Nasa astronaut says cause of medical emergency unknown as Artemis II Moon mission nears
Doctors have ruled out a heart attack or choking, but every other medical condition remains on the table
Greenhouse gases NOT to blame for prehistoric climate change, study of ice samples reveals
Previous research suggested carbon dioxide and methane helped drive plummeting temperatures around three million years ago
'Space archaeology' used for first time ever to trace the history of faraway galaxy
The research has raised questions about the evolutionary development of our own Milky Way galaxy
