Evening is the period of a day that begins at the end of daylight and overlaps with the beginning of night. [1] It generally indicates the period of time when the sun is close to the horizon and comprises the periods of civil, nautical and astronomical twilight. The exact times when evening begins and ends are subjective and depend on location and time of year. It may be used colloquially to include the last waning daytime shortly before sunset. [2]
The word is derived from the Old English ǣfnung, meaning 'the coming of evening, sunset, time around sunset', which originated from æfnian, meaning "become evening, grow toward evening". The Old English æfnian originated from æfen (eve), which meant "the time between sunset and darkness", and was synonymous with even (Old English æfen), which meant the end of the day. The use of "evening" dates from the mid 15th century. [3]
The Encyclopædia Britannica defines evening as varying according to daylight and lifestyle, but says that many people consider it to begin at 5 p.m. [4]
In a social context, the Oxford English Dictionary defines evening as "the time from about 6 p.m., or sunset if earlier". [1]
As such there is no fixed consensus on when the period of evening starts.
Despite the less favorable lighting conditions for optical astronomy, evening can be useful for observing objects orbiting close to the Sun. Evening (and morning) serves as the optimum time for viewing the inferior planets Venus and Mercury. [5] It is a popular time to hunt for comets, as their tails grow more prominent as these objects draw closer to the Sun. [6] The evening (and morning) twilight is used to search for near-Earth asteroids that orbit inside the orbit of the Earth. [7] In mid-latitudes, spring evenings around the time of the equinox―that is, the March one in the Northern Hemisphere and the September equinox to the south of the equator―are favorable for viewing the zodiacal light. [8] [9]
A day is the time period of a full rotation of the Earth with respect to the Sun. On average, this is 24 hours. As a day passes at a given location it experiences morning, noon, afternoon, evening, and night. This daily cycle drives circadian rhythms in many organisms, which are vital to many life processes.
A solar equinox is a moment in time when the Sun crosses the Earth's equator, which is to say, appears directly above the equator, rather than north or south of the equator. On the day of the equinox, the Sun appears to rise "due east" and set "due west". This occurs twice each year, around 20 March and 23 September.
The zodiac is a belt-shaped region of the sky that extends approximately 8° north and south of the ecliptic, the apparent path of the Sun across the celestial sphere over the course of the year. Also 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 ("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.
Zodiacal light is a faint glow of diffuse light in the sky scattered by interplanetary dust, particularly a zodiacal cloud, along the ecliptic, and therefore the zodiac. It is mostly only visible in very dark conditions across the night sky along the whole ecliptic as the zodiacal band, backscattered slightly brighter from an oval area of the band directly opposite to the light source as the gegenschein and brightest as a triangle-shaped area at the horizon around the light source as false dawn, mostly just before or after the Sun rises or sets.
Sidereal time is a system of timekeeping used especially by astronomers. Using sidereal time and the celestial coordinate system, it is easy to locate the positions of celestial objects in the night sky. Sidereal time is a "time scale that is based on Earth's rate of rotation measured relative to the fixed stars".
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.
In astronomy, a planet's elongation is the angular separation between the Sun and the planet, with Earth as the reference point. The greatest elongation of a given inferior planet occurs when this planet's position, in its orbital path around the Sun, is at tangent to the observer on Earth. Since an inferior planet is well within the area of Earth's orbit around the Sun, observation of its elongation should not pose that much a challenge. When a planet is at its greatest elongation, it appears farthest from the Sun as viewed from Earth, so its apparition is also best at that point.
The heliacal rising of a star or a planet occurs annually when it first becomes visible above the eastern horizon at dawn just before sunrise after a complete orbit of the Earth around the Sun. Historically, the most important such rising is that of Sirius, which was an important feature of the Egyptian calendar and astronomical development. The rising of the Pleiades heralded the start of the Ancient Greek sailing season, using celestial navigation, as well as the farming season. Helical rising is one of several types of risings and settings, mostly they are grouped into morning and evening risings and settings of objects in the sky. Culmination in the evening and then morning is set apart by half a year, while on the other hand risings and settings in the evenings and the mornings are only at the equator set apart by half a year.
