Ocean Origins on Earth - Ocean Worlds: The Story of Seas on Earth and Other Planets - page 25

at very high temperatures. Thus, not all cometary material was born
in the cold outer reaches of the solar system: at least some included
minerals made close to the Sun and then flung outwards. This sug-
gested a very dynamic—and therefore physically and chemically
complex—early solar system.
Then, in late 2010, the Herschel Space Observatory (see Chapter 1)
turned its keen gaze on to a passing comet, named 103p/Hartley 2
(Fig. 3), and obtained, as its researchers put it, 'exquisite spectra' of the
fig. 3. Comet Hartley 2, captured by NASA's EPOX I mission between 3 and 4
November 2010. The water content of this comet has a deuterium value very
similar to that of the Earth's oceans, showing that comets could represent a
potential source of the water on Earth.