How big is the Churyumov-Gerasimenko comet?

With a nucleus size of 3.5×4 km, 67P/Churyumov–Gerasimenko seems like a mere speck. But Michel (@quark1972 on Twitter) shows what the comet would look like if it were gently set down in Los Angeles. I wish the city would commission a life-size replica as public art! (via io9)

Requiem for a comet

Alas, poor ISON. The comet that flew too close to the Sun on Thanksgiving Day appears to have suffered the fate of Icarus — if Icarus had been ripped apart by a solar flare. The video above, taken by space probes on the opposite side of the Sun from Earth, provides a great view of the comet hurtling toward the Sun and then disintegrating. Although there's still some discussion over whether or not ISON still survives as a much smaller ball of rock, ice, and dust, NASA has officially declared the comet dead. Astrophysicist Karl Battams wrote a very nice eulogy.

Coming tomorrow: Hot Sun-on-comet action

What happens when a solar storm collides with a comet? Back in 2007, a coronal mass ejection ripped the tail off of Comet Encke. (You can watch that happen in an awesome NASA gif.) Tomorrow, Comet ISON is due to fly closer to the Sun than Encke, during a much more active time in the solar cycle. Scientists are anticipating an awesome collision, like spectators at a demolition derby.

Weird meteor shower to peak tomorrow night

The Geminids are one of the big deal meteor showers that happen every year. In fact, they're regarded as one of the most reliable and impressive. They're also a little strange.

Most meteor showers happen when Earth and a comet cross paths, slingling rocks, dust, and debris from the comet's tail into our atmosphere. The sudden influx of shooting starts that results is a highly noticeable event and humans have been recording them for millennia.

The Geminids are different. They sort of just appeared, seemingly out of nowhere, back in 1862. And it wasn't until the 1980s that scientists were finally able to identify the thing that was producing them. At which point, ish got weirder.

That's because the object, known as 3200 Phaethon, is really confusing. It doesn't seem to be a comet. At least, not a normal, healthy, functioning comet. It doesn't even have a tail. In fact, at this point most scientists think it's probably an asteroid, which then leads to still-yet-unexplained question of where all the meteors come from. Asteroids, after all, do not typically accumulate tails of small rocks. So far, the best guess has to do with 3200 Phaethon's orbit, which over the course of about a year and a half takes it closer to the Sun than Mercury and then back out further from the Sun than Mars. Those wild temperature swings might lead to the asteroid cracking and throwing off dust and debris, which then becomes meteors. But, as a NASA info page pointed out in 2010, that explanation doesn't totally cut it.

The amount of dust 3200 Phaethon ejected during its 2009 sun-encounter added a mere 0.01% to the mass of the Geminid debris stream—not nearly enough to keep the stream replenished over time.

According to the International Meteor Organization, you can expect the Geminids to peak tomorrow night, around 5:30 pm, Central Time. But this is a big shower, so you're likely to see something even if you can't hit the exact peak.

Also: While you're watching for meteors, also keep an eye out for an upcoming feature here by Miles O'Brien, which will delve into the latest in Geminid science!

Read the 2010 NASA info page on the Geminids and an earlier NASA piece that describes a different theory for their origins.

Make use of The Bad Astronomy guide to meteor watching

Image: Geminid Meteor. Just one., a Creative Commons Attribution (2.0) image from tydence's photostream

Mark your calendar now for December 2013 comet-viewing party

Provided that the world does not end in December of 2012, you might have the opportunity to view a particularly impressive comet around Christmastime in 2013. The poetically named C/2012 S1 (ISON) will pass at a-safe-yet-great-for-viewing distance from Earth, after first passing close to the Sun — a combination that promises to produce a beautiful tail and fabulous comet-spotting opportunities, especially in the Northern Hemisphere.