The June solstice occurs at 20:46 UTC (2:46 PM, Baton Rouge). The North Pole of the Earth will be tilted toward the Sun, which will have reached its northernmost position in the sky and will be directly over the Tropic of Cancer at 23.44 degrees north latitude. This is the first day of summer (summer solstice) in the Northern Hemisphere and the first day of winter (winter solstice) in the Southern Hemisphere.
Earth orbits at an angle, so half the year, the Northern Hemisphere is tilted toward the Sun — this is summer in the Northern Hemisphere and winter in the Southern Hemisphere. The other half of the year, the Northern Hemisphere is tilted away from the Sun, creating winter in the north and summer in the south.
Solstices happen twice per year at the points in Earth’s orbit where this tilt is most pronounced. These days are the longest (in the summer hemisphere) and shortest (in the winter hemisphere) of the year and mark the change of seasons to summer and winter, respectively.