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.
Eclipses (up to three) occur during an eclipse season, a one-or two-month period twice a year, around the time when the Sun is near the nodes of the Moon's orbit. An eclipse does not occur every month, because one month after an eclipse the relative geometry of the Sun, Moon, and Earth has changed.