Winter Solstice 2020: What to know about the shortest day of the year

The 2020 winter solstice is at 5:02 am ET / 2:02 am PT, Monday, December 21, marking the official start of astronomical winter and the shortest day of the year for the northern hemisphere. In the southern hemisphere, that day is the summer solstice and the longest day of the year.

The inclination of 23.5 degrees in the axis of rotation of the Earth creates an aspect of rising and falling sun during a year. During the winter solstice, the northern hemisphere is inclined to the farthest distance from the sun, bringing weaker and colder temperatures.

The inclination of the Earth – not our distance from the sun – is what causes winter and summer. In fact, the Earth is closer to the sun in winter than in the summer months.

The solstice is not the only major astronomy event since Monday.

During the “great conjunction” of Monday, Jupiter and Saturn will form a “double planet” that appears at only a tenth of a degree – or about an inch thick at arm’s length.

This phenomenon has been dubbed the “Christmas Star” in connection with the heavenly light that guided the three sages to Jesus in the story of the birth of the Christian Bible.

Skywatchers can differentiate Saturn and Jupiter from stars, as the planets will appear “brighter and more solid in the sky.”