How Big is Rosetta’s Comet?

...while it's one thing to say that the nucleus of Comet 67P/Churyumov-Gerasimenko is about three by five kilometers in diameter, it's quite another to see it in context with more familiar objects. Think about it—a comet as tall as Mt Fuji!

At the time of this writing Rosetta is 35 days out on approach to Comet 67P/C-G, at a distance of about 51,000 km (31,700 miles) and closing. Three "big burn" maneuvers have already been performed between May 7 and June 4 to adjust the spacecraft's course toward the incoming comet, and after smaller ones on June 18 and July 2 there are a total of five more to go. See details of Rosetta's burn maneuvers here.

As incredibly sensitive as they are, Rosetta's instruments—which were able to detect the water vapor coming from Comet 67P/C-G from a distance of over 360,000 km—have even sniffed the hydrazine exhaust from its own thruster burns.

Luckily the remaining burns are relatively small compared to the first three, with the final being very brief, so any data contamination by Rosetta's own exhaust shouldn't become an issue once the spacecraft has established orbit in August.

Launched in March 2004, ESA's Rosetta mission will be the first to orbit and land a probe on a comet, observing its composition and behavior as it makes its close approach to the Sun in 2015. Click here to see where Rosetta is right now.

Note: While 3-5 km seems pretty big (especially when stood on end) comet nuclei can be much larger, 10 to 20 km in diameter up to the enormous 40+ km size of Hale-Bopp. As comets go, 67P/C-G is fairly average. (Except that, come August, it will be the only comet with an Earthly spacecraft in tow!)

might need a spot of help on this one.

I'll help him write it.

You see, it will happen this way. The perturbations induced in Comet 67P/Churyumov-Gerasimenko's orbital path from the orbiting Rosetta craft will be amplified by the force of the lander impacting on the surface of the comet. This will cause the nucleus of the comet to grow from 5 km to huge size. The altered orbital trajectory will now cause the comet to collide with the Isonids and in turn careen the huge clouds of Isonids that miraculously did not end life on Earth as we know it their first time around into an intersecting path with Earth for another cataclysmic event.

Comet 67P/Churyumov-Gerasimenko now with a majorly modified orbit will slingshot around the sun and be massively influenced by the gravitational well of the impressive planet Mercury. This will cause the nucleus with it's NASA spacecraft on board to make a bee-line for Earth while at the same time causing Herculobus to materialize on a collision course with Niburu. NASA cameras will develop a series of 18 minute gaps in their data as Lois Learner's hard drive vainly attempts to spin away, er, up to compensate for the cover up by producing video of Michael Moore eating Venus.

The cloud of hydrazine vapors following the orbiter and lander will clone themselves and replace the atmosphere of Earth with a toxic substitute closely akin to Hillary's breath after a party. Or all the time. But I repeat myself.

And we're all gonna die.

As 'ol BP Earfbotch sez, 'Be safe out there..."

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