View Full Version : Mercury!

04-01-2011, 02:15 AM
Pictures from NASA's Messenger spacecraft. http://www.liveleak.com/view?i=9e2_1301563591

04-01-2011, 02:29 AM
Could an astronaut walk on the surface, in the region of the terminator where it is not scorching hot nor way too cold?

04-01-2011, 05:15 AM
There is no atmosphere so there is no comfort zone. The illuminated side of an object will be at high temperature and the dark side at very low temperature. Stand in the sun and barbeque one side and freeze the other. Stand in the shade and freeze both sides.

mike os
04-01-2011, 07:20 AM
but given that the dark side is no colder than anywhere else in space........

04-01-2011, 07:28 AM
but given that the dark side is no colder than anywhere else in space........

My thoughts also, no different than "space walking" unless the surface is searing hot so the dark side should be ok.

04-01-2011, 07:56 AM
My understanding is that because of the close proximity of that particular planet to the sun and it's lack of atmosphere, there is an 1100 differential in temperature from the bright to the dark side. I don't recall if that was F or C, but I don't think it matters. There's not going to be any tours anytime soon.

04-01-2011, 08:41 AM
Plus there is no reason to go there.

04-01-2011, 09:12 AM
The temperature of space is about 3 degrees Kelvin. An object exposed to space and not illuminated by the sun will be radiating into an almost absolute zero heat sink. How cold it becomes depends on the emissivity of the object and any internal heat source. If it has no internal heat source then it will eventually cool to 3 Kelvin. If it does have a heat source then the temperature will depend on the rate of radiative loss vs the production of additional heat. At some point equilibrium is reached in any case. The rate of heat loss varies by the fourth power of the difference in temperature between the object and the surroundings modified by the emissivity of the object.

On Mercury the temperature on the dark side depends on the amount of heat that leaks through the mass of the planet from the sun side. The temperature of an object on the dark side depends on the above factors modified by the amount of exposure to the planet itself which is warmer than 3K. Again, thermal equilibrium will be reached. The dark side is cold enough that they are looking for water ice.

mike os
04-01-2011, 11:53 AM
at 3k...almost everything is frozen .... or sublimed into the vacum as there is no atmosphere.

in theory it is no colder than the dark side of the moon ( no floyd jokes please) or any other planet(oid) with little or no atmosphere.... sun side... well I cant see anyone going there in the next few weeks:rolleyes:

Deja Vu
04-01-2011, 12:13 PM
Gee! Upon noticing the title before investigating, I had a flashback of last summer's garage sale when my eyes gazed down and saw an old thermostat...Mercury!, I exclaimed to myself before snapping it up for a buck.