Hello, I'm Hank Green, welcome to a special year-end edition of Sci-Show News.

The holidays are a time for celebration as well as a time for reflection for many of us, so while we're all spending time with loved ones, and trying not to drink too much eggnog, I'd like to take a few minutes to remember some of the great minds in science that we lost this year.

(Intro)

I personally will remember 2012 for lots of wonderful things but it will always also be the year that we lost Neil Armstrong. He will of course be forever remembered as the person to first set foot on the moon but one aspect of Armstrong's life that bears emphasizing is his love of knowledge: acquiring it for himself, and helping others learn.

Unlike many other test pilots and early astronauts of his day, Armstrong was a student and teacher for much of his career. He started studying engineering when he was 17 and after a tour of duty in the Navy where he learned to fly, he got his Bachelor's Degree in 1955. Then after making history in the Apollo 11 mission, he didn't go into retirement or the celebrity circuit, he went back to school and completed his Master's degree in Aeronautical Engineering in 1970. He actually wrote his thesis on the many historic and unique features of the mission he'd just completed.

From there he returned to his native Ohio and help build the University of Cincinatti's burgeoning Aerospace Department where he was Professor of Engineering for eight more years.

These are just some of Armstrong's contributions to science that are too many to mention now but you can see my tribute to him here (01:32).

Also among Armstrong's ranks we lost Sally Ride. To many she is known as the first American woman in space, in flights of the space shuttle Challenger in 1983 and 1984, but she was recruited by NASA just after getting her PhD in Physics in 1978 with a focus on Astrophysics.

This background notwithstanding when her first mission on Challenger drew near she had to tolerate questions from the press like "What do you do if you get your period in space?" and "Do you cry when things go wrong on the job?". Ride put up politely with such questions and went on to show the world what she was made of, not only in her two shuttle missions, but also in a career dedicated to combating ignorance. She became a Professor Emeritus of Physics at the University of California at San Diego, advised a national panel on arm's control and eventually founded her own company, Sally Ride Science, dedicated to inspiring young girls to pursue careers in science, engineering, and technology. 

We also lost a host of Nobel Laureates this year, whose accomplishments range from showing us how our brains work, to changing the earth's environment for the better. 

Virologist Renato Dulbecco was awarded the 1975 Nobel Prize for Medicine for his discovery that viruses could cause cancer by inserting their genetic information into a host cell by changing its genetic makeup. His work also illuminated how cancer grows at a molecular level and led to the conceptual breakthrough that cancer can stem from genetic mutations a course he investigated for the rest of his career.

Another scientist who truly changed the world was F. Sherwood Roland an environmental chemist who in 1974 discovered that the earth's ozone layer was disappearing and that a chemical was to blame. Roland investigated chlorofluorocarbons or CFCs, synthetic gases used in aerosols, refrigerants, and Styrofoam. CFCs were widely used because they were so stable, but Roland suspected that they would eventually decay in the atmosphere from exposure to sunlight. So over many years and in cities around the world he collected air samples and found that while CFCs were accumulating rapidly, levels of ozone were dropping. Roland was right, sunlight was breaking CFC molecules into chlorine and other compounds that in turn caused ozone molecules to decay.

Because of Roland's research, CFCs were banned in most countries and the ozone layer is now slowly recovering. He and his colleagues were awarded the Nobel Prize in Chemistry in 1995.

We also lost two of the men who helped make organ transplants possible: Joseph Murray and E. Donnall Thomas. They shared the Nobel prize in 1990 for Medicine for their work in conquering the vexing problem of tissue rejection. Together they found that tissues could be successfully between people if the recipient's immune system was repressed just enough using radiation and later immune-suppressing drugs.

Murray performed the first successful kidney transplant between identical twins in 1954 and later showed it to be possible among people who aren't related at all. 

Donnall Thomas meanwhile used a similar drug regimen to perform the first bone marrow transplant in 1958 by injecting healthy bone marrow stem cells into a patient with leukemia.

Finally, one of the most famous scientific dynasties, the Huxleys lost a member this year. Grandson of Thomas Henry Huxley, the father of comparative anatomy and half brother of author Aldous Huxley, Andrew Huxley gained fame for his achievements in Physiology ultimately winning the Nobel Prize for elucidating how organisms use electricity to move. 

To untangle the puzzle of bio-electricity, Huxley and colleague Alan Hodgkin researched giant squid, which have a single enormous nerve cell called a giant axon that runs the length of its entire body. By running a current through that cell they could measure the electricity traveling down its length in waves, the first time that this dynamic called action potential was observed. The two share the 1963 Nobel Prize for physiology for changing the way we understand how we move, think, and feel. And there are countless other women and men whose contributions to scientists will live on after them, for those I haven't mentioned, please share them in the comments below.

Segment number two of this special episode: department of corrections. I love facts, but not if they're wrong, because if they're wrong they're not facts. They're just stuff that someone said. So let me set the record straight about a couple of things that, yeah, I messed up on.

First, my knee is aching because of this arrow I took at a recent dose on three world changing chemist experiments. One of them was Michael Faraday's 1834 escapade with a couple of pieces of metal, a pan of water, and some electricity in which he discovered ions. In describing his equipment in terms in coined to name them I said that the cathode was the positive electrode in this experiment. And this was not wrong, but a lot of you started throwing your mnemonic devices at me demanding clarification. Panic, you said or Pennsylvania, North Carolina. And good for you, you retained an important rule of thumb in electrical systems -positive anode, negative cathode. So why did I say that the cathode was positive? Because it was. Faraday's setup was a galvanic system: one that creates a current like a battery, so the flow of electrons runs to the cathode, which is positive. The PANC arrangement applies for electrolytic systems, ones that use electrical currents that are applied to them; in those kinds of cells the cathode is negative.

So cathodes are not always the positive electrodes, you're right, but that's nothing compared to what I said in my breaking news update about the MESSENGER space craft. I told you the MESSENGER has detected water ice at and near the surface of Mercury's poles but in all the excitement of getting this weird news to you we described Mercury as the hottest planet in the Solar System which it is not. Temperatures on the surface of Mercury can reach 427 degrees Celsius which is hot; hot, hot, hot, hot enough to make even me want to take off my shirt, but because its atmosphere is so thin Mercury's surface loses much of that heat at night, radiating it back out into space.

As many of you very rightly pointed out, Venus has by far the highest average temperature of any planet in the solar system and also the highest temperature. As much as 470 degrees Celsius. Even though it's farther from the sun, Venus is shrouded in this famously dense atmosphere made up mainly of carbon dioxide, which makes it extremely good at retaining solar radiation. It basically invented the greenhouse effect. An affect humanity liked so much, apparently we tried to imitate it.

Anyway, thank you our viewers for not forgetting to be awesome and for calling us out on those mistakes and to Mr. Faraday and the planet Venus, you have my humblest and most abject apologies.

Thank you for watching this episode of Sci Show, we're on Facebook and Twitter and leave your comments below if you have any other corrections you'd like to make, or just any comments or ideas or suggestions, and of course if want to keep getting smarter with us you can go to youtube.com/scicshow and subscribe.