Codon Codon is a combination of three successive nucleotides in a DNA or RNA strand. All the nucleic acids, DNA and RNA, have nucleotides sequenced as a set of codons. Each nucleotide consists of a nitrogenous base, one of A, C, T/U, or G.
Phases of the moon are simply how much sun is hitting the surface of the moon, with the moon being between the earth and the sun. Lunar eclipses occur when a conjunction between the earth and the sun... with the earth casting a shadow on the full moon.
The moon has four basic phases: new moon, first quarter, full moon and third quarter. Since the moon doesn't emit its own light, it's only illuminated by sunlight. The dark section of the moon is the portion that is facing away from the sun, and only during a lunar eclipse is the Earth's shadow cast upon the moon.