Musings about a Comet

Mankind did a remarkable feat today: It landed a probe roughly the size of a washing machine on a comet (named 67P/Churyumov-Gerasimenko) which hurtles through space toward the sun at a speed of 40,000 miles per hour, which is more than twice as fast as the space shuttles traveled in orbit. No other man-made objects ever traveled that fast. The Apollo missions reached 25,000 miles per hour, and the Voyager spacecraft are in interstellar space now traveling at around 35,000 miles per hour.

To rendezvous with an object moving that fast, the probe has to move just as fast, and then match the orbit of the object. Scientists have likened this feat to a fly trying to land on a speeding rifle bullet. Good luck. But that is just what happened today. The European Space Agency Rosetta craft has been in space for 10 years traveling to the comet waiting for this rendezvous.

The agency published a phenomenal picture which puts the comet into perspective:

Photo credit: Matt Wang, Flickr: anosmicovni. European Space Agency

Here is the three-kilometer-wide comet sitting behind Los Angeles. How is this for size?

The asteroid that hit the earth 65 million years ago causing the extinction of the dinosaurs is estimated to have been about ten kilometers wide, or about three times this big.

Another fascinating thought is that the comet is still 317 million miles away from earth, which means that it takes radio signals 20 minutes to get here.

If the earth were the size of a tangerine (about 5 cm across), the comet would be 1.25 miles away from the tangerine and would be smaller than a speck of dust. Now we can visualize this: The Rosetta spacecraft traveled off the tangerine sized earth to hit a speck of dust one and a quarter miles away.


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