See ‘Christmas Star’ As Planets Line Up On Winter Solstice: MD

MARYLAND — Monday's winter solstice brings a bit of an optical illusion as Jupiter and Saturn will dance in a planetary conjunction, lining up perfectly to create the illusion of a “Christmas star.” If that's not enough to brighten the longest night of the year, a meteor shower peaks that night, too, but continues through the week.

The two bright planets have been visible in the evening sky for the past several nights as they move closer together, culminating on the night of Dec. 21, the winter solstice.

If the solstice and the “great conjunction” of Jupiter and Saturn aren’t enough to get you outside, the Ursid meteor shower will offer a show of shooting stars at the same time.

The National Weather Service forecasts mostly cloudy skies over the Baltimore/DC region Monday evening and Tuesday morning. There is a 40 percent chance of rain, which could mix with snow after 1 a.m.

The last time Jupiter and Saturn were this close together was in 1623, according to NASA. As the two giant planets traveled together across the sky, Jupiter caught up to and passed Saturn in the astronomical event known as the “great conjunction."

Planets regularly appear to pass each other in the solar system, often without fanfare. Jupiter and Saturn align every 20 years or so, but it has been nearly 400 years since they moved this close together. It’s been nearly 800 years since the alignment occurred at night, as it will this year. And the two planets won’t be this cozy again until March 15, 2080.

Here, from NASA, is an explanation of what to expect:

“The closest alignment will appear just a tenth of a degree apart and last for a few days. On the 21st, they will appear so close that a pinkie finger at arm’s length will easily cover both planets in the sky. The planets will be easy to see with the unaided eye by looking toward the southwest just after sunset.”

Though the two gas giants will appear to sit upon each other, they will be hundreds of millions of miles apart in space. And though they’ll appear to form a "Christmas star" on the night of the winter solstice, that’s a coincidence based on the planets' orbits and the Earth's tilt.

“Conjunctions like this could happen on any day of the year, depending on where the planets are in their orbits,” Henry Throop, an astronomer in the Planetary Science Division at NASA Headquarters in Washington, said. “The date of the conjunction is determined by the positions of Jupiter, Saturn and the Earth in their paths around the Sun, while the date of the solstice is determined by the tilt of Earth’s axis. The solstice is the longest night of the year, so this rare coincidence will give people a great chance to go outside and see the solar system.”

Although the timing of the conjunction has led some to compare the alignment to the Christmas star, it won’t look anything like the starburst shown on images depicting Christ’s birth in a manger in Bethlehem; however, it will look like a very, very bright star.

Because Jupiter and Saturn are so bright, they can be seen in cities, and there’s no need to head to a dark sky to view them.

About an hour after sunset, which occurs at 4:46 p.m. in Maryland, start scanning the southwest sky. Jupiter will look like a bright star and will be easy to spot, while Saturn will be slightly fainter and will appear just above and to the left of Jupiter. Jupiter will overtake Saturn, then the planets will reverse positions in the sky.

The window to see the conjunction is short. Both planets quickly set after sunset. You’ve only got about two hours before they disappear.

The solstice arrives in Maryland at 7:22 a.m. Eastern Time. On the first full day of the calendar winter, we’ll see nine hours and 23 minutes of sunlight.

The winter solstice occurs at the exact moment the North Pole tilts the farthest away from the sun. On Tuesday, the days begin growing a wee bit longer every day until the summer solstice, after which the days start getting shorter again.

The winter solstice may explain why Christians celebrate the birth of Jesus in December. The Bible isn’t specific about when Jesus was born, and some people believe Dec. 25 may have been selected by Pope Julius I as the date of Christ’s birth to replace the ancient pagan Roman midwinter festival called “Saturnalia” with a Christian holiday.

Stick Around For Shooting Stars

If you can and the weather is decent, stick around outside. On this most spectacular of nights, the Ursid meteor shower, which runs from Dec. 17 to 26 every year, reaches its peak.

Actually, the shower peak occurs in the early morning hours of Tuesday, Dec. 22. Ideally, you should start looking for shooting stars around 1 a.m. The first quarter moon sets in the early evening, leaving dark skies that will make meteors pop.

The Ursid meteor shower, named after the constellation Ursa Minor, the Little Bear, is a low-key event producing only about 10 shooting stars an hour. They take a back seat to the more robust Geminid meteor shower, but occasionally produce outbursts when up to 100 shooting stars an hour may be visible.

The shooting stars will appear to come from just to the left of the bowl of the Big Dipper, which will hang low in the northern sky during the peak.

Meteor showers occur when Earth plows into a stream of debris left behind by a passing comet. When these particles — normally about the size of a grain of sand — enter Earth’s atmosphere, they burn up in spectacular displays of shooting stars.

Particles left behind centuries ago by the dim comet 8P/Tuttle — due to swing past the sun again in August 2021 — create the Ursid meteor shower.