Oh, and in a similar vein, “impact” is a noun, not a verb… (But then, I’m only saying this to annoy you in the hope that PZ will pay me for doing so…)

Au contraire, mon frére. “Impact” is both a noun and a verb: http://www.askoxford.com/concise_oed/impact?view=uk

Phil, nice video, but when you say the temperature of Mercury is 700 degrees, what’s that in real money? (Approx. 300C, if anyone asks.)

Actually, it is 371.111 °C: [°C] = ([°F] – 32) / 1.8

Yeah, I know — THANK YOU MR. SPOCK!

Wikipedia: “The United Kingdom completed its legal transition to SI units in 1995, but a few imperial units are still in official use: draught beer must be sold in pints, road-sign distances must be in yards and miles, clearance heights must be in feet and inches (although an equivalent in metres may be shown as well) and speed limits must be in miles per hour”

At least they started the process somewhere. Still going to take a while to sink in, sure.

Thanks!…………………………Thanks!

……………….Thanks………………………………Much appreciated………..will check it out.

If that’s true, then why do they use Imperial measures on “Doctor Who”?
When the 9th doctor describes the Earth’s movement to Rose, he uses “miles per hour” in his description.

@Chip,

The description you mention of the sunrise and sunset on Mercury can be seen on the website “The Nine Planets” (the maker of the site didn’t bother to change the URL to reflect what the IAU says).

The effects are caused by changes of Mercury’s velocity around the sun and the speed of it’s rotation, IIRC. It moves faster on it’s closest approach so much that the sun appears to set again. When Mercury moves away, the rotation catches up.

You just need to balance it off with some dynamo theory

The final explanation is an active dynamo (the same way Earth, Jupiter, Ganymede, Saturn, Neptune, and Uranus get magnetic fields). Essentially conducting fluid moves in complex enough motions to regenerate a magnetic field against resistive decay. Despite being the right answer (probably) there are two problems with the dynamo hypothesis

a) Mercury should have been frozen solid by now, you need liquid conductors for a dynamo
b) The magnetic field, while strong for crustal magnetism, is weak for a dynamo (1/100th that of Earth)

We can get around (a) by assuming there is a bit of sulphur (or some light element) in the core which would depress the freezing point of iron in the core and allow a little to remain liquid.

(b) is harder, there are a few theories from thin shell models (there is a really thin layer of conducting fluid) to thick shell models with a giant stable layer at the top of the core (a region that is resistive to moving at all).

Anyways, everyone in the planetary magnetism community is anxiously awaiting the time when MESSENGER will orbit, so we can resolve features of the magnetic field and make better models.

I also wanted to say, “Well done Phil!” This is the kinda stuff everyone needs to see and hear about space science.

And as for his enunciation, I think it’s cool. Having a host of any science program get as excited about what they’re talking about as Phil does, well, that just gets everyone watching excited too.

*Now press submit*

Just be glad it’s not in Kelvin.

But yeah, at least subtitles with the metric values would help in two ways – it would be easier for the other 6.5 billion people to understand them, and it would little by little show the united statians that, well, their metrics suck.

[...]but these are designed primarily for American audiences.

I’m shaking my head in disbelief. When will Americans realise that there are more people in this world than just themselves and that the rest of us actually have running water, electricity, and even internet connections?

FYI it’s called the WORLD Wide Web for a reason.

I guess the US will eventually move into the 21st C., kicking and screaming all the way, round about the year 2100…

[dons flame-proof suit]

J/P=?

Thanks for the positive comments!

And Phil, I’ve been off the tubes for a few weeks and have just heard via the SGU that you are the new President of the PPEF (formerly the JREF). Belated congratulations!!