How might comets and asteroids have contributed to the origin of life on Earth?

Comets are fascinating celestial bodies that originate from the outer regions of our solar system. They are often described as 'dirty snowballs' because they are composed of ice, dust, and rocky material. A key feature of comets is their long, glowing tails, which develop when they get close to the Sun and the heat causes the ice to vaporize.
Comets are thought to contain a variety of organic compounds, including complex carbon-based molecules.
When these comets collide with planets or moons, they have the potential to deliver water and organic molecules, setting the stage for the development of life. These impacts would have played a fundamental role in shaping the early Earth, contributing essential ingredients needed for life's complex chemistry.

Asteroids are rocky bodies that primarily reside in the asteroid belt between Mars and Jupiter. Unlike comets, which are icy, asteroids are composed mostly of rock and metal. They vary significantly in size, from small pebbles to objects that are hundreds of kilometers in diameter.
Just like comets, asteroids can carry organic molecules and water. When asteroids collide with Earth, they can deliver these crucial components. Scientists believe that such impacts were more frequent during the early stages of our planet’s history, helping to form oceans and potentially creating a favorable environment for life to emerge.
Asteroids' role in the origin of life is supported by the presence of organic molecules found on meteorites (fragments of asteroids that reach Earth).

Organic molecules are carbon-based compounds that are the building blocks of life. They include simple molecules like amino acids and more complex ones like nucleotides.
Organic molecules can combine to form larger structures such as proteins and nucleic acids, which are essential for all known forms of life. The delivery of these molecules to early Earth by comets and asteroids is significant as it may have provided the necessary ingredients for prebiotic chemistry.
The presence of organic molecules on comets and asteroids suggests that simple life-related chemistry is widespread in the solar system, and perhaps even in the galaxy.

Prebiotic Earth refers to the condition of our planet before the emergence of life. During this time, Earth had different atmospheres and environmental conditions, which are believed to have been favorable for chemical reactions that led to life.
The delivery of water and organic molecules by comet and asteroid impacts helped create an environment rich in the chemical diversity needed for the origin of life.
Conditions on prebiotic Earth allowed for complex chemical reactions leading to the formation of more complex organic structures, which eventually gave rise to biological systems.

The Miller-Urey experiment, conducted in 1952, was a landmark scientific experiment that demonstrated that organic molecules could be synthesized from simple inorganic compounds under conditions thought to be similar to those on prebiotic Earth.
In the experiment, Stanley Miller and Harold Urey simulated early Earth’s atmosphere by mixing water, methane, ammonia, and hydrogen in a closed system and applying electrical sparks to mimic lightning.
The experiment resulted in the formation of amino acids and other organic molecules, providing strong evidence that the building blocks of life could form under natural conditions.
The Miller-Urey experiment supports the idea that comets and asteroids could have delivered the necessary organic molecules to early Earth, where they underwent further chemical reactions facilitated by the planet's prebiotic environment.