The Moon and the lunar eclipse

Moon: 

Physical Characteristics
Orbit and Motion
Origin and History

The Moon is Earth's only natural satellite. It is one of the largest satellites in the solar system, and its relationship with Earth is so intimate that it plays a pivotal role in our planet's tidal system, climate, and the very origin of life. The Moon's diameter is 3,474 kilometers (about one-quarter of Earth's diameter), its mass is one-eighty-first of Earth's mass, and its average density is 3.34 grams per cubic centimeter, which is less than Earth's (5.51 grams per cubic centimeter)—as a result, the Moon's gravitational pull is one-sixth that of Earth's (for instance, if your weight is 60 kg on Earth, it will be 10 kg on the Moon). The lunar surface is marked by craters (holes), maria (flat plains), and highlands, all formed billions of years ago by meteorite impacts. The Moon has no atmosphere; consequently, the surface temperature fluctuates between 127° Celsius during the day and -173° Celsius at night. This wild swing happens due to direct sunlight and shadow—with no atmosphere to trap the heat. The Moon is primarily made of silicate rock (basalt and anorthosite) and has a small iron-nickel core. As learned from NASA's Apollo missions (1969-1972), the Moon contains helium-3 gas, which could be a source of fusion energy in the future. The Moon orbits Earth once every 27.3 days on average (a sidereal month), and it is in synchronous rotation with Earth—meaning one side of the Moon (the near side) always faces our planet. This is known as "tidal locking": the gravitational pull has equalized the Moon's rotation and orbital period. The Moon's average distance from Earth is 384,400 kilometers. Its orbit is not perfectly circular but rather elliptical (oval-shaped)—with a perigee (closest point) of 363,000 km and an apogee (farthest point) of 405,000 km. The Moon's gravity is the driving force behind ocean tides. Furthermore, the Moon acts as a stabilizer for Earth's axial tilt, which in turn prevents drastic climate shifts. According to the most widely accepted "Giant Impact Hypothesis," the Moon was formed 4.5 billion years ago when a Mars-sized planet (Theia) collided with Earth. Mathematical simulations (computer models) show that the debris ejected from this colossal impact coalesced to form the Moon. During the Apollo 11 mission (1969), Neil Armstrong set foot on the Moon. China's Chang'e-4 (2019) landed on the far side of the Moon. Looking ahead, NASA's Artemis program (post-2025) aims to establish a permanent base on the Moon. The Moon does not produce its own light; it merely reflects sunlight. Its phases (New Moon, First Quarter, Full Moon, Last Quarter) are a result of the Earth-Moon-Sun geometry. It's a matter of spherical geometry: the visible portion is determined by the angular position in the Moon's orbit. For us, the Moon is a "stabilizing force"—the other side of the coin is that life on Earth would have been impossible without it.

Lunar Eclipse: 

Why it occurs?
How it occurs?
What phenomena take place?
What should be done during this time?

A lunar eclipse can be described as a geometric event occurring due to the positions of the Sun, the Earth, and the Moon. Essentially, it occurs when the Earth comes between the Sun and the Moon, and the Earth's shadow falls upon the Moon. This typically happens during a full moon (when the Moon is opposite the Sun). However, an eclipse does not occur every full moon—because the Moon's orbit is inclined at an angle of about 5° to the Earth's orbit (the ecliptic plane). For an eclipse to occur, the Moon must be at or very near the ecliptic plane, which happens twice every six months (eclipse seasons), and an alignment of the Sun, Earth, and Moon (syzygy) is required. An eclipse is possible if the Moon's latitude is within 18.5°. This stems from the combination of the sidereal year (365.24 days) and the lunar cycle. A lunar eclipse is caused by the Earth's shadow. The Earth's shadow is of two types: the Umbra and the Penumbra. The Umbra is the region of total darkness where sunlight is completely blocked, and the Penumbra is the region of partial shadow where some sunlight reaches. In the Penumbral phase, the Moon enters the Earth's penumbral shadow, and the Moon's edge becomes slightly dim. This is not always visible to the naked eye. In the Partial phase, a part of the Moon enters the Umbra, and a section of the Moon turns reddish (blood moon)—because the Earth's atmosphere bends (refracts) sunlight, sending red rays to the Moon (Rayleigh scattering). In the Total phase (if it occurs), the Moon is completely covered by the Umbra and appears red because blue-green light is scattered away, leaving red light predominant, and the Moon cools down (by 10-20° Celsius). Upon exit, it emerges from the Umbra and then the Penumbra. This entire process can take 1 to 3 hours. In a Total Lunar Eclipse, the Moon is completely covered; in a Partial one, it is partially covered; and in a Penumbral one, only a faint shadow is seen. The Saros cycle (18 years 11 days) is used to predict eclipses—it arises from the Moon's nodal precession (the oscillation of its orbit). During a lunar eclipse, the Moon gradually darkens and takes on a reddish hue. It is visible from everywhere on Earth where the Moon is above the horizon. During this time, the Moon's temperature drops, stars appear brighter (because the moonlight diminishes), and animal behavior may change (for instance, birds may fall silent), but this is a logical consequence of the change in light. A lunar eclipse lasts, on average, 2 to 4 hours. Example: The lunar eclipse of March 14, 2025, was a partial one, visible from Asia. The "diamond ring" effect, seen in solar eclipses, is not observed during a total lunar eclipse; instead, gas emissions on the Moon's surface may increase. A lunar eclipse does not emit any harmful rays (such as UV)—it is perfectly safe. The Earth's atmosphere filters all radiation. Therefore, a lunar eclipse can be watched with the naked eye or through a telescope without any special sunglasses. If you are outside during the event, you might feel the chill, so it's a good idea to bundle up in warm clothes. In Hinduism, a lunar eclipse is referred to as "Rahu and Ketu swallowing the moon," and rituals like bathing and worship are performed. So, if you wish to perform worship, you certainly can.