A Sudden Jet on Comet 67P
			
		
		
		
			There she blows!  
A dramatic demonstration of how short-lived some comet jets can be was documented in late July by the 
robotic Rosetta spacecraft orbiting the nucleus of Comet 
67P/Churyumov-Gerasimenko.
The featured animation 
depicts changes in the rotating comet with 
three illuminating stills. 
Although the first frame shows nothing unusual, the second frame shows a sudden strong jet shooting off the 
67P's surface only 20 minutes later, while the third frame -- taken 20 minutes after that -- shows but a slight remnant of the once-active 
jet.
As comets near the Sun, they can produce 
long and beautiful tails that stream across the inner Solar System. 
How comet 
jets produce these tails is a topic of research -- helped by images like this.
Another recent 
Rosetta measurement indicates that the 
water on Earth 
could not have come from comets like 
67P because of significant differences in impurities.  
Comet 67P spans about four kilometers, orbits the Sun between Earth and Jupiter, and has been the home for 
ESA's Rosetta 
spaceship since 2014 August.
Rosetta is 
currently scheduled to make a 
slow crash 
onto Comet 67P's surface in late 2016.