Five things that make this year’s winter solstice an unusual ‘shortest day of the year’
By Scott Dance
Dec 19, 2018 at 5:00 AM
Winter arrives Friday with the solstice at 5:22 p.m. EST — the moment at which Earth’s axis tilts the Northern Hemisphere farthest from the sun’s warmth.
Here are five things that make it a special one:
It’s not going to feel like winter
Temperatures could hit 60 degrees on Friday around the Baltimore region, almost 20 degrees warmer than normal for this time of year. More rain is also in the forecast, potentially bringing the region’s record precipitation total beyond 70 inches.
It won’t be Baltimore’s warmest first day of winter, though — that came Dec. 21, 2013, when temperatures reached 71 degrees at Baltimore-Washington International Thurgood Marshall Airport.
It (nearly) coincides with the Long Night’s Moon
December’s full moon, known as the Long Night’s Moon or the Cold Moon, falls just about on the “longest” night of the year. It arrives at 12:48 p.m. Saturday, so technically on the second day of winter.
The days are still getting “shorter” as we approach the winter solstice Dec. 21, but after Friday, sunsets begin arriving later in Baltimore for the first time since late June. The sun will set at 4:43 p.m. Friday night.
Look in the southeast before sunrise and see Mercury and Jupiter appearing as if they’re about to collide in space (don’t worry, they’re hundreds of millions of miles apart).
Mercury is the most difficult of the visible planets to spot, because as the innermost planet in the solar system, it never appears far from the sun. That doesn’t give much time to find it before sunrise.
On Friday, Jupiter will appear right next to it, making it a little easier to find. Jupiter will be the brighter and larger of the two. Look about an hour before sunrise, in the 6 o’clock hour.
There’s also a meteor shower
By Friday, the Ursid meteor shower will be nearing its peak. The shower gets its name because its meteors appear to emanate from Ursa Minor, also known as the Little Dipper.
It’s not the best meteor shower of the year — as many as 10 meteors can be visible per hour, and the aforementioned full moon could outshine some of them — but it’s one more celestial event of interest.
The day will be longer than 24 hours
OK, this is actually the case for every winter solstice, but it’s nonetheless odd. At this time of year, each day is actually about 24 hours, 30 seconds long. (Each solar day, that is — the time it takes for the sun to reach its highest point in the sky from one day to the next. The 24-hour clock doesn’t change.)
As EarthSky.org explains: It’s because Earth is nearing its closest point to the sun in its elliptical orbit. That makes the planet move slightly faster than average through space, which means that it must rotate a little farther than average to reach its next solar noon.
When we talk about the length of the day at the solstice, though, we’re usually referring to the amount of time the sun spends above the horizon. That hits a nadir at 9 hours, 24 minutes Friday — after which the days start getting “longer” again.