What Is a Total Solar Eclipse?

What Is a Total Solar Eclipse?

Total solar eclipses occur when the Moon comes between the Sun and the Earth and casts the darkest part of its shadow (the umbra) on Earth. The darkest point of the eclipse is almost as dark as night.

During a total eclipse of the Sun, the Moon covers the entire disk of the Sun. In partial and annular solar eclipses, the Moon blocks only part of the Sun.

 

Not Total Everywhere
Eclipses are named after their darkest phase. If a solar eclipse is total at any point on Earth, it is called a total solar eclipse, even though it’s seen as a partial eclipse in most parts of the world.

 

5 Phases

There are 5 stages in a total solar sclipse:

Partial eclipse begins (first contact): The Moon’s shadow starts becoming visible over the Sun’s disc. The sun looks as if a bite has been taken from it.

Total eclipse begins (second contact): Almost the entire disc of the Sun is covered by the Moon. Observers in the path of the Moon’s umbra may be able to see Baily’s beads and the diamond ring effect.

Maximum eclipse or totality: The Moon completely covers the disc of the Sun. Only the Sun’s corona is visible. This is the most dramatic stage of a Total Solar Eclipse. At this time, the Sky goes dark, temperatures fall drastically and birds and animals often go quiet.

Total eclipse ends (third contact): The Moon’s shadow starts moving away and the Sun reappears.

Partial eclipse ends (fourth contact): The Moon stops overlapping the Sun’s disc. The eclipse ends at this stage.

 

Protect Your Eyes!
Never look directly at the Sun, eclipsed or otherwise, without proper protective eyewear. The Sun’s UV radiation can burn the retinas in your eyes, and cause permanent damage or even blindness.

 

Be Safe: DIY Pinhole Projector
The only way to safely see a solar eclipse is to wear protective eclipse glasses or to project an image of the eclipsed Sun using a pinhole projector.

 

Special Sights at Totality
Certain phenomena can only be seen during a Total Solar Eclipse:

Baily’s beads: Seen about 10-15 seconds before and after totality, Baily’s beads are little bead-like blobs of light at the edge of the Moon. These happen because the gaps in the mountains and valleys on the Moon’s surface allow sunlight to pass through in some places but not others.

Diamond ring: As the Moon moves to cover the entire disc of the Sun, Baily’s beads disappear, leaving one last bead a few seconds before totality. At this point in the eclipse, the Sun’s corona forms a ring around the Moon. The ring around the Moon and the leftover Baily’s bead gives the appearance of a diamond ring.

The Sun’s chromosphere: The Sun’s atmosphere has 3 layers: the photosphere, the chromosphere and the corona. The chromosphere, which gives out a reddish glow can only be seen for a few seconds right after the diamond ring disappears during a total eclipse of the Sun.

The Sun’s corona: Like the chromosphere, the Sun’s corona is only visible during a Total Solar Eclipse. It can be seen as a faint ring of rays surrounding the dark Moon during totality.

Shadow bands: About one minute before and after totality, moving wavy lines of alternating light and dark can be seen on plain-colored surfaces. These shadow bands are the result of the light emitted from a thin solar crescent being refracted by the Earth’s atmosphere.

 

Source:
timeanddate.com