Cosmochemistry- Meteorites and Comets
The matter we observe in this vast
seemingly endless universe we live in is completely made of the elements we
have all seen in the modern periodic table. Cosmochemistry is the subject that
deals with the study of chemical makeup of the matter we find in the universe
along with the processes that led to that specific composition. This discipline
of science contributes a lot towards humanity's understanding of the universe,
origin of universe and matter as we know it which is crucial for the
advancement of the human civilization. The chief area of study in this subject
are meteorites and comets.
Meteorites are pieces of
extra-terrestrial rocks that have fallen to the Earth. These rocks are mostly
remnants of asteroids or comets. Asteroids themselves are considered to be the
remnants of the protoplanetary disk that didn’t form a planet. Cosmochemistry
involves studying the chemical composition of these meteorites. This provides
researchers insight about the conditions that existed in the solar nebula, the
cloud of gas and dust that gave rise to the solar system which we are a part
of.
Meteorites are broadly classified as
– stony, stony-iron, iron. Stony meteorite are predominantly made up of
silicate minerals and also known as chondrites. Iron meteorites also known as
siderites are made up of mainly iron and nickel. As the name suggests stony
iron meteorites or siderolites are made up of both silicates and iron/nickel. The
composition of meteorites gives an idea about its origin. For example stony
meteorites are thought to have originated from the outer regions of the solar nebula
while iron meteorites are considered to be formed from the core of an asteroid.
By studying the isotopic ratios of certain elements, researchers can determine
the age of our solar system and about the process of formation of planets from
protoplanets.
Comets are basically icy bodies
composed of ice, dust and small rocks. They originate from the outer solar
system. They have highly elliptical orbits which take them closer to the sun
and then swing them back to far reaches of the solar system. Thanks to this
eccentric orbit, when the comet reaches near the sun it glows and the cloud of
gas it gives off forms a tail which we are able to witness clearly in the night
sky. By studying the composition of this tail, we are able to study the
chemical makeup of the comet and the processes that occur when it interacts
with the solar wind.
Comets are remnants of the early
solar system which are relatively untouched since their origin 4.5 billion years
ago. By analyzing them we can learn about the conditions that prevailed in the
outer solar system during the formation of planets. We are all aware about the
prominent Halley’s comet, which is visible from earth every 76 years. It is
named after Edmund Halley, who predicted its return based on observations of it
made in 1531 and 1607. It is thought to have originated from the Kuiper Belt.
Kuiper belt is a ring of icy objects around the sun beyond the orbit of
Neptune, which is thought to be the source of many short period comets. The
importance of studying comets can be understood by the efforts scientists put
to study them, like the Rosetta and Philae mission. This mission involve
landing a craft named Philae on comet Churyumov-Gerasimenko’s nucleus to collect
data about the comets composition.
To conclude, Cosmochemistry is an
interesting and crucial field of study that provides key information regarding
the origin of the universe and the solar system. Main objectives of this field
is to find the abundances of the elements in the solar system. Meteorites and
comets are the keys to unlocking this information. By studying this scientists
can gain vital information to answer the mysteries of our universe and origins
of life on earth.
