Dust and gas
The Solar System condensed from a cloud of molecules and dust, similar to the clouds of interstellar
dust and gas observed in our Galaxy today. Discoveries over the past ten years are revealing many
similarities between dust elsewhere in the Galaxy and the composition of comets.
"When we look at dust and gas in the interstellar medium, we see molecules that are found on comets
and on Earth. They are important components for building up more complex molecules," says Pascale Ehrenfreund, an astrochemist from the
in the Netherlands and a co-investigator on ESA's Infrared
Space Observatory (ISO).
Of the 120 molecules so far detected in interstellar gas, about half are organic. "The largest
has 13 atoms (HC11N), but we think there are much larger
molecules out there," says Ehrenfreund.
ISO helped detect many of these molecules. Most notable was its finding that
water is just about
everywhere in space. In 2007, ESA's far infrared and submillimetre mission the
Herschel Space Observatory, will continue to
unravel the complexities of interstellar chemistry and further our
understanding of star formation.
"We know that our Sun formed in a similar way to other stars which are forming in front of our
eyes (or at least our telescopes) today," says Göran Pilbratt, ESA's project scientist for Herschel.
"What we don't know is to what extent planets form with these stars - and the nature of these
planets. This is a problem that must be addressed by looking for and studying planets around
already-formed stars, and by trying to understand the process of star formation itself, which
is one of the areas where Herschel is expected to have a large impact."