December 1 2020

This last month of the year, and start of winter provides quite an interesting bit of weather and science geek stuff to talk about.  This month brings us the winter solstice, which means the longest nights of the year. It also will feature the Great Conjunction of the two largest planets in our solar system not seen in almost 400 years.

We also have other planets to view, and a prime International Space Station Flyover.  All that info is posted below. But let’s start with the weather and the sun.

Winter Solstice Sun In Baltimore

 

 

On December 21, the shortest day of the year, this is also the lowest sun angle. But this is NOT the latest sunrise and earliest sunset.   It is a strange result of the tilt of our earth, while the sun is rounding the corner on the elliptical orbit. In fact, Earth reaches the closest point to the sun on January 2 (2021). This is called perihelion and we are about  million miles closer to the sun than in July. But it doesn’t influence our temperatures.

Latest Sunrise: 7:25 AM on December 27

Earliest Sunset: 4:43 PM on December 1 -14 (about the same for 2 weeks).

 

Comparing Sun Angle

At Noon on The Winter Solstice, the highest sun angle of the say will be 27.3º above the horizon.  This is the same height above the horizon in Baltimore as only 8:15 AM on the Summer Solstice.

 

December Weather In Baltimore

Normal High

• 1st = 50ºF
• 31st = 42ºF

Normal Low

• 1st = 32ºF
• 31st = 25ºF

 

Coldest: -3ºF on December 30 in 1880

Hottest: 77ºF 6th and 7th in 1998; 29th in 1984

 

Average Snow = 3″

Most Snow = 20.4″ in 1966

*This is a source of debate. The first of three blizzards in the 2009-2010 winter was on December 19, 2009.  Originally this was reported to dump 19 inches of snow and the month over was 21″. But NWS revised the snow records downward after the fact. December 2009 is on record now with a second place total of 20.1″

 

 

Night Sky Shows

International Space Station Flyovers (Week 1)

December 6

• 6:34 PM to 6:37 PM
• Elevation 68º = Prime Show!

 

December 7

• 5:46 PM to 5:52 PM
• Elevation 53º = A pretty good show!

 

Moon and Planets

The Full moon is called the Cold Moon, and will be at the end of the month. But it will give us a few shows before that.

 

December 11 to 13:

If you can brave the cold, wake up an hour before sunrise and see the crescent moon with Venus in the East sky.

 

December 16:

The moon will be in the southwest sky in the evening, in view of the approaching Great Conjunction of Jupiter and Saturn.  

 

December 21: The Great Conjunction

Jupiter and Saturn will appear the closest in the sky since 1623 when Galileo.  That was 14 years after he made his first telescope. \

The separation will be equal to 1/5 of the width of our view of the moon.  It might appear as one very bright star, but binoculars or a simple telescope will show them apart.

 

When/Where To View:

Evening in the southwest, between sunset and 7 PM.

These two planets are already doing their dance in the sky. They will continue to get closer for the first three weeks of the month.

 

 

The Full Moon: Cold Moon on December 29th

This is officially on the 29th, but may be listed as the 30th on some calendars. If it is clear, you may not be able to see any difference.

 

 

Meteor Showers

Geminid Meteor Shower

• Rate: 50 + per hour
• December 13 to 14
• Look East
• Before Dawn

 

Ursid Meteor Shower

• Rate: 5 to 10 per hour
• December 22
• Look North-Northeast between the Little and Big Dippers