A lunar eclipse is an astronomical phenomenon in which the Moon darkens when it passes into the Earth’s shadow. Approximately every six months, during the full moon phase, when the Moon’s orbital plane is closest to the Earth’s orbital plane, such an alignment takes place.
Only when the Sun, Earth, and Moon are exactly or almost aligned can there be a lunar eclipse. Only when the Moon is close to one of its orbital nodes during a full moon can this alignment occur. The Moon’s proximity to the node at the moment of the eclipse determines its kind and length.
When the Earth completely blocks direct sunlight from reaching the Moon’s surface, it causes a “deep eclipse” in which the Moon takes on a reddish hue. This is because only light that has been refracted by the Earth’s atmosphere is reflected from the lunar surface. Sunrises and sunsets are more orange than during the day because of the Rayleigh scattering of blue light, which gives this light its reddish appearance.
A lunar eclipse may be seen from anyplace on Earth’s night side, unlike a solar eclipse, which can only be seen from a very limited portion of the planet. Because of the Moon’s smaller shadow, a total lunar eclipse may last up to almost two hours, whereas a total solar eclipse only lasts a few minutes at any one location. In contrast to solar eclipses, lunar eclipses may be safely observed without the need for extra safety measures or eye protection.
Types of lunar eclipse
There are two separate components to Earth’s shadow, the penumbra and the umbra. Earth completely blocks out direct sun light in the shadow’s middle portion, known as the umbra. In the lunar sky, however, the Sun’s diameter seems to be only 25% of Earth’s, therefore the planet only partially blocks direct sunlight in the penumbra, or outer half of the shadow.
Penumbral lunar eclipse
When the Moon’s near side partially or completely enters the Earth’s penumbra, it is known as a penumbral lunar eclipse. No part of the moon is in the Earth’s umbra during this occurrence, meaning that on all or a part of the Moon’s surface facing Earth, the sun is partially hidden. The penumbra creates a modest darkening of the lunar surface, which is only apparent to the naked eye after the bulk of the Moon’s diameter has plunged into Earth’s penumbra. A total penumbral lunar eclipse is a unique kind of penumbral eclipse in which the entire Moon is entirely within Earth’s penumbra. The area of the Moon nearest to the umbra may look somewhat darker than the rest of the lunar disk during rare total penumbral eclipses.
Partial lunar eclipse
A partial lunar eclipse is when the Moon’s near side partially enters the Earth’s umbra , whereas a total lunar eclipse is when the Moon completely enters the Earth’s umbra. The Moon is in the penumbra of the Earth during this event, and the Moon is in the umbra of the Earth during this event. Since the Moon’s typical orbital speed is little over its diameter per hour, or 1.03 km/s (2,300 mph), totality may endure for over 107 minutes. The whole period, however, between the Moon’s limb’s initial and final interactions with Earth’s shadow is far longer and may reach 236 minutes.
Total lunar eclipse
A total lunar eclipse happens when the Moon’s near side completely enters the Earth’s umbral shadow. The lunar limb, which is the curving part of the Moon that is still receiving direct sunlight, will be so brilliant that the remainder of the Moon will look rather dark just before full entrance. The Moon will become more or less evenly bright over its surface as soon as it undergoes a full eclipse, allowing the surrounding stars to be seen. Later, the entire disk will be veiled once more as sunlight strikes the Moon’s opposing limb. The edges of full moons typically appear brighter than the rest of the lunar surface because, when viewed from Earth, the brightness of a lunar limb is typically greater than that of the rest of the surface due to reflections from the numerous surface irregularities within the limb, sunlight striking these irregularities is always reflected back in greater quantities than that striking more central parts. Velvet fabric over a convex curved surface has a similar effect, appearing darkest near the curve’s center to the spectator. When viewed in opposition to the Sun, it will apply to any planetary body with a cratered surface and little to no atmosphere, such as Mercury.
Central lunar eclipse
The Moon travels close to and into the center of Earth’s shadow, making contact with the antisolar point, during a central lunar eclipse, which is a type of total lunar eclipse. Lunar eclipses of this kind are very uncommon.
