Solar year in the context of "Jewish calendar"

A lunisolar calendar is a calendar in many cultures, that combines monthly lunar cycles with the solar year. As with all calendars which divide the year into months, there is an additional requirement that the year have a whole number of months (Moon cycles). The majority of years have twelve months but every second or third year is an embolismic year, which adds a thirteenth intercalary, embolismic, or leap month.

In contrast to purely lunar calendars such as the Islamic calendar, lunisolar calendars have additional intercalation rules that reset them periodically into a rough agreement with the solar year and thus with the seasons.

A lunar calendar is a calendar based on the monthly cycles of the Moon's phases (synodic months, lunations), in contrast to solar calendars, whose annual cycles are based on the solar year, and lunisolar calendars, whose lunar months are brought into alignment with the solar year through some process of intercalation – such as by insertion of a leap month. The most widely observed lunar calendar is the Islamic calendar. The details of when months begin vary from calendar to calendar, with some using new, full, or crescent moons and others employing detailed calculations.

Since each lunation is approximately 29+1⁄2 days, it is common for the months of a lunar calendar to alternate between 29 and 30 days. Since the period of 12 such lunations, a lunar year, is 354 days, 8 hours, 48 minutes, 34 seconds (354.36707 days), lunar calendars are 11 to 12 days shorter than the solar year. In lunar calendars, which do not make use of lunisolar calendars' intercalation, the lunar months cycle through all the seasons of a solar year over the course of a 33–34 lunar-year cycle (see, e.g., list of Islamic years).

Venus is the second planet from the Sun. It is often called Earth's "twin" or "sister" among the planets of the Solar System for its orbit being the closest to Earth's, both being rocky planets, and having the most similar and nearly equal size, mass, and surface gravity. Venus, though, is significantly different, especially as it has no liquid water, and its atmosphere is far thicker and denser than that of any other rocky body in the Solar System. The atmosphere is composed mostly of carbon dioxide and has a thick cloud layer of sulfuric acid that spans the whole planet. At the mean surface level, the atmosphere reaches a temperature of 737 K (464 °C; 867 °F) and a pressure 92 times greater than Earth's at sea level, turning the lowest layer of the atmosphere into a supercritical fluid. From Earth, Venus is visible as a star-like point of light, appearing brighter than any other natural point of light in the sky, and as an inferior planet always relatively close to the Sun, either as the brightest "morning star" or "evening star".

The orbits of Venus and Earth make the two planets approach each other in synodic periods of 1.6 years. In the course of this, Venus comes closer to Earth than any other planet, in contrast to Mercury which stays closer over the course of an orbit to Earth than any other planet, due to its orbit being closer to the Sun. In interplanetary spaceflight from Earth, Venus is frequently used as a waypoint for gravity assists, offering a faster and more economical route. Venus has no moons and a very slow retrograde rotation about its axis, a result of competing forces of solar tidal locking and differential heating of Venus's massive atmosphere. As a result, a Venusian day is 116.75 Earth days long, about half a Venusian solar year, which is 224.7 Earth days long.

The Hijri era (Arabic: التقويم الهجري, romanized: at-taqwīm al-hijrī) is the calendar era used to record dates in the Islamic world. Its epoch (start point of the era) is the year in which Muhammad and his followers migrated from Mecca to Yathrib (now Medina), in 622 CE. This event, known as the Hijrah, is commemorated in Islam for its role in the founding of the first Muslim community (ummah). Time in this era is measured by two principal calendars: the lunar Hijri calendar (known in the West as the "Islamic calendar") which counts lunar years since the Hijrah and which is used by most Muslims around the world; and the solar Hijri calendar (also known as the "Persian calendar") which counts solar years since the Hijrah and which is used in Iran.

In the West, dates in the lunar Hijri calendar are denoted as AH (Latin: Anno Hegirae) or Hijri year (Arabic: سنة هجرية, romanized: sanat hijriyya, lit. 'in the year of the Hijra') in the style of the Christian/Common (AD/CE) and Jewish eras (AM) and can similarly be placed before (preferably) or after the date. In predominantly Muslim countries, it is also commonly abbreviated H ("Hijra") from its Arabic abbreviation hāʾ (هـ). Years prior to AH 1 are reckoned in English as BH ("Before the Hijra"), which follows the date. Dates in the solar Hijri calendar are denoted as SH. The current year according to the lunar Hijri calendar is AH 1447; according to the solar Hijri calendar the current year is SH 1404. The difference in numbering arises because a lunar year is about eleven days shorter than a solar year.

In the Gregorian calendar, New Year's Day is the first day of the calendar year, 1 January. Most solar calendars, such as the Gregorian and Julian calendars, begin the year regularly at or near the northern winter solstice. In contrast, cultures and religions that observe a lunisolar or lunar calendar celebrate their Lunar New Year at varying points relative to the solar year.

In pre-Christian Rome, under the Julian calendar, the day was dedicated to Janus, god of gateways and beginnings, for whom January is also named. From Roman times until the mid-18th century, the new year was celebrated at various stages and in various parts of Christian Europe on 25 December, on 1 March, on 25 March and on the movable feast of Easter.