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.
High School Earth Science/The Sun and the Earth-Moon System - A Lunar Eclipse. 1  A lunar eclipse occurs when the full moon moves through the shadow of the Earth (Figure 24.25). This can only happen when the Earth is between the Moon and the Sun and all three are lined up in the same plane, called the ecliptic.