The purpose of this feature is to give scout leaders, educators and naturalists an idea of some of the natural events coming up each month.  We will try to cover a variety of natural events ranging from sky events to calling periods of amphibians, bird and mammal watching tips,  prominent wildflowers and anything else that comes to mind.  We will also note prominent constellations appearing over the eastern horizon at mid-evening each month for our area for those who would like to learn the constellations.  If you have suggestions for other types of natural information you would like to see added to this calendar, let us know!

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Notes From December 2023

On December 7th, after a cold front had swept through, I had an unusually clear winter sky. It was one of those nights where it seemed like an extra layer of stars had been added and it was just stunning! It was predicted to be quite cold, but I couldn't resist trying for The Dolphin Head Nebula, an unusual bubble nebula in Canis Major. It wasn't a particularly easy target since it never climbs more than 30 degrees above the southern horizon. That meant that I would be imaging through twice the air mass that I typically do.

Sirius put on a colorful light show as it rose through the turbulent layers of the atmosphere close to the horizon, showing all of the colors of the rainbow. The cold temperatures and wind created a silence in the winter woods surrounding the observatory. Only the sound of a distant freight train making its way down Chattanooga Valley far below broke the silence. Early in the evening the telescope tube had already started to frost over. The dew heaters managed to keep the optics clear of frost. A persistent wind made it feel colder. The camera loves cold temperatures and I was able to cool the camera sensor to -30 degrees Centigrade, which greatly reduces noise in the images.

To find the location of the nebula, begin at Sirius and work your way down the stars of Canis Major toward the southern horizon. Sirius is the brightest star in the night sky. Though it's larger and brighter than our Sun, its brilliance is mainly due to its close proximity. It's only about 8.7 light-years distant, and the fifth closest star system to our Sun. All of the other stars of Canis Major shown in the charts above are much farther away.

The close up of Canis Major shows a typical field of view for many common binoculars and is six degrees in diameter. If you aim your binoculars at the position shown in the diagram, you will see two faint orange stars. They are Omicron 1 (o1) and Sigma Canis Majoris. The upper star, Omicron, is the brightest star in the image of the Dolphin Head Nebula below. On a clear night you should be able to see o1 with your naked eye. The orange color will be distinct in binoculars.

The star marked EZ Canis Majoris is the central star of the nebula. It's a little too faint to see with the naked eye, but it's not hard to see in binoculars. Both stars are visible in the image below, though the image has been rotated 90 degrees from the finder chart. The nebula itself is quite faint. I found a record of the brighter parts of it being observed with a 10" aperture telescope with an Oxygen III filter.

 Can a nebula be playful? If so, the Dolphin Head Nebula probably qualifies, although I think a better name would just be the Dolphin Nebula. To me the nebula looks like a complete celestial dolphin swimming towards the viewer.

 The nebula is cataloged as Sh2-308. The bluish star you see at the center of the nebula, EZ Canis Majoris, is a Wolf-Rayet star. Wolf-Rayet stars are among the most luminous, most massive, and most briefly detectable stars known. The nebula surrounding this star looks like a planetary nebula, but planetary nebulae are created by aging red giant stars. The central star of the Dolphin Head Nebula will at some point become a supernova. Moreover, since its mass is over twenty times the mass of our Sun, it will probably wind up as a black hole. It is one of the 10 brightest Wolf-Rayet stars known.

The bluish wisps of nebulosity in the image are primarily ionized oxygen that has been cast off of the central star. The diffuse red areas are ionized hydrogen. The nebula is quite faint, but if you could increase its brightness to where it was visible to the naked eye it would appear larger than a full Moon in the sky. The diameter of the nebula at its widest point is about 60 light-years. Current distance estimates for the central star and nebula are around 4,900 light-years, though some estimates are as low 1,900 light-years.

*For those who haven't read Douglas Adam's A Hitchhiker's Guide to the Galaxy, the book begins as Earth is about to be destroyed to make way for a hyperspace expressway for more advanced civilizations. The dolphins have already arranged to leave the Earth. According to Adams;

"The dolphins had long known of the impending demolition of Earth and had made many attempts to alert mankind to the danger...The last ever dolphins message was misinterpreted as a surprisingly sophisticated attempt to do a double backward somersault through a hoop whilst whistling 'The Star-Spangled Banner', but in fact the message was this: 'So Long, and Thanks for All the Fish.'"

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 Sky Events for January 2024:

The Quadrantid Meteor Shower reaches its brief peak in the early morning hours of January 4th. The peak only lasts around six hours, centered around 4:00am EST. Face northeast. A reclining lounge chair, warm clothes or a sleeping bag and perhaps a warm beverage will make things a lot more comfortable.

Earth reaches perihelion, its closest approach to the Sun for the year, at 7:39pm EST on January 2nd.

Recommended:  The Frogs and Toads of North America, Lang Elliott, Houghton Mifflin Co.