Lunar node in the context of "Solar eclipse of August 11, 1999"

A lunar eclipse, also called a blood moon, is an astronomical event that occurs when the Moon orbits through Earth's shadow.‍‍ Lunar eclipses occur during eclipse season, when the Moon's orbital plane is approximately in line with Earth and the Sun. The type and length of a lunar eclipse depend on the Moon's proximity to the lunar node.‍‍ In contrast with illusive and short-lasting solar eclipses, lunar eclipses can be observed from anywhere on the night side of Earth and often last for an hour or longer. Lunar eclipses are safe to observe without eye protection.

Lunar eclipses are notable for causing the Moon to appear orange or red. This occurs when the Moon passes through the Earth's umbra, necessitating any sunlight that reaches the Moon to first pass through the Earth's atmosphere. The resulting Rayleigh scattering removes high-wavelength colors such as violet and blue from the incoming light before it reflects off the lunar surface and is observed on Earth.

In astronomy and celestial navigation, an ephemeris (/ɪˈfɛmərɪs/; pl. ephemerides /ˌɛfəˈmɛrɪˌdiːz/; from Latin ephemeris 'diary', from Ancient Greek ἐφημερίς (ephēmerís) 'diary, journal') is a book with tables that gives the trajectory of naturally occurring astronomical objects and artificial satellites in the sky, i.e., the position (and possibly velocity) over time. Historically, positions were given as printed tables of values, given at regular intervals of date and time. The calculation of these tables was one of the first applications of mechanical computers. Modern ephemerides are often provided in electronic form. However, printed ephemerides are still produced, as they are useful when computational devices are not available.

The astronomical position calculated from an ephemeris is often given in the spherical polar coordinate system of right ascension and declination, together with the distance from the origin if applicable. Some of the astronomical phenomena of interest to astronomers are eclipses, apparent retrograde motion/planetary stations, planetary ingresses, sidereal time, positions for the mean and true nodes of the moon, the phases of the Moon, and the positions of minor celestial bodies such as Chiron.

A total solar eclipse occurred at the Moon's ascending node of orbit on Tuesday, August 18, 1868 (also known as "The King of Siam's eclipse"), with a magnitude of 1.0756. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide. Occurring about 6.5 days after perigee (on August 17, 1868, at 22:35 UTC), the Moon's apparent diameter was larger.

The path of totality was visible from parts of modern-day Ethiopia, Eritrea, Djibouti, Yemen, India, the Andaman and Nicobar Islands, Myanmar, Thailand, Cambodia, Vietnam, Malaysia, Brunei, Indonesia, and Papua New Guinea. A partial solar eclipse was also visible for parts of East Africa, the Middle East, Central Asia, South Asia, Southeast Asia, Australia, and western Oceania.

A total lunar eclipse occurred at the Moon’s ascending node of orbit on Thursday, October 28, 2004, with an umbral magnitude of 1.3100. A lunar eclipse occurs when the Moon moves into the Earth's shadow, causing the Moon to be darkened. A total lunar eclipse occurs when the Moon's near side entirely passes into the Earth's umbral shadow. Unlike a solar eclipse, which can only be viewed from a relatively small area of the world, a lunar eclipse may be viewed from anywhere on the night side of Earth. A total lunar eclipse can last up to nearly two hours, while a total solar eclipse lasts only a few minutes at any given place, because the Moon's shadow is smaller. Occurring about 5.4 days before apogee (on November 2, 2004, at 13:10 UTC), the Moon's apparent diameter was smaller.

This lunar eclipse is the last of a tetrad, with four total lunar eclipses in series, the others being on May 16, 2003; November 9, 2004; and May 4, 2004.

A total lunar eclipse occurred at the Moon’s ascending node of orbit on Tuesday, April 15, 2014, with an umbral magnitude of 1.2918. A lunar eclipse occurs when the Moon moves into the Earth's shadow, causing the Moon to be darkened. A total lunar eclipse occurs when the Moon's near side entirely passes into the Earth's umbral shadow. Unlike a solar eclipse, which can only be viewed from a relatively small area of the world, a lunar eclipse may be viewed from anywhere on the night side of Earth. A total lunar eclipse can last up to nearly two hours, while a total solar eclipse lasts only a few minutes at any given place, because the Moon's shadow is smaller. The Moon's apparent diameter was near the average diameter because it occurred 6.9 days after apogee (on April 8, 2014, at 10:50 UTC) and 7.6 days before perigee (on April 22, 2014, at 20:20 UTC).

This lunar eclipse is the first of a tetrad, with four total lunar eclipses in series, the others being on October 8, 2014; April 4, 2015; and September 28, 2015.

An eclipse season is a period of roughly 1 month, occurring roughly every six months, when the orbits of the Earth, Sun, and Moon align such that solar and lunar eclipses occur. Eclipse seasons are the result of the axial parallelism of the Moon's orbital plane (tilted five degrees to the Earth's orbital plane), just as Earth's weather seasons are the result of the axial parallelism of Earth's tilted axis as it orbits around the Sun. During the season, the "lunar nodes" – the line where the Moon's orbital plane intersects with the Earth's orbital plane – align with the Sun and Earth, such that a solar eclipse is formed during the new moon phase and a lunar eclipse is formed during the full moon phase.

Only two (or occasionally three) eclipse seasons occur during each year, and each season lasts about 35 days and repeats just short of six months (173 days) later, thus two full eclipse seasons always occur each year. Either two or three eclipses happen each eclipse season. During the eclipse season, the Moon is at a low ecliptic latitude (less than around 1.5° north or south), hence the Sun, Moon, and Earth become aligned straightly enough (in syzygy) for an eclipse to occur. Eclipse seasons should occur 38 times within a saros period (6,585.3 days).

A total solar eclipse occurred at the Moon's descending node of orbit between Saturday, July 21 and Sunday, July 22, 1990, with a magnitude of 1.0391. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. A total solar eclipse occurs when the Moon's apparent diameter is larger than the Sun's, blocking all direct sunlight, turning day into darkness. Totality occurs in a narrow path across Earth's surface, with the partial solar eclipse visible over a surrounding region thousands of kilometres wide. Occurring 2.7 days after perigee (on July 19, 1990, at 12:20 UTC), the Moon's apparent diameter was larger.

Totality was visible in southern Finland including its capital city Helsinki, the Soviet Union (including today's northern Estonia and northern Russia), and eastern Andreanof Islands and Amukta of Alaska. A partial eclipse was visible for parts of Eastern Europe, North Asia, Alaska, western Canada, the western United States, and Hawaii.