Ecliptic in the context of Fire sign

Astronomy in China has a long history stretching from the Shang dynasty, being refined over a period of more than 3,000 years. The ancient Chinese people have identified stars from 1300 BCE, as Chinese star names later categorized in the twenty-eight mansions have been found on oracle bones unearthed at Anyang, dating back to the mid-Shang dynasty. The core of the "mansion" (宿 xiù) system also took shape around this period, by the time of King Wu Ding (1250–1192 BCE).

Detailed records of astronomical observations began during the Warring States period (fourth century BCE). They flourished during the Han period (202 BCE – 220 CE) and subsequent dynasties with the publication of star catalogues. Chinese astronomy was equatorial, centered on close observation of circumpolar stars, and was based on different principles from those in traditional Western astronomy, where heliacal risings and settings of zodiac constellations formed the basic ecliptic framework. Joseph Needham has described the ancient Chinese as the most persistent and accurate observers of celestial phenomena anywhere in the world before the Islamic astronomers.

Weather refers to the state of the Earth's atmosphere at a specific place and time, typically described in terms of temperature, humidity, cloud cover, and stability. On Earth, most weather phenomena occur in the lowest layer of the planet's atmosphere, the troposphere, just below the stratosphere. Weather refers to day-to-day temperature, precipitation, and other atmospheric conditions, whereas climate is the term for the averaging of atmospheric conditions over longer periods of time. When used without qualification, "weather" is generally understood to mean the weather of Earth.

Weather is driven by air pressure, temperature, and moisture differences between one place and another. These differences can occur due to the Sun's angle at any particular spot, which varies with latitude. The strong temperature contrast between polar and tropical air gives rise to the largest scale atmospheric circulations: the Hadley cell, the Ferrel cell, the polar cell, and the jet stream. Weather systems in the middle latitudes, such as extratropical cyclones, are caused by instabilities of the jet streamflow. Because Earth's axis is tilted relative to its orbital plane (called the ecliptic), sunlight is incident at different angles at different times of the year. On Earth's surface, temperatures usually range ±40 °C (−40 °F to 104 °F) annually. Over thousands of years, changes in Earth's orbit can affect the amount and distribution of solar energy received by Earth, thus influencing long-term climate and global climate change.

The Southern Hemisphere is the half (hemisphere) of Earth that is south of the equator. It contains all or part of five continents (the whole of Antarctica, the whole of Australia, about 90% of South America, about one-third of Africa, and some islands off the continental mainland of Asia) and four oceans (the whole Southern Ocean, the majority of the Indian Ocean, the South Atlantic Ocean, and the South Pacific Ocean), as well as New Zealand and most of the Pacific Islands in Oceania. Its surface is 80.9% water, compared with 60.7% water in the Northern Hemisphere, and it contains 32.7% of Earth's land. More than 850 million people live in the Southern Hemisphere, representing around 10–12% of the total global human population.

Owing to the tilt of Earth's rotation relative to the Sun and the ecliptic plane, summer is from December to February (inclusive) and winter is from June to August (inclusive). September 22 or 23 is the vernal equinox and March 20 or 21 is the autumnal equinox. The South Pole is in the centre of the southern hemispherical region.

In astronomy, axial precession is a gravity-induced, slow, and continuous change in the orientation of an astronomical body's rotational axis. In the absence of precession, the astronomical body's orbit would show axial parallelism. In particular, axial precession can refer to the gradual shift in the orientation of Earth's axis of rotation in a cycle of approximately 26,000 years. This is similar to the precession of a spinning top, with the axis tracing out a pair of cones joined at their apices. The term "precession" typically refers only to this largest part of the motion; other changes in the alignment of Earth's axis—nutation and polar motion—are much smaller in magnitude.

Earth's precession was historically called the precession of the equinoxes, because the equinoxes moved westward along the ecliptic relative to the fixed stars, opposite to the yearly motion of the Sun along the ecliptic. Historically, the discovery of the precession of the equinoxes is usually attributed in the West to the 2nd-century-BC astronomer Hipparchus. With improvements in the ability to calculate the gravitational force between planets during the first half of the nineteenth century, it was recognized that the ecliptic itself moved slightly, which was named planetary precession, as early as 1863, while the dominant component was named lunisolar precession. Their combination was named general precession, instead of precession of the equinoxes.

Horoscopic astrology is a form of astrology that uses a horoscope, a visual representation of the heavens, for a specific moment in time to interpret the purported meaning behind the alignment of the planets at that moment. The idea is that the placement of the planets at any given moment in time supposedly reflects the nature of that moment and especially anything that is born then, and proponents claim that this can be analyzed using the chart and a variety of rules for interpreting the "language" or symbols therein.