The length of an eclipse can be influenced by the Moon’s relative distance from Earth at the moment of the eclipse. The Moon’s orbital speed is slowest when it is close to apogee, which is the furthest point from Earth in its orbit. Changes in the Moon’s orbital distance do not significantly reduce the diameter of Earth’s umbra. Therefore, the time of totality will be extended if a completely obscured Moon coincides with apogee.
Selenelion
When the Sun and an eclipsed Moon can be seen simultaneously, it is termed a selenelion or selenehelion, also known as a horizontal eclipse. The occurrence is only seen shortly before sunset or shortly after sunrise, when both bodies will be visible at roughly opposite locations in the sky, barely over opposite horizons. Every complete lunar eclipse has a selenelion, which is an experience of the observer rather than a happening on the planet apart from the eclipse. It will usually be visible to spectators on Earth who are on high mountain ridges experiencing false dawn or false sunset at the same time as a complete moon eclipse. Because of atmospheric refraction, the Moon and the Sun look higher (more central) in the sky than their actual geometric planetary positions, even though they are both fully within the Earth’s umbra during selenelion.
Timing
The so-called “contacts” (moments of contact with Earth’s shadow) of the moon govern when total lunar eclipses occur.
1. P1 (First Contact) – The penumbral eclipse starts. The Moon’s outer limb is touched by Earth’s penumbra.
2. U1 (contact) – The Moon’s outer limb is touched by Earth’s umbra.
3. U2 (Third contact) – Total eclipse commencement. The whole surface of the Moon lies inside Earth’s orbit.
4. Greatest eclipse – The greatest eclipse is the total eclipse’s highest point. The Moon is closest to the Earth’s umbra’s core.
5. U3 (fourth contact) – Total eclipse ends at the fourth contact. The outer limb of the Moon leaves the Earth’s shadow.
6. U4 (Fifth contact) – Partial eclipse ends. The moon’s surface is where the Earth’s umbra departs.
7. P4 (sixth contact) – Penumbral eclipse ends. The penumbra of the Earth no longer touches the Moon.
Danjon Scale
André Danjon created the Danjon scale, which is used to rate the total darkness of lunar eclipses.
1) L = 0 – Eclipse that is very dark. The moon is nearly undetectable, particularly at mid-totality.
2) L = 1 – A dark eclipse with a gray or brownish hue. Only with difficulty can details be distinguished.
3) L = 2 – An eclipse with a deep red or rust hue. The umbra’s outside border is comparatively light, while the center shadow is quite black.
4) L = 3 – Eclipse in brick-red. The rim of an umbral shadow is often brilliant or golden.
5) L = 4 – An extremely vivid orange or copper-red eclipse. The margin of the bluish umbral shadow is quite vivid.
Lunar versus solar eclipse
A solar eclipse and a lunar eclipse are frequently confused. Although the Sun, Earth, and Moon interact in both, the ways in which they do so varies greatly.
Because of the refraction of sunlight into the shadow cone by Earth’s atmosphere, the Moon does not entirely darken as it goes through the umbra; in the absence of Earth’s atmosphere, the Moon would be completely black during the eclipse. [16] Sunlight must travel through a lengthy and thick layer of Earth’s atmosphere before it can reach the Moon, where it is dispersed, giving it its reddish hue. By the time the light beams have passed through the atmosphere, the longer wavelengths are more prevalent because the air molecules and tiny particles are more likely to scatter shorter wavelengths. This ensuing light is seen as red by human eyesight. This is the same phenomenon that gives the sky a crimson hue at sunrises and sunsets. Another approach to imagine this situation is to consider that the Sun would appear to be setting (or rising) behind Earth as viewed from the Moon.
Conclusion
shadow, producing breathtaking visual effects that may be seen from our planet’s night side. Lunar eclipses may be safely observed with the unaided eye from any point with a clear sky, unlike solar eclipses, which need protective gear and are only viewable in certain areas.
varied lunar eclipses—partial, total, penumbral, and central—offer varied levels of spectacle. Because of air refraction, complete eclipses create the dramatic “Blood Moon” effect. A precise series of encounters with Earth’s shadow determines the time of these occurrences, and the Danjon Scale is used to categorize the eclipse’s darkness.