Final answer:
The coldest temperature recorded in the USA is warmer than Mars' average night temperature but colder than its average daytime temperature. Mars' wide temperature swings are due to its thin atmosphere and the absence of oceans and clouds for moderation.
Step-by-step explanation:
To answer which is warmer - the coldest temperature recorded in the USA or the average temperature on Mars - let's look at the data. The coldest recorded place on Earth's surface is Vostok, Antarctica at 183 K (-89°C). On the other hand, on Mars, temperatures near the equator can vary greatly, with an average of -135 °C at night to an average of 30 °C during the day. Therefore, the coldest temperature recorded in the USA is warmer than the average night temperature on Mars but colder than the average daytime temperature near the martian equator.
The wide difference in temperature on Mars compared to Earth can be explained by Mars' thin atmosphere which is mostly carbon dioxide and is so thin that it resembles Earth's atmosphere at an altitude of 30 kilometers (100,000 feet). This thin atmosphere does not retain heat effectively, leading to drastic temperature swings. Mars also lacks moderating oceans and clouds, which contribute to these sharp temperature contrasts.