The sun will cross the celestial equator at 3:44 PM, Central Daylight Time (4:44 PM EDT) on Sunday, Sept 22. At that time, the sun’s apex in the sky, at the exact middle of the day, will occur at the equator. The Earth’s tilt thereafter means the southern hemisphere will point toward the sun, marking the official beginning of fall in the northern hemisphere.
Another way of thinking about this that “the angle between the Earth’s axis and the Earth-Sun line changes throughout the year. Twice a year, at the spring and fall equinox (around March 21 and September 22—the exact date may vary a bit) the two directions are perpendicular” (from NASA).
The folks at livescience.com have provided an informative infographic about the equinoxes, solstices, and seasons of the year. It is embedded below. For more information, click on the graphic.
Source:OurAmazingPlanet