One of the defining characteristics of this form of astrology that makes it distinct from other traditions is the computation of the degree of the Eastern horizon rising against the backdrop of the ecliptic at the specific moment under examination, known as the ascendant. As a general rule, any system of astrology that does not use the ascendant does not fall under the category of horoscopic astrology, although there are some exceptions.

The zodiac is a belt-shaped region of the sky that extends approximately 8° north and south celestial latitude of the ecliptic – the apparent path of the Sun across the celestial sphere over the course of the year. Within this zodiac belt appear the Moon and the brightest planets, along their orbital planes. The zodiac is divided along the ecliptic into 12 equal parts, called "signs", each occupying 30° of celestial longitude. These signs roughly correspond to the astronomical constellations with the following modern names: Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, and Pisces.

The signs have been used to determine the time of the year by identifying each sign with the days of the year the Sun is in the respective sign. In Western astrology, and formerly astronomy, the time of each sign is associated with different attributes. The zodiacal system and its angular measurement in 360 sexagesimal degree (°) originated with Babylonian astronomy during the 1st millennium BC, probably during the Achaemenid Empire. It was communicated into Greek astronomy by the 2nd century BC, as well as into developing the Hindu zodiac. Due to the precession of the equinoxes, the time of year that the Sun is in a given constellation has changed since Babylonian times, and the point of March equinox has moved from Aries into Pisces.

Sagittarius A*, abbreviated as Sgr A* (/ˈsædʒ ˈeɪ stɑːr/ SADGE-AY-star), is the supermassive black hole at the Galactic Center of the Milky Way. Viewed from Earth, it is located near the border of the constellations Sagittarius and Scorpius, about 5.6° south of the ecliptic, visually close to the Butterfly Cluster (M6) and Lambda Scorpii. Sagittarius A* is a bright and very compact astronomical radio source.

In May 2022, astronomers released the first image of the accretion disk around the event horizon of Sagittarius A*, using the Event Horizon Telescope, a world-wide network of radio observatories. This is the second confirmed image of a black hole, after Messier 87's supermassive black hole in 2019. The black hole itself is not seen; as light is incapable of escaping the immense gravitational force of a black hole, only nearby objects whose behavior is influenced by the black hole can be observed. The observed radio and infrared energy emanates from gas and dust heated to millions of degrees while falling into the black hole.

The scattered disc (or scattered disk) is a distant circumstellar disc in the Solar System that is sparsely populated by icy small Solar System bodies, which are a subset of the broader family of trans-Neptunian objects. The scattered-disc objects (SDOs) have orbital eccentricities ranging as high as 0.8, inclinations as high as 40°, and perihelia greater than 30 astronomical units (4.5×10 km; 2.8×10 mi). These extreme orbits are thought to be the result of gravitational "scattering" by the gas giants, and the objects continue to be subject to perturbation by the planet Neptune.

Although the closest scattered-disc objects approach the Sun at about 30–35 AU, their orbits can extend well beyond 100 AU. This makes scattered disc objects among the coldest and most distant known objects in the Solar System. The innermost portion of the scattered disc overlaps with a torus-shaped region of orbiting objects traditionally called the Kuiper belt, but its outer limits reach much farther away from the Sun and farther above and below the ecliptic than the Kuiper belt proper.

The Oort cloud (pronounced /ɔːrt/ ORT or /ʊərt/ OORT), sometimes called the Öpik–Oort cloud, is theorized to be a cloud of billions of icy planetesimals surrounding the Sun at distances ranging from 2,000 to 200,000 AU (0.03 to 3.2 light-years). The cloud was proposed in 1950 by the Dutch astronomer Jan Oort, in whose honor the idea was named. Oort proposed that the bodies in this cloud replenish and keep constant the number of long-period comets entering the inner Solar System—where they are eventually consumed and destroyed during close approaches to the Sun.

The cloud is thought to encompass two regions: a disc-shaped inner Oort cloud aligned with the solar ecliptic (also called its Hills cloud) and a spherical outer Oort cloud enclosing the entire Solar System. Both regions lie well beyond the heliosphere and are in interstellar space. The innermost portion of the Oort cloud is more than a thousand times as far from the Sun as the Kuiper belt, the scattered disc and the detached objects—three nearer reservoirs of trans-Neptunian objects.

Right ascension (abbreviated RA; symbol α) is the angular distance of a particular point measured eastward along the celestial equator from the Sun at the March equinox to the (hour circle of the) point in question above the Earth. When paired with declination, these astronomical coordinates specify the location of a point on the celestial sphere in the equatorial coordinate system.

An old term, right ascension (Latin: ascensio recta) refers to the ascension, or the point on the celestial equator that rises with any celestial object as seen from Earth's equator, where the celestial equator intersects the horizon at a right angle. It contrasts with oblique ascension, the point on the celestial equator that rises with any celestial object as seen from most latitudes on Earth, where the celestial equator intersects the horizon at an oblique angle.

