Now that Venus has become the "Morning Star" as it passes us by in its orbit around the Sun, we get to see conjunctions or groupings like this one imaged in morning twilight on December 4. The thin waning crescent Moon seems to be beckoning to Venus at the Moon's upper right. Meanwhile, the Sun lights the horizon as a new day approaches. But it also lights the lower left side of the Moon giving it its crescent glow. It's doing the same thing to Venus which amazingly looks very much the same as the Moon! Expect even more dramatic scenes than this one in the January predawn sky. See EVENTS AND NAKED EYE VIEWING for details.
Not one of the best imaging nights, but this illusive galaxy (NGC 247) is difficult to photograph because it is low in sky in the southern constellation Cetus The Whale. It "pops up" for a short period of time in December to about 30 degrees above the horizon in southern states like New Mexico. NGC 247 is part of the Sculptor Group of 13 galaxies so named because of their proximity to the constellation Sculptor. NGC 247 lies about 11 million light years from Earth and, at 70,000 light years in diameter, it is almost 2/3 the size of our Milky Way. NGC 247 is also called, "The Needle's Eye Galaxy" because of a prominent void on its right side. Although this galaxy looks cigar shaped, it's a spiral galaxy that's tilted nearly edge on to our point of view.So far, there is no accepted explanation for the large void. However, on galactic scales, a feature like this is most probably caused by an encounter with another galaxy long ago.
Nearly all the white dots in this image are foreground stars in our Milky Way. Think of them as, "galactic snowflakes" obscuring the view of this far away galaxy. Not all the dots are stars! Look at a string of what looks like 4 blurry stars in a horizontal row near the upper right side of this image. There's also a fifth blurry smudge above right center of NGC 247. This is a string of galaxies 300 million light years distant called, "Burbidge's Chain".
This was my first attempt to image Comet 46P/Wirtanen on December 6. The colors are spread out because I took time exposures in each color. My telescope was tracking the background stars. So the comet, which was moving relatively swiftly eastward, became elongated in the direction of motion.
This is Wirtanen one night later (December 7). I shortened the time exposures because the comet was noticeably brighter than the night before so it no longer looks elongated. However, the colors are still separated.
This image was taken 14 December, two nights before Wirtanen's predicted maximum brightness. Shorter exposure times allowed me to blend the colors well to present the actual green color of the comet's coma. A coma is a cloud of gas dust and snowy water ice that forms around a comet's nucleus as it approaches the Sun. Although Comet Wirtanen is only 3/4 mile in diameter, its coma can be 1,000 miles plus wide. The green glow comes mostly from diatomic carbon (C2) although some claim that cyanogen gas (CN) also contributes to the color. There are debates among astronomers about this because CN is supposed to glow in the violet band of the spectrum. Note how the background stars shine through the thin foggy coma and the lack of a tail. It could be because the tail is on the side of the comet that we can't see or it just doesn't have one. By the time you read this, Comet Wirtanen has already passed Earth and is beginning its elliptical orbit back out toward the orbit of Jupiter. It will return in about 5.4 years. This was the closest approach (7 million miles) this comet has come to Earth since it was discovered in 1948. It will be 20 years before it gets close enough again to (maybe) see with the naked eye. I did see it just using my eyes, but I knew exactly where it was and I had to avert my vision somewhat to see it. This was certainly no, "Comet of the Century" like Hale Bopp, but the brightest I've seen since Panstarrs in 2013.