On March 14 the first lunar eclipse of the year took place. During the event, also witness a Blood moon, which gets its name as Earth’s only satellite turns red in colour. It was  visible across parts of Asia, Africa, Australia, South America, Pacific and parts of the United States.

LEARNING FROM HOME/ WITHOUT CLASSES/ BASICS

          Though the sun’s light blocked during an eclipse, some sunlight still reaches the lunar surface indirectly via the Earth’s atmosphere, bathing the Moon in a reddish, yellow, or orange glow.

                      As the Sun’s rays pass through the atmosphere, some colors in the light spectrum—those towards the violet spectrum—are filtered out by a phenomenon called Rayleigh scattering. This is the same mechanism that causes colorful sunrises and sunsets. Red wavelengths are least affected by this effect, so the light reaching the Moon’s surface has a reddish hue, causing the fully eclipsed Moon to take on a red color.

Rayleigh scattering

              In various situations, light can be scattered, i.e., sent into other directions. The term scattering  mostly used for diffuse scattering, where light sent into a wide range of directions. A classical example is scattering of light at a rough surface, having a microscopically irregular structure.

However, there also cases with stimulated scattering, where the direction of scattered light determined by some incident light.

Rayleigh scattering, named after Lord Rayleigh, is elastic scattering of electromagnetic radiation at particles which are much smaller than the wavelength of the radiation.

Elastic scattering means that the wavelength of the scattered light is not changed, apart from a possible Doppler shift due to the movement. That implies that the inner energy of the scattering particles is not changed;

ECLIPSE

                      An eclipse happens when a planet or a moon gets in the way of the Sun’s light. Here on Earth, we can experience two kinds of eclipses: solar eclipses and lunar eclipses.

                   A solar eclipse occurs when the moon passes in a direct line between the Earth and the sun. The moon’s shadow travels over the Earth’s surface and blocks out the sun’s light as seen from Earth. A solar eclipse happens when, at just the right moment, the moon passes between the sun and Earth. Sometimes the moon only blocks part of the sun’s light. This called a partial solar eclipse.

‎Other times, the moon blocks all of the sun’s light. This called a ‎‎total solar eclipse‎‎. As the moon blocks the sun’s light, it casts a shadow on part of the Earth.‎

‎                The moon’s shadow creates a trail as Earth rotates. This trail called the path of totality. If you want to experience total darkness during an eclipse, you have to be in the path of totality.‎

The moon’s shadow has two parts: a central region (umbra) and an outer region (penumbra). Depending upon which part of the shadow passes over you, you will see one of three types of solar eclipses:

• Total – The entire central portion of the sun blocked out.
• Partial – Only part of the sun’s surface blocked out.
• Annular – Only a small, ring-like sliver of light seen from the sun’s disc.

                                If the umbra passes over you, the entire central portion of the sun will blocked out. You will see a total solar eclipse, and the sky will darken as if it were night time. During a total solar eclipse, you can see the sun’s outer atmosphere, called the corona. In fact, this is the only time that you can see the corona, which is why astronomers get so excited when a total eclipse is about to occur. Many astronomers travel the world chasing eclipses.

                   If the penumbra passes over you, only part of the sun’s surface blocked out. You see a partial solar eclipse. The sky may dim slightly depending on how much of the sun’s disc covered.

              In some cases, the moon is far enough away in its orbit that the umbra never reaches the Earth at all. In this case, there is no region of totality, and what you see is an annular solar eclipse.

In this eclipse, only a small, ring-like sliver of light seen from the sun’s disc.

Lunar Eclipse

During a lunar eclipse, Earth gets in the way of the sun’s light hitting the moon. That means that during the night, a full moon fades away as Earth’s shadow covers it up.

The moon can also look reddish because Earth’s atmosphere absorbs the other colors while it bends some sunlight toward the moon. Sunlight bending through the atmosphere and absorbing other colors is also why sunsets are orange and red.