Dawn is the time that marks the beginning of twilight before sunrise. It is recognized by the appearance of indirect sunlight being scattered in Earth's atmosphere, when the centre of the Sun's disc has reached 18° below the observer's horizon. This morning twilight period will last until sunrise, when direct sunlight outshines the diffused light.
Twilight is light produced by sunlight scattering in the upper atmosphere, when the Sun is below the horizon, which illuminates the lower atmosphere and the Earth's surface. The word twilight can also refer to the periods of time when this illumination occurs.
1566 Icarus is a large near-Earth object of the Apollo group and the lowest numbered potentially hazardous asteroid. It has an extremely eccentric orbit (0.83) and measures approximately 1.4 km (0.87 mi) in diameter. In 1968, it became the first asteroid ever observed by radar. Its orbit brings it closer to the Sun than Mercury and further out than the orbit of Mars, which also makes it a Mercury-, Venus-, and Mars-crossing asteroid. This stony asteroid and relatively fast rotator with a period of 2.27 hours was discovered on 27 June 1949, by German astronomer Walter Baade at the Palomar Observatory in California. It was named after the mythological Icarus.
Morning is the period from sunrise to noon. It is preceded by the twilight period of dawn. There are no exact times for when morning begins because it can vary according to one's lifestyle and the hours of daylight at each time of year. However, morning strictly ends at noon, which is when afternoon starts.
Atira asteroids or Apohele asteroids, also known as interior-Earth objects (IEOs), are Near-Earth objects whose orbits are entirely confined within Earth's orbit; that is, their orbit has an aphelion smaller than Earth's perihelion, which is 0.983 astronomical units (AU). Atira asteroids are by far the least numerous group of near-Earth objects, compared to the more populous Aten, Apollo and Amor asteroids.
The night sky is the nighttime appearance of celestial objects like stars, planets, and the Moon, which are visible in a clear sky between sunset and sunrise, when the Sun is below the horizon.
Many astronomical phenomena viewed from the planet Mars are the same as or similar to those seen from Earth; but some are quite different. For example, because the atmosphere of Mars does not contain an ozone layer, it is also possible to make UV observations from the surface of Mars.
Daytime as observed on Earth is the period of the day during which a given location experiences natural illumination from direct sunlight. Daytime occurs when the Sun appears above the local horizon, that is, anywhere on the globe's hemisphere facing the Sun. In direct sunlight the movement of the sun can be recorded and observed using a sundial that casts a shadow that slowly moves during the day. Other planets and natural satellites that rotate relative to a luminous primary body, such as a local star, also experience daytime, but this article primarily discusses daytime on Earth.
Discovery and exploration of the Solar System is observation, visitation, and increase in knowledge and understanding of Earth's "cosmic neighborhood". This includes the Sun, Earth and the Moon, the major planets Mercury, Venus, Mars, Jupiter, Saturn, Uranus, and Neptune, their satellites, as well as smaller bodies including comets, asteroids, and dust.
This glossary of astronomy is a list of definitions of terms and concepts relevant to astronomy and cosmology, their sub-disciplines, and related fields. Astronomy is concerned with the study of celestial objects and phenomena that originate outside the atmosphere of Earth. The field of astronomy features an extensive vocabulary and a significant amount of jargon.
Venus has an orbit with a semi-major axis of 0.723 au, and an eccentricity of 0.007. The low eccentricity and comparatively small size of its orbit give Venus the least range in distance between perihelion and aphelion of the planets: 1.46 million km. The planet orbits the Sun once every 225 days and travels 4.54 au in doing so, giving an average orbital speed of 35 km/s (78,000 mph).
594913 ꞌAylóꞌchaxnim (provisional designation 2020 AV2) is a large near-Earth asteroid discovered by the Zwicky Transient Facility on 4 January 2020. It is the first asteroid discovered to have an orbit completely within Venus's orbit, and is thus the first and only known member of the eponymous ꞌAylóꞌchaxnim (informally named Vatira before its discovery) population of Atira-class asteroids. ꞌAylóꞌchaxnim has the smallest known aphelion and third-smallest known semi-major axis among all asteroids. With an absolute magnitude approximately 16.2, the asteroid is expected to be larger than 1 km in diameter.
The close of day, esp. the time from about 6 p.m., or sunset if earlier, to bedtime; the period between afternoon and night.
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