Climate change. no one really knows yes people say this and that but we go off of what they say.
Although I don't know for sure what is an epicycle, I think your answer is right and I would try to explain as apliable to solar systems on the Milky Way known through astronomical discoveries, conside ring just one star called "Sun" and a few distant planets describing a certain type of movement around it. I should add that the Moon describes the same type of movement around the Earth ( which is not a star), being the only natural satelite of the planet Earth, being kept around it by the circumstances created by the proportion of forces occured while moving
C12 and C14......C12.…...C14 is used for carbon dating..,...carbon can be involved in the spread of toxic substances within a food chain (biomagnification).......carbon is capable of form single, double, triple, and quadruple bonds; it is very versatile in regards to its bonding capability, which is why carbon is so crucial to life
The Hydrogen bonds connecting base pairs must be broken.