equinox, either of the two moments in the year when the Sun is exactly above the Equator and day and night are of equal length; also, either of the two points in the sky where the ecliptic (the Sun’s annual pathway) and the celestial equator intersect.

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. [a]

2024年9月4日 · The equinox marks a significant astronomical event that occurs twice a year, signaling a moment of balance between day and night across the globe. It is when Earth’s tilt perfectly aligns with its orbit around the Sun, creating nearly equal lengths of day and night.

2023年10月19日 · As its name suggests, an equinox indicates equally illuminated hemispheres, with the solar terminator equally dividing Earth from north to south. (The solar terminator is the shadowed line indicating daylight and sunlight on a globe.) A true equinox would indicate 12 hours of both day and night.

During an equinox the tilt of Earth’s axis and Earth’s orbit around the Sun are positioned such that the axis isn’t tilting one hemisphere toward or away from the Sun. Direct sunlight shines on the equator, so the length of day and night is nearly equal for both hemispheres.

2024年3月19日 · Twice a year, day and night are about the same length in both the Southern and Northern Hemispheres. This phenomenon is called an equinox, which comes from the Latin words "aequus" (equal) and...

2024年3月15日 · Every six months, the equinox splits Earth's day almost in half. Here's how it happens—and why people have celebrated it since ancient times.

2024年5月21日 · An equinox is a period in the orbit of a planet in which the planet's orbit and position cause the Sun to pass directly over the equator. In addition to being an astronomy event of note, it also marks a shift in the seasons.

An equinox occurs when the position of the Sun is exactly over the Equator. When this happens, the hours of daylight and the hours of darkness are about equal almost everywhere on Earth. Equinoxes take place twice a year. Autumn, or fall, begins with the autumnal equinox.

2023年3月20日 · equinox: The day on Earth (or another planet) when the period of sunlight and darkness are roughly equal. solstice : These are the days in summer (in June in the northern hemisphere, in December in the southern hemisphere) …