-500F is about 40 degrees F colder than absolute zero. It has never been that cold anywhere in the universe. -200F is certainly more “actually possible in our current understanding of physics”, but it’s over 100 degrees colder than the current Martian temperature and thus also not a temperature it’s ever been on Earth, even at the heart of the coldest Ice Age directly on the poles. While Earth’s average temperature has certainly fluctuated, the temperatures you’re talking about are so cold that all life on Earth would have gone extinct.
-500F is about 40 degrees F colder than absolute zero. It has never been that cold anywhere in the universe. -200F is certainly more “actually possible in our current understanding of physics”, but it’s over 100 degrees colder than the current Martian temperature and thus also not a temperature it’s ever been on Earth, even at the heart of the coldest Ice Age directly on the poles. While Earth’s average temperature has certainly fluctuated, the temperatures you’re talking about are so cold that all life on Earth would have gone extinct.