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Usually, a satellite travels either north or south of the Earth's shadow because Earth's axis is not directly perpendicular to a line from the Earth to the Sun at other times. During the equinox, since geostationary satellites are situated above the Equator, they are in Earth's shadow for the longest duration all year.
- Equinox—Close, But Not Quite Equal
- Equal Light
- Imagine A Disk
- A Point at The Center of The Sun
- Atmospheric Bending at Work as Well
Many of us think that an even balance of day to night happens during an equinox. After all, the word translates as “equal night.” So, a little confusion is understandable. But there’s a subtle time difference between an equinoxand an equilux.
“Equilux” is drawn from the Latin terms for equal (equi) and light (lux). So how do we find out which dates fit the description and qualify as truly equal day and night? To measure the day/night split in a 24-hour span, astronomers use common definitions of sunrise and sunset. Simply put, sunrise is defined as when the first bit of the Sun’s disk a...
But why aren’t day and night of equal length at an equinox? To answer that question, it helps to think of the Sun in two different ways—as a disk and as a point. To pinpoint the days of equilux, the Sun is considered a disk, and we measure daytime from the first appearance of the Sun’s disk to the last bit slipping below the horizon.
To calculate an equinox, on the other hand, the Sun is thought of as a single point, set in the center of the disk. An equinox occurs when the subsolar point—the spot on the Earth directly beneath the Sun—crosses the equator, equally straddling the Southern and Northern Hemispheres. On those days, the center point of the Sun indeed rises and sets 1...
Another variable is the fact that the Earth’s atmosphere bends light from the Sun, like a lens. This distortion makes the Sun appear higher than its true position on the horizon. This light bending action, known as atmospheric refraction, means that at most mid-temperate latitudes, sunrise starts earlier and sunset ends later, making the day of an ...
There are only two moments each year when neither pole points toward the Sun, and the Sun lies directly above Earth’s equator. These moments are the equinoxes. The March equinox happens sometime between March 19 and 21. The September equinox occurs sometime between September 21 and 24.
Sep 22, 2021 · September's equinox has arrived today, marking the beginning of astronomical autumn in the Northern Hemisphere, where the nights will get longer than the days until the spring equinox in March...
Sep 20, 2024 · Equinoxes and solstices are two of the most important celestial events on Earth. The equinoxes occur around March 20 and September 22 each year, corresponding to an equal length of day and night. The Earth tilts on its axis so that the sun shines directly over the equator on these days.
The autumn equinox 2022 in the northern hemisphere is on Friday 23 September. The autumn equinox marks the first day of astronomical autumn, and the precise time of the autumn equinox in 2022 will be at 3:04am BST. For the two hemispheres, the equinoxes are opposite each other.
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Jun 21, 2017 · Equinox. In between the solstices are two positions in Earth’s orbit where neither north nor south poles are pointing towards the Sun. These equinoxes happen on or around 21 March (the spring or vernal equinox) and 21 September (the autumn equinox).
