When the Earth was formed, it didn’t look a whole lot like it does today.

When the Earth first cooled enough to have a solid surface, some hundreds of millions of years after it formed, the atmosphere was, to us, a toxic mess. Carbon dioxide, water vapor, carbon monoxide, ammonia, methane… but no free oxygen. O₂ is very reactive chemically, so it was all locked up in other molecules.

Eventually Earth got wet. The water either came up from underground (volcanoes and such) or it fell from the skies as comets, but either way we got oceans. Complex chemicals arose in those oceans, and then, one fine day, a complicated chemical indeed was able to make duplicates of itself. It went forth, and multiplied. Eventually this became life — able to ingest, excrete, and multiply.

A billion years later, land formed and became a permanent feature of the young Earth. Volcanoes had been primarily undersea, but now they became land-based as well. When this happened (or so it’s thought) they started belching out oxygen into the atmosphere the volcanic emission stopped stripping oxygen from the atmosphere. At some point, some (probably) unicellular form of life was able to metabolize the chemicals in the atmosphere, and excrete oxygen. Note added later: Up to this point, volcanoes had been primarily undersea, but now they became land-based as well. When this happened (or so it’s thought) they stopped stripping that oxygen out of the air, allowing it to accumulate.

Either way (or, more likely, both), the air changed over time, became oxygenated.

The atmospheric levels of oxygen rose… and eventually some form or forms of life evolved to use that waste product. Since oxygen is chemically reactive and releases lots of energy when combined with other chemicals, it’s an excellent fuel. The life that was able to utilize it had more energy, and wound up dominating the planet.

That, over time, eventually became us.

The release of O₂ is called the Great Oxidation Event (though I think that should be Oxygenation), and it is thought to have happened 2.3 to 2.4 billion years ago (over 2 billion years after the Earth formed). But scientists have now found that it may have happened a little earlier than that by 50-100 million years.

They took a kilometer-long core sample (and may I say here, YIKES! That’s a big core) from Australia, and by analyzing its composition they were able to determine the atmospheric content from all those eons ago. From that, they found when the Earth’s atmosphere started getting its oxygen. In other words, the actual increase of O₂ has been seen for the first time.

“We seem to have captured a piece of time during which the amount of oxygen was actually changing — caught in the act, as it were,” said Ariel Anbar, an associate professor at Arizona State University, Tempe, and leader of one of the research teams.

That gives me chills. Imagine! 2.4 billion years ago, the Earth was mostly covered in ocean. The ocean wasn’t blue, it was probably greenish due to the high levels of iron and lack of oxygen. Breathing the air would have killed you in minutes. And somewhere, deep in all that murk, a little tiny cell split in half, and the copy wasn’t perfect. Did a cosmic ray zap it? Was there some environmental pressure that altered the gene map? However it happened, the daughter cell’s chemistry zigged instead of zagged, and it was able to use oxygen, which was probably a poison to life up until then. Trillions of generations and far, far more DNA alterations later, and we can dig into the Earth itself and see how all that lovely oxygen got things started.

This story isn’t over yet, but we’re starting to be able to read the beginning.

Hey, cool: Rebecca won one of the three slots on the Public Radio Talent Quest!

Obviously, this was due to the BABloggees voting for her. She owes me now.

Previous posts on this: here and here and here.

It’s a been a long, difficult road, but the Dawn mission launched this morning and is on its way to the asteroid belt. It will go to Vesta and Ceres, the two largest asteroids, orbit them, and take lots and lots of data. The images will be simply spectacular, and it will also take spectra and mineralogical studies to determine the composition and history of these two ginormous rocks in space (Ceres is about 1000 km across, Vesta 500).

Search for the word Dawn in my blog search engine to get an idea of how tough this mission has had it: it was basically canceled, then reinstated, then delayed, and and and. My friend Amara has an excellent blog post with some more background.

In a few weeks I will be wingin’ it to Alberta Canada to participate in the Alberta Festival of Science from October 17 – 20! This annual fete is held in central Alberta, in the town of Wood Buffalo, which basically exists because there’s lots of oil in the area. Several companies have plants there, so a town popped up. It’s a bit remote, but actually quite a few folks live there: the population is over 50,000.