In astronomy, declination (abbreviated dec; symbol δ) is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle. The declination angle is measured north (positive) or south (negative) of the celestial equator, along the hour circle passing through the point in question.

The root of the word declination (Latin, declinatio) means "a bending away" or "a bending down". It comes from the same root as the words incline ("bend forward") and recline ("bend backward").

In astronomy, a conjunction occurs when two astronomical objects or spacecraft appear to be close to each other in the sky. This means they have either the same right ascension or the same ecliptic longitude, usually as observed from Earth.

When two objects always appear close to the ecliptic—such as two planets, the Moon and a planet, or the Sun and a planet—this fact implies an apparent close approach between the objects as seen in the sky. A related word, appulse, is the minimum apparent separation in the sky of two astronomical objects.

Chinese star names (Chinese: 星名, xīng míng) are named according to ancient Chinese astronomy and astrology. The sky is divided into star mansions (星宿, xīng xiù, also translated as "lodges") and asterisms (星官, xīng guān). The ecliptic is divided into four sectors that are associated with the Four Symbols, guardians in Chinese mythology, and further into 28 mansions. Stars around the north celestial pole are grouped into three enclosures (垣, yuán). The system of 283 asterisms under the Three Enclosures and Twenty-Eight Mansions was established by Chen Zhuo of the Three Kingdoms period, who synthesized ancient constellations and the asterisms created by early astronomers Shi Shen, Gan De and Wuxian. Since the Han and Jin dynasties, stars have been given reference numbers within their asterisms in a system similar to the Bayer or Flamsteed designations, so that individual stars can be identified. For example, Deneb (α Cyg) is referred to as 天津四 (Tiān Jīn Sì, the Fourth Star of Celestial Ford).

In the Qing dynasty, Chinese knowledge of the sky was improved by the arrival of European star charts. Yixiang Kaocheng, compiled in mid-18th century by then deputy Minister of Rites Ignaz Kögler, expanded the star catalogue to more than 3000 stars. The newly added stars (增星, zēng xīng) were named as 增一 (zēng yī, 1st added star), 增二 (zēng èr, 2nd added star) etc. For example, γ Cephei is referred to as 少衛增八 (Shào Wèi Zēng Bā, 8th Added Star of Second Imperial Guard). Some stars may have been assigned more than one name due to the inaccuracies of traditional star charts.

A solar term (or jiéqì, simplified Chinese: 节气; traditional Chinese: 節氣) is any of twenty-four moments in traditional Chinese lunisolar calendars that matches a particular astronomical event and signifies some natural phenomenon. The points are spaced 15° apart along the ecliptic and are used by lunisolar calendars to stay synchronized with the seasons, which is crucial for agrarian societies. The solar terms are also used to calculate intercalary months; which month is repeated depends on the position of the sun at the time.

According to the Book of Documents, the first determined term was Dongzhi (Winter Solstice) by Dan, the Duke of Zhou, while he was trying to locate the geological center of the Western Zhou dynasty, by measuring the length of the sun's shadow on an ancient type of sundial called tǔguī [ja] (土圭). Then four terms of seasons were set, which were soon evolved as eight terms; not until the Taichu Calendar of 104 BC were all twenty-four solar terms officially included in the Chinese calendar.

A sidereal year (/saɪˈdɪəri.əl/, US also /sɪ-/; from Latin sidus 'asterism, star'), also called a sidereal orbital period, is the time that Earth or another planetary body takes to orbit the Sun once with respect to the fixed stars.

Hence, for Earth, it is also the time taken for the Sun to return to the same position relative to Earth with respect to the fixed stars after apparently travelling once around the ecliptic.

The celestial equator is the great circle of the imaginary celestial sphere on the same plane as the equator of Earth. By extension, it is also a plane of reference in the equatorial coordinate system. Due to the Earth's axial tilt, the celestial equator is currently inclined by about 23.44° with respect to the ecliptic (the plane of Earth's orbit), but has varied from about 22.0° to 24.5° over the past 5 million years due to Milankovitch cycles and perturbation from other planets.

An observer standing on the Earth's equator visualizes the celestial equator as a semicircle passing through the zenith, the point directly overhead. As the observer moves north (or south), the celestial equator tilts towards the opposite horizon. The celestial equator is defined to be infinitely distant (since it is on the celestial sphere); thus, the ends of the semicircle always intersect the horizon due east and due west, regardless of the observer's position on the Earth. At the poles, the celestial equator coincides with the astronomical horizon. At all latitudes, the celestial equator is a uniform arc or circle because the observer is only finitely far from the plane of the celestial equator, but infinitely far from the celestial equator itself.

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.