Hey, stargazers! Today, Sept. 23, we ushered in the fall season for the Northern Hemisphere at precisely 2:50 a.m. EDT. At this very moment, a perfect balance between light and dark existed on our planet. ๐
(Image credit: NOAA; NOAA Environmental Visualization Laboratory)
The Beginning of Fall 2023:
If you’ve ever wondered, “When is the first day of fall?” it was today! At this exact astronomical moment, while the Northern Hemisphere is welcoming fall, the Southern Hemisphere is greeting spring. The sun is journeying southward after spending half the year gracing the northern half of Earth. An interesting sight would be a ship sailing in the Laccadive Sea on the equator, 170 miles northeast of Addu City in the Maldives. Why? Because from that location, the sun would appear directly overhead.
What’s in a Name? Understanding the Equinox:
The term equinox originates from Latin, translating to “equal night.” This insinuates that day and night are approximately the same length everywhere on Earth during this time. But is it? Dive into the intricacies of this phenomenon here.
Debunking Equinox Myths:
Contrary to popular belief, the equinox doesn’t signify a perfect split of 12 hours day and 12 hours night. Many factors, like the atmospheric refraction and the way sunrise and sunset are defined, make the daylight during equinox a tad longer than nighttime. For instance, in Richmond, Virginia, daylight is 12 hours and 7 minutes, not exactly 12 hours, as “equinox” would suggest.
Moreover, it’s not just about the sun above or below the horizon. Twilight plays a significant role, too. Different twilight phases can illuminate the sky even when the sun is not visible. For instance, astronomical twilight โ the darkest phase โ occurs when the sun’s upper edge is 18 degrees below the horizon.
Are you curious about safely observing the sun and its myriad behaviors? Check out this informative video here.
Arctic Myths Debunked:
One longstanding myth is that the Arctic region sees six straight months of daylight followed by six months of pitch-black darkness. But this isn’t quite the case. Even at the North Pole, the total absence of sunlight doesn’t mean complete darkness ensues. In reality, twilight plays a significant role in brightening the sky. From the beginning of the sun’s disappearance on Sept. 25, civil twilight โ the brighter phase โ persists until Oct. 8. The complete, uninterrupted darkness at the North Pole is closer to 11 weeks, not six months!
Check out the night sky guide for other fascinating celestial events this September.