Edison’s light, reported in the Washington Post four days later.
The text says “A” is a glass globe from which air has been abstracted, resting on a stand, “B”.

What are the odds that three important electricity developments should all occur on December 20th? Probably, statistically, rather good. So I’ll not make much of the coincidence. Impending winter darkness was not a likely motivator – in the case of Edison’s light bulb, the electric light had been around for years before he claimed to invent it and as the New York Herald pointed out, Edisnon’s people had been working on their version for fifteen months.

On December 20, 1879, in a news-press event, Thomas Edison showed off a glowing light bulb at Menlo Park, New Jersey. He actually had a working model three months earlier (October 1879). Edison’s poorly-paid immigrant scientists had tested thousands of materials before they discovered that carbonized cotton filaments in a vacuum inside a glass bulb would throw a strong light without breaking. There was quite a fuss about the magic ball of glass, but Edison’s team had already been bested by Canadian medical student Henry Woodward who had received the first patent for the incandescent light bulb five years earlier. Edison’s company bought the Canadian patent and Edison took credit for being really, really smart.

On December 20, 1880, just one year after Edison invited the press to witness the little glowing glass globe, Broadway was lit by arc lighting which is much brighter than the punny incandescent bulbs that Edison’s company was selling. This eventually led to George Benson’s expression, “The lights are always bright on Broadway”. Except when there’s a massive power outage.

Also on December 20 (but in 1951), the first radioactive electricity hit the wires from the Experimental Breeder Reactor I, at the Argonne National Laboratory in Idaho. On that day, a string of four light bulbs lit up, using the world’s first nuclear-generated electricity. The lab’s director, Walter Zinn, had worked on the Manhattan Project and was a leader on developing the atomic bomb. Zinn, from Kitchener, Ontario, ran a staff of scientists who used a football-sized nuclear core to make enough electricity to eventually supply all the power for its own building – you might say that a secretive place in Idaho went ‘off-grid’ for the first time on December 20, 1951.

The first electric Christmas lights were a cheesy promo-gimmick by Thomas Edison who lit his Menlo Park lab with strands of lights visible to rail passengers riding past his shop. That was Christmas, 1880. Two years later, Edward Johnson, Edison’s partner in the Edison’s Illumination Company, patriotically wrapped 80 red, white and blue hand-wired light bulbs around a Christmas tree. That’s his tree, in 1880, to your right. Looks like he waited too long to buy his balsam fir, doesn’t it?  It took another 40 years before electric lights were safe and reliable enough for the public.  Until then, people hung unsafe and unreliable burning candles to their highly flammable dead pines, often just before their wooden frame homes caught fire.

Martin Luther’s Combustible Christmas Tree, around 1530.