The Water Wonders of Our Solar System: Comets

By Afreen Hossain and Rudra Sekhri

Comets, those radiant wonders of the Solar System, take the stage as another captivating species of space rock. Just like their asteroid counterparts, these cosmic gems possess their own unique charm and brilliance.

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Comets are like celestial beacons, casting their mesmerising glow across the vastness of space. Some of these celestial travelers are so small in size that they remain elusive even when observed through the lens of a telescope from Earth. Their brilliance may be diminutive, but their cosmic allure is simply awe-inspiring.

These celestial wonders possess a truly remarkable composition. Deep within their core, comets harbour an icy heart, making them icy bodies at their core. Moreover comets are a cosmic cocktail of various elements. In addition to their icy composition, they are also composed of metals and rocks, creating a unique blend of cosmic materials.

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Now, here's the twist: comets have a distinct layer of black dust on their surfaces, giving them a charming nickname – the "dirty snowballs" of the cosmos!

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As these celestial objects journey closer to the radiant embrace of the Sun, a remarkable transformation takes place. They gradually melt, transforming into a gaseous state. The dust particles released in this process create a magnificent cloud known as a coma, which forms a radiant head at the forefront of the comet. And here's the astonishing part: the Sun's rays illuminate this coma, sometimes allowing it to be visible even from our Earthly vantage point!?

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These cosmic wanderers primarily hail from two distinct regions of our solar system. First, we have the Kuiper Belt, a cosmic neighbourhood located just beyond the orbit of Neptune. And second, we venture even further to the outer reaches of the solar system, where the Oort Cloud resides, marking the boundary of our cosmic realm.

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Within the realm of comets, we encounter two fascinating types: short-period comets and long-period comets. Short-period comets complete their orbit around the Sun in less than 200 years. One famous example is the iconic Halley's Comet, gracing our skies once every 76 years. Its last appearance dazzled stargazers in 1986, and it’s anticipated that its next visit will be in 2061. Another extraordinary short-period comet is Encke's Comet, holding the record for the shortest-known orbit of any comet. It completes its journey around the Sun every 3.3 years. Both Halley's Comet and Encke's Comet originate from the Kuiper Belt.?

Long-period comets embark on an extraordinary journey, with orbits lasting more than 200 years. But wait, there's more! Some of these cosmic wanderers demonstrate an even greater cosmic endurance, with orbits stretching beyond a whopping 1000 years.

The outermost reaches of our solar system, where the magnificent Oort Cloud reigns supreme. It is within this vast and distant realm that the origins of long-period comets can be traced.

Comets hold particular promise as transporters for the organic molecules necessary for abiogenesis, or the formation of life from organic molecules on any given planet. The idea of panspermia is an explanation of abiogenesis by which either fully assembled cells could’ve originated from asteroids and/or comets.

While that hasn’t been proven yet, comets did indeed play a role in the formation of Earth’s oceans, as well as the transportation of the organic building blocks that form life.

It’s why we’re so interested in studying comets, because they reveal a lot about the Solar System’s past, just like asteroids, and the mechanisms by which life could’ve arose on Earth.