From within the Moon's penumbra, a partial solar eclipse can be seen. Like any other opaque objects illuminated by a light source, the Moon and the Earth cast shadows into space as they block the sunlight that hits them. Each shadow has 3 different areas: the umbra, the penumbra, and the antumbra.
<span>The heart contains four chambers: upper left atria, upper right atria, lower left ventricle and the lower right ventricle. Oftentimes, the right atria and right ventricle are together referred to as the "right heart" and the left atria and left ventricle are referred to as the "left heart", however there are still four separate chambers.</span>
Sister chromosome exchanges are recombination events that occur between homologous chromosomes and are often the result of exposure of the cell to DNA damaging agents.
Cross over, or recombination, is the exchange of chromosome segments between non sister chromatids in meiosis. Crossing over creates new combinations of genes in the gametes that are not found in either parent, contributing to genetic diversity.
