Hobbies And Interests
Solar Eclipses and the New Moon
Solar eclipses can only take place at new moon. During the new moon, the illuminated surface of the moon is not visible because it is in between Earth and the sun. However, only rarely is the moon in a direct enough line between the Earth and the sun for the resulting shadow to fall on the Earth's surface.
Partial Eclipses
A true partial eclipse takes place when the moon passes between the sun and the Earth at an angle that obscures only part of the sun's disc. This results in a semicircular shadow creeping across the sun and growing larger before dwindling and vanishing. Partial solar eclipses are much more common than total solar eclipses. At least one and up to five solar eclipses can happen within a year. A total solar eclipse is only visible from Earth every two years on average.
Annular Eclipses
An annular eclipse is a specific form of a partial eclipse. During an annular eclipse, the moon passes through the center of the sun's disc, just as it would during a total solar eclipse. However, because of the elliptical nature of the moon's orbit, it can appear smaller or larger from Earth at different times. When the moon's apparent size is less than that of the sun, the edges of the sun are still visible around the edges of the moon during what would otherwise be a total solar eclipse. This is an annular eclipse.
Partial Eclipse Safety
Partial eclipses are dangerous to observe directly because the portion of the sun that is not covered by the moon's shadow remains too bright to view directly. Visible and ultraviolet radiation can cause damage to the unprotected retina and cornea if a partial eclipse is directly observed. Partial solar eclipses can be safely observed using the pinhole method: A sheet of poster board with a pinhole can be used to project the eclipse onto a second sheet of poster board, allowing observers to watch the eclipse without endangering their vision.