*2.3.2 Neptune Class*

*Solar System Planets and Exoplanets*

unconfirmed.

*2.2.4 Meteorites*

planet's atmosphere [15].

**2.3 Exoplanetary Systems**

also possible [8].

*2.3.1 Gas Giants*

harm including impacts on the climate.

cyanide, methane, ammonia, and acetylene [34].

methods is presented in subsequent discussion.

Ref. [12] performed numerical simulations to fit the observed orbits. A perturbing body (Planet Nine) was incorporated in the simulation to reproduce the observed orbital characteristics of a number of Kuiper Belt Objects. The simulations [12] suggest that the object perturbing the orbits is a "primordial giant planet core that was ejected during the nebular epoch of the Solar System's evolution". At the present time, the existence of Planet Nine is

The collision of asteroids produces a collection of smaller objects known as meteoroids. These collisions produce trajectories governed by the gravitational interaction of Solar System bodies. When a meteoroid enters the atmosphere of a planet, it is heated by friction and becomes a meteor. If the meteor strikes the

Meteorite material is also produced by the fracturing of comets that are exposed to the increased heat of the Sun particularly in the vicinity of the inner Solar System planets. These occurrences often lead to showers of micrometeorites that impact a

Meteorites play a key role in planetary development. By depositing chemical elements or prebiotic material, meteorites can influence the evolution of a plant during its formative years. The extent of this influence depends on their size, frequency of impact, and composition. Meteorites striking a mature planet can cause ecological

Exoplanets are planets that orbit stars outside the Solar System. Given the diversity of star types and sizes, exoplanets have a wider range of physical characteristics than the planets that inhabit the Solar System. The various types of exoplanets include the most massive or gas giant planets, intermediate mass or Neptune planets, and low mass planets that include terrestrial and ocean planets or water worlds [9, 26]. Although most exoplanets orbit their host stars, rogue exoplanets are

Gas giant exoplanets are similar to Jupiter and Saturn. Their composition is dominated by hydrogen and helium with smaller contributions from heavier elements and complex molecules. Their structures may include cores of rock or ice [9, 15, 26]. However, a recent publication suggests that hot Jupiters could exhibit a more diverse chemical composition [34]. For example, an analysis of HD 209458b atmospheric data suggests the presence of water, carbon monoxide, hydrogen

Hot Jupiters are a classification of gas giants that typically reside near their star usually within 0.05 to 0.5 AU [23]. They could have formed near their host star or migrated toward the star after forming at a more distant location. Given the proximity to their host star, temperatures can exceed 2,000 K [23]. Considering their size and proximity to their host star, they are readily detected and are one of the most common types of exoplanet detected to date. A commentary of detection

planet's surface, its surviving fragments are called meteorites [15].

**16**

Exoplanets known as the Neptune class are also giant planets, but heavy elements comprise most of their mass [9, 26]. The Neptune class of exoplanets has a thick hydrogen and helium layer, but these elements are not the dominant constituents as they were in the gas giants. Within the Solar System, both Uranus and Neptune are representative of this class of planets.

Uranus and Neptune are Solar System analogues of Neptune class exoplanets. These systems have a characteristic blue color. They are also known as ice giants because many models suggest that the bulk of the planet's mass resides within a sea that probably is comprised of ammonia, methane, and water [9]. However, there is likely a significant diversity in the composition of Neptune class exoplanets.
