Final answer:
A solar eclipse occurs when the Moon crosses in front of the Sun, and a total solar eclipse happens when the Moon's umbra reaches Earth, completely obscuring the Sun. An annular eclipse, with a ring of light surrounding the Moon, occurs when the Moon appears smaller than the Sun.
Step-by-step explanation:
Understanding Solar Eclipses
When the Moon crosses in front of the Sun, it can sometimes completely hide the Sun. This phenomenon is known as a solar eclipse. During a total solar eclipse, the Moon's umbra (the darkest part of its shadow) reaches the Earth's surface, causing the Sun to be completely obscured. In this event, both the Sun and the Moon have nearly identical angular sizes in the sky, which is usually about 1/2°.
There is another type of solar eclipse known as an annular eclipse, which occurs when the Moon is slightly farther away from Earth. In this case, the Moon appears smaller than the Sun, and it does not cover the Sun completely, leaving a bright ring, or 'annulus', visible around the Moon's silhouette.
During a total eclipse, before the period of totality begins, there is a significant darkening of the sky, and some animals may behave as if it were twilight. Planets and brighter stars may become visible for a few minutes when the eclipse reaches totality. Solar eclipses are relatively rare for any given location on Earth, making them remarkable and spectacular events to witness.