Anyway, this have this pretty big affair there every year, and they invited me to come talk about the Moon Hoax. I’ll be giving the talk twice, on Friday at 8:30 a.m. and again at 10:00 a.m.

If any BABloggees are in the area, come see! And if I’m not enough of a draw, then maybe this might change your mind: on Saturday night I’ll be MCing a panel with Kari, Tory, and Grant from the MythBusters Build Team!

Yes, I do in fact rawk.

If you’re not a Doctor Who fan, then you can skip this post. If you are, and you don’t want any spoilers at all for Season 4, then skip this post immediately.

(more…)

Sometimes astronomy news isn’t spectacular, but it is still so way cool.

SOHO is an observatory that is parked about a million miles towards the Sun, where it can stare at the nearest star all the time. One instrument, LASCO (the Large Angle and Spectrometric Coronagraph), has a little paddle that blocks the fierce light of the Sun itself so that it can see the fainter hiccups and belches of billions of tons of plasma erupting from the surface.

But it can also see stars in the background, and planets, and, sometimes, comets. They are really amazing to watch in the animations as they streak in toward the Sun. Most — and over a thousand have been seen — evaporate away and are never seen again.

But a sharp-eyed observer named Sebastian Hoenig, a German PhD student, found one that came back! Although it’s not clear from the press release, I assume he was tracking comets and calculating the orbits of them. In 2005 he realized that two comets may be one and the same because the mathematics of their orbits (shape, size, period, etc.) were so similar. Assuming he had seen two apparitions of the same object, he predicted it would return in early September, 2007. Bang! There it was, right on schedule.

Now called, P/2007 R5 (SOHO), it’s a weird one. Comets usually get a tail, especially when close to the Sun. This one doesn’t. But it does brighten a lot when it gets close to the Sun, like comets do. It’s probably an extinct (well, almost extinct) comet nucleus. It used to be rock and ice, but now it’s almost all rock, with some ice still buried inside that only sublimates (turns into a gas) right when the comet is closest to the Sun.

It’s tiny, maybe 200 meters across, so it’s basically invisible to Earth-based telescopes, and only becomes visible when it’s near the Sun. Over time, any comet could become one of these weirdos, so it may not be all that weird– there could be thousands more like it on short orbits (this one has a four year orbit).

If you’ve never done it before, go poke around the SOHO website (linked above). It’s an amazing success story from NASA and ESA, with tons of incredible information, pictures, and animations. It’s time well spent.

I don’t generally do this, but for her I’ll make an exception.

I stumbled on a singer whose voice I just love. Her name is Marian Call, and I found her through her MySpace page, of all places; I followed a comment she left on Nathan Fillion’s page. Nathan played Mal Reynolds on "Firefly", and you know how much I love that show, and evidently so does Marian. Anyway, I went to her page, and the music loaded automatically. Normally I find that incredibly irritating, but once in a great while it pays off. It did in this case.

Marian’s music is hard to pin down; it’s like folk but not at all cloying like so many folk singers are. It’s not dance or rock; it’s simple, personal, small band coffee-shop kinda stuff. Sorta. If you know Sara Hickman, you know Marian. Her voice is clear and beautiful, and not at all artificial like every gorram singer on the radio these days (and Marian uses that word in one of her songs; like I said, Firefly, baby). The words are intelligent — imagine that! — and she has a fantastic musical sense.

A Firefly connection: turns out there was a contest to write a song about Saffron, the lovely but warped beauty who took Mal for all he’s worth not once, but twice on the show. Marian’s song for that was perfect, and I mean perfect. She even sounds like Saffron.

Anyway, you can listen to her songs on her MySpace page, and if you like them, her CD is available on the Marian Call website. I make no money from this, nothing at all like that. I just think she’s great, and could use some free publicity.

My one complaint is that she’s in Alaska and that it may be a while before she makes it down to Boulder to sing here. But if she does, I’m there.