By Andrea Schweitzer, PhD ~~~ This year, summer will officially begin on June 20th at 4:34 p.m. Mountain Daylight Time, which is the summer solstice. This is the day with the most hours of sunlight during the whole year, in the Northern Hemisphere. The opposite will happen in the Southern Hemisphere, which will have the longest night of the year and their winter solstice. The mid-points in between the solstices are the equinoxes, which occur in spring and fall when the hours of day and night are equal, and when the Sun is overhead at the equator. All this happens because the Earth is tilted on its axis (by 23.5 degrees with respect to our orbit around the Sun). So when we’re on one side of our orbit, the Northern Hemisphere is tipped so that the Sun is higher in the sky. The Sun’s rays arrive at a more favorable angle for warming — thus heating the Northern Hemisphere for summer. In ancient cultures, the solstices and equinoxes were considered auspicious times of the year. The …