Skip to content


April 6, 2010

So everyone knows that Saturn’s moon Mimas looks kind of like the death star from STAR WARS. Wait, you didn’t know that? Ok here’s a picture.

Well when the Cassini orbiter flew past the moon two months ago, it measured the surface temperature using its composite infrared spectrometer. It turns out that the moon is extremely nerdy for a new reason. It’s also totally weird….

First off, here is a picture of the heat readings that scientists expected to receive.

This is what the temperature of Mimas should be like during the day. The more yellow it is, the higher the temperature, whilst the blue parts are cooler. The temperature is lower on the sides of the moon where it is the morning and evening and similarly low at the poles. When the data was collected the sun was shining right on the center of the moon so astronomers expected it to be hottest there.

Oh and by the way, when I talk about some bits of Mimas being hotter than other bits I don’t mean to suggest that anywhere on the moon is it actually warm, or even remotely balmy for that matter. For example, when I say that scientists expect the temperature to be warmer at the equator what I really mean to say is: “it should be slightly less horribly freezing at the equator than at the other parts of the moon which are also horribly cold and in no way hospitable for humans.” The difference in temperature on Mimas is the difference between -290 °F and -320 °F. Some areas might be warmer than other areas but in human terms it’s all VERY COLD INDEED.

Now for the interesting stuff. Here is a visualisation of the actual data.

As you can see, Mimas is currently in the process of being eaten by Pac-Man. This is clearly really cool. It’s also kind of weird. For a start, the temperature variations are not what astronomers predicted: the moon is hotter at the poles and at the side going through the early morning and colder in the central region, in which it was the middle of the day. A total reversal of what scientists expected to see. Finally, there is a sharp temperature gradient (that yellow v-shaped thing) where there should be a smooth transition from hot to cold. There’s also no visible difference in terrain or surface texture that could account for this discrepancy. Weird.

So why is Pac-Man eating Mimas? No-one’s quite sure, maybe there is a difference in the surface stuff. The warm areas might be composed of a substance that takes a long time to cool off whilst the areas that are cooler might consist of a substance that heats up rapidly but also loses its heat quickly. Alternatively, the surface of the relatively cool area might be highly reflective. When the sun’s rays hit the surface they bounce off it never warms up. Of course, this is just speculation, the scientists won’t know for sure until more temperature readings are taken of Mimas at different times of the day. Whatever the result, i’m willing to bet five whole pounds that it will be pretty interesting stuff. I am afterall, extremely poor.

And finally, regarding these recent discoveries, Cassini imaging team leader Carolyn Porco had this to say:

After much deliberation, we have concluded: Mimas is not boring. Who knew?!


The NASA news release.

An in-depth description of the data.

The Cassini team’s blog.

One Comment leave one →
  1. August 26, 2010 1:46 pm


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: