In the year 2023, when does the first day of Autumnal equinox 2023?
In more careful phrasing, the answer lies in the fact that on Saturday, September 23, at 2:50 AM EDT (0650 GMT), the astronomical autumn begins in the northern hemisphere, while spring commences in the south. Currently, the Sun is retreating towards the south, having spent the last six months shining directly over the northern half of our planet.
Consequently, at the official start of autumn, aboard a ship in the Lakshadweep Sea, located on the equator at a latitude of 170 miles (275 kilometers) northeast of Addu City in the Maldives, the Sun will be visible directly overhead.
We refer to this phenomenon as the “equinox” in Latin, which alludes to the fact that, worldwide, the duration of day and night is equal. However, this is not necessarily the case.
Not quite so
The definition of an equinox as a time when day and night are equal is a convenient oversimplification. For one thing, it only considers night as occurring when the Sun is below the horizon and entirely disregards twilight.
If there were no atmospheric refraction, and if the Earth had no atmosphere, the time of the equinox would truly see the Sun’s disk split the horizon in half. However, in reality, atmospheric refraction makes the Sun appear slightly above the horizon even when it is geometrically below it.
This strong refractive effect also causes the Sun’s disk to be visible when it is less than 18 degrees below the horizon, and yet its lower edge has not completely disappeared from view.
Not as dark as it seems
Some astronomical myths die hard. One of them is that the entire Arctic region experiences six months of continuous daylight and six months of darkness. Often, “night” is only considered when the Sun is below the horizon, as if twilight doesn’t exist.
This misconception is perpetuated in numerous geography textbooks, travel articles, and guides. However, whenever the upper edge of the Sun is less than 18 degrees below the horizon, twilight to some extent illuminates the sky. (Your closed hand held at arm’s length covers about 10 degrees of the sky.) This marks the boundary of astronomical twilight when the sky is fully dark from horizon to horizon.
Twilight comes in three flavors. Civil (bright) twilight occurs when the Sun is less than 6 degrees below the horizon. It’s loosely defined as the time when most outdoor activities can continue without artificial lighting. Some daily newspapers provide a time when you should turn on your car headlights. That time is generally close to the end of civil twilight.
Illuminating details
Nautical twilight, on the other hand, is defined as the time when the Sun is between 6 and 12 degrees below the horizon. It’s called “nautical” twilight because sailors at sea can still discern the horizon well enough to take reliable readings of celestial objects using a sextant.
Astronomical twilight is even darker, lasting until the Sun gets more than 18 degrees below the horizon. During this time, the sky is considered fully dark for all practical purposes, and most celestial objects are visible without interference from twilight glow.
So, when you check your newspaper’s almanac or the weather page this Saturday (or Friday if you’re on the U.S. Pacific Coast) and look up the local times for sunrise and sunset, you’ll see that the duration of daylight, or the time between sunrise and sunset, is still a little over 12 hours and not precisely 12, as implied by the term “equinox.”
For example, in Richmond, Virginia, the Sun rises at 6:58 AM and sets at 7:05 PM. So, the duration of daylight is not just 12 hours, but 12 hours and 7 minutes. Until September 26, in Richmond, day and night are not truly equal (on that day, the Sun rises at 7:00 AM and sets 12 hours later).
On the flip side, at the North Pole, the Sun currently forms a 360-degree circle around the entire sky, appearing to skim just above the horizon. During this year’s autumnal equinox, it should theoretically disappear from view entirely, yet its disk will still be lingering just above the horizon for another 52 hours and 10 minutes.
Due to this strong refractive effect, the Sun’s disk also appears distorted as it approaches the horizon. As the Sun moves closer to the horizon, the refraction rate increases so rapidly that its lower limb rises more than its upper portion, making the Sun’s disk visibly skewed.
Not as dark as it seems
Some astronomical myths die hard. One of them is that the entire Arctic region experiences six months of continuous daylight and six months of darkness. Often, “night” is only considered when the Sun is below the horizon, as if twilight doesn’t exist.
This misconception is perpetuated in numerous geography textbooks, travel articles, and guides. However, whenever the upper edge of the Sun is less than 18 degrees below the horizon, twilight to some extent illuminates the sky. (Your closed hand held at arm’s length covers about 10 degrees of the sky.) This marks the boundary of astronomical twilight when the sky is fully dark from horizon to horizon.
Twilight comes in three flavors. Civil (bright) twilight occurs when the Sun is less than 6 degrees below the horizon. It’s loosely defined as the time when most outdoor activities can continue without artificial lighting. Some daily newspapers provide a time when you should turn on your car headlights. That time is generally close to the end of civil twilight.
Illuminating details
Nautical twilight, on the other hand, is defined as the time when the Sun is between 6 and 12 degrees below the horizon. It’s called “nautical” twilight because sailors at sea can still discern the horizon well enough to take reliable readings of celestial objects using a sextant.
Astronomical twilight is even darker, lasting until the Sun gets more than 18 degrees below the horizon. During this time, the sky is considered fully dark for all practical purposes, and most celestial objects are visible without interference from twilight glow.
So, when you check your newspaper’s almanac or the weather page this Saturday (or Friday if you’re on the U.S. Pacific Coast) and look up the local times for sunrise and sunset, you’ll see that the duration of daylight, or the time between sunrise and sunset, is still a little over 12 hours and not precisely 12, as implied by the term “September Equinox 2023.”
For example, in Richmond, Virginia, the Sun rises at 6:58 AM and sets at 7:05 PM. So, the duration of daylight is not just 12 hours, but 12 hours and 7 minutes. Until September 26, in Richmond, day and night are not truly equal (on that day, the Sun rises at 7:00 AM and sets 12 hours later).
On the flip side, at the North Pole, the Sun currently forms a 360-degree circle around the entire sky, appearing to skim just above the horizon. During this year’s autumnal equinox, it should theoretically disappear from view entirely, yet its disk will still be lingering
The Mysterious Darkness of the North Pole
The Earth, a celestial wonder, is home to a multitude of enigmatic phenomena, one of which is the captivating dance of light and darkness at the North Pole. As the autumn season unfolds, a celestial spectacle graces the northernmost reaches of our planet. Let’s embark on a journey to understand the phenomenon known as “Polar Night” and its intriguing characteristics.
Unveiling the Mysteries of Polar Night
The Commencement of Darkness
On September 25th, at the onset of autumn, the North Pole experiences a remarkable event. It’s not the immediate plunge into complete darkness, as one might assume! In reality, the civil twilight continues until October 8th. During this time, the sun dips below the horizon by 12 degrees, marking the symbolic beginning of the polar night. This is the period when identifying the maritime horizon becomes challenging.
The Essence of Polar Night
Polar night, contrary to common belief, doesn’t signify an absolute absence of light for six months. At the North Pole, one must patiently wait until October 25th for the sea ice to start melting. The sea ice, which plays a pivotal role in reflecting sunlight, prevents the North Pole from experiencing a total blackout.
A Celestial Transition
The celestial phenomenon doesn’t cease here. The polar night, characterized by complete darkness, concludes on November 13th. Until January 29th, the North Pole remains perpetually dark, marking the end of astronomical twilight and the beginning of a new cycle of twilight. During this time, the North Pole remains in partial darkness for approximately 11 weeks.
The Enigma of Polar Darkness
The concept of polar night is often shrouded in myth and misconception. Many believe that the entire Arctic region remains cloaked in perpetual darkness for six months. In reality, the term “polar night” signifies a specific astronomical event. It’s a fascinating interplay of twilight and darkness, a celestial ballet that enchants and mystifies those fortunate enough to witness it.
Conclusion
In the realm of celestial phenomena, the North Pole’s polar night stands as a testament to nature’s complex and awe-inspiring beauty. It’s a reminder that even in the darkest of times, there is a subtle play of light and shadow. As the North Pole transitions through its various phases of darkness and twilight, it leaves us with a sense of wonder and appreciation for the mysteries of our planet.
Frequently Asked Questions
Is the North Pole completely dark for six months?
No, the North Pole experiences a unique celestial event known as polar night, which lasts for a specific duration and is characterized by varying degrees of darkness.
When does polar night begin and end at the North Pole?
Polar night begins symbolically on October 8th and ends on November 13th. However, complete darkness lasts until January 29th.
What causes the North Pole to have periods of twilight during polar night?
The presence of sea ice at the North Pole reflects sunlight even during the polar night, resulting in periods of twilight.
Do people live at the North Pole?
No, the North Pole is an inhospitable environment, and there are no permanent human settlements. It is primarily inhabited by wildlife adapted to extreme cold.
Are there any unique wildlife species at the North Pole?
Yes, the Arctic region is home to various unique wildlife species, including polar bears, Arctic foxes, and various species of seals and whales.
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