What Are Eclipses?

• Eclipses are astronomical events where a celestial body partially or totally covers another celestial object. 

• From Earth, we can see 2 types of eclipses – eclipses of the Sun (solar eclipses), and eclipses of the Moon (lunar eclipses).
• For either of the eclipse to take place, the Sun, the Moon, and Earth must be aligned in a perfect or near perfect straight line–an alignment astronomers call syzygy.

What are Solar Eclipses?

• An eclipse of the Sun occurs when the New Moon moves between the Sun and Earth, blocking out the Sun’s rays and casting a shadow on parts of Earth.
• The Moon’s shadow is not big enough to engulf the entire planet, so the shadow is always limited to a certain area.
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• This area changes during the course of the eclipse because the Moon and Earth are in constant motion.
• Also on average, the same spot on Earth only gets to see a solar eclipse for a few minutes about every 375 years.
• The solar eclipse should not be looked at directly as the Sun’s UV radiation can burn the retinas in eyes leading to permanent damage or even blindness.

Types of Solar Eclipses

There are 4 different types of solar eclipses. How much of the Sun’s disk is eclipsed, the eclipse magnitude, depends on which part of the Moon’s shadow falls on Earth.

• Partial solar eclipses occur when the Moon only partially obscures the Sun’s disk and casts only its penumbra on Earth.

• Annular solar eclipses take place when the Moon’s disk is not big enough to cover the entire disk of the Sun, and the Sun’s outer edges remain visible to form a ring of fire in the sky. An annular eclipse of the Sun takes place when the Moon is near apogee, and the Moon’s antumbra falls on Earth.
• Total solar eclipses happen when the Moon completely covers the Sun, and it can only take place when the Moon is near perigee, the point of the Moon’s orbit closest to Earth. In a total solar eclipse, the Moon casts its darkest shadow, the umbra.
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• Hybrid Solar Eclipses, also known as annular-total eclipses, are the rarest type. They occur when the same eclipse changes from an annular to a total solar eclipse, and/or vice versa, along the eclipse’s path.

Why every New Moon does not cause a solar eclipse?

There are 2 reasons, why isn’t there a solar eclipse every New Moon night;

1. 1. 1. The New Moon has to be near a lunar node. These nodes are the 2 points where the plane of the Moon’s orbital path around Earth meets Earth’s orbital plane around the Sun–the ecliptic. The paths meet because the plane of the Moon’s path around Earth is inclined at an angle of approximately 5° to the ecliptic.
      2. The Sun must also be close to a lunar node so it can form a perfect or near-perfect line with the Moon and Earth. This alignment occurs a little less than 6 months apart, and it lasts, on average, around 34.5 days. It is only during this time–the eclipse season–that eclipses can take place.

Lunar Eclipses

• The Moon does not have its own light but shines because its surface reflects the Sun’s rays.
• A lunar eclipse occurs when Earth comes between the Sun and the Moon and blocks the Sun’s rays from directly reaching the Moon.
• The Sun casts the Earth’s shadow on the Moon’s surface.
• Total lunar eclipses happen only when:

1. 1. 1. It is Full Moon.
      2. At the same time, the Moon is at (or very near) a lunar node, so the Sun, the Moon, and the Earth are aligned in a straight (or nearly straight) line.

• Almost everyone on the night side of Earth can see a total eclipse of the Moon.
• Because of this, most people have higher chances of seeing a total lunar eclipse than a total solar eclipse, even though both occur at similar intervals.
• Unlike solar eclipses, observing a total lunar eclipse does not require any special equipment. Lunar eclipses are safe to see with the naked and unaided eye.
• About 35% of all lunar eclipses in a calendar year are total lunar eclipses. On average, a total lunar eclipse can be seen from any given location every 2.5 years.

Types of Lunar Eclipses

There are 3 kinds of lunar eclipses: total, partial, and penumbral.

1. A total lunar eclipse occurs when Earth’s umbra – the central, dark part of its shadow – obscures all of the Moon’s surface.
2. A partial lunar eclipse can be observed when only part of the Moon’s surface is obscured by Earth’s umbra.
3. A penumbral lunar eclipse happens when the Moon travels through the faint penumbral portion of Earth’s shadow.

Why in News?

• A rare celestial event, an annular solar eclipse, which is popularly known as the “ring of fire” eclipse, was visible on June 21, 2020 in parts of India.
• The annular phase was visible only in few places of northern India, while the rest of the country witnessed this event partially.