Are cell mutations always bad? A mutation is a change in the genetic material of an organism. We are made from trillions of cells, each with a nucleus composed of DNA â a set of instructions that tells the cell what to do. Cells copy themselves with astonishing accuracy, but every now and then a piece of code is copied incorrectly.
Seven eclipses occur in a minimum of 12 lunar months (about 354.37 days). Given that the calendar year is only about eleven days longer than 12 lunar months, the first of the seven eclipses has to come in early January for the seventh eclipse to occur before the end of the year.
Lunar Eclipse. A lunar eclipse occurs when the Earth's shadow falls on the Moon, and a solar eclipse occurs when the Moon's shadow falls on the Earth. A look at the geometry of Moon phases would make it appear that a lunar eclipse should happen at every full moon and a solar eclipse at every new moon. This does not occur because the plane of the Moon's orbit is tilted 5.2Â° with respect to the plane of the Earth's orbit around the Sun (the ecliptic plane). The conditions for eclipses occur only at the points at which the Moon's orbit passes through the ecliptic plane.