While most schools are already out for summer vacation, summer in the Northern Hemisphere does not officially begin until Saturday, June 21 at 4:51 a.m., Mountain Daylight Time (MST.) At that time, Earth is at the point in its orbit where the Northern Hemisphere is leaning most toward the direction of the Sun. Due to this geometrical relationship, the Sun rises at its most northeasterly point along the horizon, reaches its highest possible altitude for the entire year in the sky at mid-day, and sets at its most northwesterly point. This results in about 15 hours of daylight in Utah.
We call this the summer solstice. The word “solstice” means, “Sun standing still.” For a few days before and after the solstice, the Sun’s height in the sky at mid-day and its location along the horizon at sunrise and sunset does not perceptively change. By the end of the month, observers will begin to notice that the Sun sets a little farther south each evening, and rises a little farther south each morning. It will also appear slightly lower in the sky at mid-day. This will continue until the Sun rises and sets at its most southeasterly and southwesterly points on the winter solstice on December 21. On that day, the mid-day Sun will be at its lowest height of the year and Utah will experience about 9 hours of daylight.
When the Northern Hemisphere leans most in the direction of the Sun, the Southern Hemisphere leans most away from the Sun. For inhabitants of the Southern Hemisphere, June 21 is the beginning of winter.