"A freak of Nature," insisted the first one. "You've heard of the Land of the Midnight Sun. What's so different about this?"
"Everything!" said Henry.
They all looked at him, startled, including Uncle Andy.
Henry addressed Dr. Bauml. "As an astronomer you will understand the nature and importance of the ionosphere," he said, amidst raised eyebrows all around. "It is that layer of the atmosphere which protects us from the dangerous short radiations from the sun. These quanta, striking atoms of oxygen, create ionized oxygen and ozone, forming the ionosphere. Such atoms are necessarily in such rapid motion that they would be lost in space were it not for the magnitude of Earth's gravitation. That is why Earth bears—or bore—a high form of intelligent life whereas Mars must continue to lose its ionized oxygen into space and could therefore not support a high form of life."
"Yes, yes!" exclaimed Bauml, impressed. "But what has that to do with the present?"
"Venus does not have an ionosphere," continued Henry. "Otherwise it would have shown up in spectrographs. Its atmosphere is caused largely by violent volcanic action. Volcanoes, incredibly heated storms and no ionosphere, spells no oxygen and no life. Therefore, conclusion number one: We are still on Earth."
Several congressmen snorted. "Who said we weren't?"
"Go on!" encouraged Bauml, while Dr. Edwards began to listen in some surprise. "I agree so far! This is Earth, but where do we go from here?"
"Let us disregard, for the moment," said Henry, "that there is no night. Just concentrate on the fact that we can't see the sun at any time, clouds or no clouds. Ergo, the ionosphere has changed its composition. It would take millions of years to do that, just as it took billions of years to build it up in the first place. I submit that the sun has cooled and the ionosphere is much thicker than it was before, thus acquiring different characteristics of refraction which reflect light back to Earth. It is almost like a mirror. Just as it once reflected radio waves back, it now shuts out the shorter wavelengths, including light, itself. I submit further, that if the sun were still bright we should notice a difference in relative brightness between day and night. Inasmuch as there is no difference, I say that the sun is now grown dim and feeble, and that we have traveled perhaps a billion years into the future."