Particles
collected from Earth's upper atmosphere, originally deposited by comets, are
older than our Solar System, scientists say – and these fine bits of
interstellar dust could teach us about how planets and stars form from the very
beginning. These cosmic particles have lived through at least 4.6 billion years
(4,600,000,000).
And these
cosmic particles also traveled across incredible distances, according to the
new research into their chemical composition.
The international team of scientists behind this study is confident that
we're looking at the very basic materials making up the planetary bodies
currently whizzing around our Sun. For anyone studying the origins of the
Universe, it's a fantastic finding.
An x-ray
spectrometry map of the grains. (Hope Ishii/University of Hawaii; Berkeley Lab)
"The
presence of specific types of organic carbon in both the inner and outer
regions of the particles suggests the formation process occurred entirely at
low temperatures," says one of the researchers, Jim Ciston from the
Lawrence Berkeley National Laboratory. "Therefore, these interplanetary
dust particles survived from the time before formation of the planetary bodies
in the Solar System, and provide insight into the chemistry of those ancient
building blocks."
This is a
rare chance to study the material that formed our Solar System close up.
Scientists think it developed from a collapsed disk of gaseous clouds around
the Sun, but experts often have to make use of computer simulations to work out
a hypothesis.
Now, they
have their hands on dust that may have actually been there when the planets in
our Solar System were born. The amorphous silicate, carbon, and ice that was
around all those billions of years ago has largely been obliterated or reworked
into the planets we have today, with the original form of these substances now
mainly found in comets.
Rather than
catching a comet, the scientists used samples collected by a NASA stratospheric
aircraft, particles burned off comets that had eventually settled high up in
Earth's atmosphere. Using infrared light and electron microscopes, the team analyzed
the chemical composition of the particles. In particular, they looked at a
subgroup of glassy particles called GEMS (glass with embedded metal and
sulfides), measuring just a few hundred nanometers across at most - less than a
hundredth of the thickness of a human hair.
The results
showed these grains were originally fused together in an environment that was
cold and rich with radiation. Even a small amount of heat was enough to break
the bonds in the grains, suggesting they formed somewhere like the outer solar
nebula – the cloud of dust, hydrogen, helium, and other ionized gases out of
which the Solar System formed.
"The
presence of specific types of organic carbon in both the inner and outer
regions of the particles suggests the formation process occurred entirely at
low temperatures," says one of the researchers, Jim Ciston from the
Lawrence Berkeley National Laboratory. "Therefore, these interplanetary
dust particles survived from the time before formation of the planetary bodies
in the Solar System, and provide insight into the chemistry of those ancient
building blocks."
Some kind of
sticky organic material might have been responsible for these grains clumping
together, and eventually forming planets in the cold and empty early years of
the Solar System, the researchers suggest. And while it's too early to draw any
conclusions about what was going on almost 5 billion years ago, the scientists
have plans to study comet dust particles in a lot more depth, to try and unlock
the secrets of the early Solar System.
"This
is an example of research that seeks to satisfy the human urge to understand
our world's origins," says Ishii.
The research
has been published in PNAS.
Article was
originally published on ScienceAlert. Read the Original article here.