lose its crust, although it may hang on to more atmosphere then I’d initially suggested. However it is safe to assume that once the thirty hours are up, it won’t be humanly-inhabitable anymore.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s

%d bloggers like this: