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What's Up in SWFL Skies

December 2023

Moon Phases December 2023 (Eastern Time Zone)

    5            12             19               26

   3Q          New          1Q          Full Moon

The Geminids Are Here!
Geminids: the Fabulous December Meteor Shower

The Geminids are a fairly high-volume meteor shower caused by debris from the orbit of the 3200 Phaethon, an Apollo-class asteroid with a "rock comet" orbit. This would make the Geminids, together with the Quadrantids, the only major meteor showers not originating from a traditional, icy comet. As a result of its high orbital eccentricity, the surface temperature of 3200 Phaethon at perihelion could reach around 1,390 °F! No wonder bits of the surface flake off and make the orbit messy - and when we pass through that orbital trail the nights of 13-15 December, the messy bits of dust and rock will streak through our skies as a meteor shower: the Geminid shower.

December 21: 'Winter' solstice


On Dec. 21, Earth's North Pole will reach the greatest tilt away from the sun, known as the Winter solstice because it's winter in the northern hemisphere. This marks the start of astronomical winter for us here in Fort Myers, but meteorological winter starts December 1st. Of course, in Australia, it's midsummer!



Mercury can be seen just after sunset at the start of the month, low in the west-southwest. It gets a little higher until December 7th then fades rapidly as it plunges in its orbit back toward the Sun from our point of view. By December 16th you'll be lucky if you can see it against the sunset glare. But it is *fast* - by Dec 27th if you get up and it's clear, check out the very low ESE horizon to see Mercury reappearing with Mars just to its right, as "morning" objects! They will be very low and hard to spot, but over the next weeks, Mercury will soar higher and brighter each dawn.

Through most of December, Mars is invisible in our sky, at almost its greatest distance from us - the far side of the Sun The Sun will be too close to Mars in our sky at the start of the month for us to see the little red planet, but it re-emerges as a "morning object" rising before the Sun starting around December 27 (when it's just to the right of Mercury), and Mars will become more visible as it rises higher in the pre-dawn sky throughout January.

Saturn will be high in the southwest by the time it gets fully dark, but it is massively outshone by brilliant giant Jupiter (farther to the east). Poor Saturn! Still a lovely  object to view in your telescope :-)


Jupiter will be the very bright planet high in the south at the start of the night all month long, slowly coming down from as high in the sky as it will get all year, in the course of this month. Jupiter is visible for the first 2/3 of the night and passed "opposition" to the Sun on November 3rd. This is (still) the best time of the year to observe our largest and most massive gas giant, since "opposition" means it's closest to Earth at this point in our respective orbits: only four times the Earth-Sun distance from us (370 million miles), so if you do have a telescope, or even really powerful binoculars, take a look! Remember: Jupiter completes a full rotation on its axis in under 10 hours, so if you look early and do NOT see the Great Red Spot, look again a few hours later, and so forth. Jupiter is quite bright, but it still plays second fiddle to brilliant Venus, which will dominate our predawn sky!

Venus will be high and bright in the pre-dawn eastern sky each morning, pretty much all through December. Venus is the brightest planet, when it's at its brightest (at two points in its orbit, on each side of the Sun from our point of view - one such point took place September 19th). But it’s going to get a little less brilliant each day as the month proceeds.


Moon and Stars

December 9, from 6 am to sunrise: If you are an early riser and it's clear this pre-dawn, one of the most beautiful celestial sights awaits you!  Look to the southeast for a slender waning crescent moon just 3 degrees from the brilliant planet Venus.


December 11, around 8:17 pm: tonight, an asteroid called 319 Leona will pass in front of Betelgeuse and block its light for a few seconds - but this occultation will only be visible south of us! Everglades City may get a chance to see Betelgeuse "wink out", and Homestead and the Keys definitely have a good chance of being able to observe this, according to the majority of the models! Just thought I'd mention it in case you want to go chasing the occultation of Betelgeuse!

December 24 - 27

The moon will be waxing gibbous and almost full at Christmas this year, so for displays of holiday lights and photo opportunities, this will be a good year!


At the Planetarium


We show four different planetarium shows, two on odd-numbered days and the other two on even-numbered days, so that visitors can attend planetarium shows at 12:15 pm and at 2:15 pm two days in a row and never see the same shows twice.  Every Sunday, we have an extra planetarium show with a science discovery emphasis at 3:30 pm. We do a morning "sensory Sunday" show each month, usually on the first Sunday, for people with sensory challenges who want a kid-appropriate show with low volume and a bit more lighting in the planetarium (but please reserve your spot ahead of time for these as they can fill up). We also have at least one special planetarium evening show or presentation at 7 pm (sometimes a show with a talk, too) per month. These are fun and educational and usually related to what is going on that month in our SW Florida skies. Other times we may cover some cool topics in-depth. Our planetarium shows usually have descriptions posted in our calendar. Just click on the individual items for the relevant day in our Calendar to see a full description of the shows or events for that day. You get a "being there" full-surround video and audio experience with all of our shows, and an optional "star walk" guide to our current night sky.


Our special planetarium presentation this month is TWO occurrences of the super-popular investigation "The Star of Bethlehem," live in the dome with Planetarium Educator Todd Sherman, with questions allowed.  This exploration will take place on Wednesday, December 20th at 7 pm, and again (for those who couldn't make it Wednesday) on Friday, December 22 at 7 pm: tickets are available by clicking on the link in the premiere page, here. We also will have Holiday Lights trail open Wednesday through Saturday of that week, so you can catch both!


The planetarium presentations are mask-optional -- because you are indoors with other people for about 45 minutes, you might want one, but it's up to you. Planetarium shows are 6 days/week at 12:15 pm and at 2:15 pm (plus an "extra show" at 3:30 pm on Sundays). Please check our Calendar for details. To ensure getting a seat (or the seat you want), please arrive fifteen minutes before the scheduled show time (in "season" especially). We do have two hand sanitizer stations in the lobby, and we thank you for helping us keep everyone safe by distancing, wearing your masks if you have reason to throughout the show and using the sanitizer upon entry. Thank you!

Our friends at the SW Florida Astronomical Society's regular first-Thursday "Meetings with Speaker Series" are hybrid live and Zoom meetings for now (Zoom portion needs to be arranged in advance, see their website for contact info and updates: Some of the members are discovering that being able to attend SWFAS from anywhere in the world is actually pretty convenient! Some of the speakers are pretty famous -- how does SWFAS manage that? Well the speakers, too, can Zoom if needed!

To get a printable (black on white, saves ink) map of the night sky (note: N-S-E-W directions will only make sense if you hold the map overhead to look at it), visit the free download site of the AWESOME

To spot the International Space Station moving through your sky, try NASA's Spot The Station website! Or to add in the Hubble and various other bright satellites, you can try Sky & Telescope's Tracker page. Or Satflare, of course.

Visit the Planetarium for updates on all of our space-related wonders!  You can even rent the planetarium, for your own space-themed party, wedding, celebration of life, meeting, meditation session, or other cosmic event. If you have guests who are immunocompromised, please don't forget the masks, though, whether regular or space-themed.


Hope to see you soon at the Center, 

– Heather Preston, Planetarium Director

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