Winter has arrived on Wednesday evening. The authorized time corresponds to 12:30 a.m. EST (9:30 p.m. PST, or 5:30 a.m. Universal Time) Thursday (Dec. 22). At this point, northern half of the planet is exactly opposite to the sun. This means that the days in the Northern Hemisphere, which were previously growing shorter, now will start growing longer.
The winter solstice depends on the motion of the heavenly bodies, so it may occur anywhere between 21st to 23rd of December, depending on where the planet is present. This happens due to rotation of Earth on its axis tilting at 23.5 degrees, so the planet leans one side or the other while traveling around the sun, leading to the creation of seasons for the people located away from Earth’s equator.
After winter solstice in Northern Hemisphere, winter starts with the end of fall while experiencing the shortest day of the year. However, opposite thing occurs in the Southern Hemisphere, where December Solstice means the start of summer.