ORLANDO, Fla. – The summer solstice is an astronomical phenomenon that happens annually and begins the summer season in the Northern Hemisphere.
It’s when the sun reaches its highest point in the sky, resulting in the longest period of sunlight hours in the Northern Hemisphere and the least amount of sunlight in the Southern Hemisphere.
It begins on June 21 at 10:58 am ET, and Orlando is expected to see 14.9 hours of sunlight on this day.
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The astronomical science behind this phenomenon is due to the Earth’s rotational axis, which is an imaginary line through Earth’s center and the geographic North and South poles.
It isn’t at a right angle to the planet’s orbital path around the sun. Instead it’s tilted at an angle of 23.5° from vertical and because of that tilt, Earth has seasons.
As the Earth orbits the sun each year, its axis always points in the same direction in space. This results in the Northern Hemisphere being angled toward the sun during half of the year, then away from the sun for the other half.
When the North Pole is closest to the sun, it’s called the summer solstice in the Northern Hemisphere. In contrast, when the North Pole points farthest from the sun, it’s called the winter solstice, which is the first day of winter, astronomically.
The summer solstice does not occur on the same day each year. In fact, it’s not based on a calendar date and time. It depends on when the sun reaches the northernmost point on Earth, which is the North Pole from the celestial equator. For that reason, the date shifts between June 20, 21 and 22.
The word “solstice” comes from the Latin word, solstitium — sol (sun) and stitium (still or stopped).
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