I visited the moon websites offered in my other question, but didn’t find the answer to this:
The temperature on the moon ranges from -170ºF to +265ºF. If you were at the terminator (where day meets night) what would the temperature be? Is there a “gray” area of temperature? Or is it exactly hot or cold (depending on which side you were on)?
Also, would there be any effect on the Earth if the moon rotated at a different speed? That is, we wouldn’t just see one side.
When the sun is directly overhead at lunar “noon” the sun’s energy is about 330 calories/sec/m[sup]2[/sup]. This is the maximum input energy. As the sun goes lower in the sky, toward the horizon, the energy that used to illuminate 1 sq meter now illuminates a larger area so the solar intensity goes down. When the sun reaches 60[sup]o[/sup] from verticle the intensity has dropped to 50% of the “noon” value. At 80[sup]o[/sup] from verticle the value is 17% and at 85 it is down to 8.7%. The surface of the moon will have cooled by radiation. Moon landing sites were near the terminator so that the surface wouldn’t put too much heat into the astronauts suits.
However, the sun isn’t striking the astronaut at such grazing angles so the suit is made of material that reflects most of the sunlight so as to prevent overheating and there is extensive cooling apparatus also. This site http://www.farhills.org/s/lees/space/apollo.htm has some information on how the astronauts were kept cool on the moon’s surface. NASA Apollo sites will have as much detailed information as you want.
Several people who worked on such projects visit the BadAstronomy board and you can ask there about how the moon suits worked and I’m sure someone will come up with information for you. http://www.badastronomy.com/phpBB/index.php I would post on the general astronomy board.
Measuring temperature on the moon is completely different that doing it on Earth. If I say it was 80 degrees F here today, that means that the air was 80 degrees F, measured in the shade so that the thermometer is heated by the air and not the sun.
On the moon, however, there is no atmosphere. That means you have to measure the temperature of something else. You could measure the temperature of the ground. The ground will be very hot during the day, for reasons pointed out by David Simmons, and will taper off as the sun goes down. The heat in the ground will then be dissipated by conduction through the ground, and radiated away as infrared.
So, I suppose you could say there is a gray area, or gradient of temperature. The ground wouldn’t instantly snap hot or cold when the sun rises or sets.
The lack of atmosphere really makes these measurements pointless. The temperature of an object sitting on the surface of earth is determined first by the air temperature, then by the heat being conducted into the earth and the heat coming from sunlight. On the moon, though, the lack of atmosphere means that only the conduction and radiation create the temperature.