Space Physics and Astrophysics - SS2 Physics Past Questions and Answers - page 2

The Solar System formed approximately 4.6 billion years ago from a giant molecular cloud. Gravity caused the cloud to collapse, forming a spinning disk. The Sun formed at the centre, while the remaining material in the disk coalesced to form planets, moons, asteroids, and comets. Over time, the planets underwent processes like differentiation, where denser materials sank to the core, and impacts from debris shaped their surfaces. The Solar System continues to evolve, with ongoing studies of its components and their interactions.

Terrestrial planets, including Mercury, Venus, Earth, and Mars, are rocky planets with solid surfaces. They have relatively high densities and lack extensive atmospheres compared to gas giants. Gas giants, such as Jupiter and Saturn, are composed primarily of hydrogen and helium, with a smaller amount of heavier elements. They have thick atmospheres and lack a well-defined solid surface. Gas giants also have a higher number of moons and a more prominent ring system compared to terrestrial planets.

The asteroid belt is a region located between the orbits of Mars and Jupiter, where numerous small rocky objects called asteroids orbit the Sun. These asteroids range in size from small boulders to dwarf planets like Ceres. The asteroid belt is significant as it provides insights into the early history of the Solar System and the processes involved in planet formation. It is also a source of meteorites that occasionally reach Earth.

Planetary moons are natural satellites that orbit planets in the Solar System. They vary in size, composition, and surface features. Moons can have diverse geological processes, including volcanism, tectonic activity, and erosion. They play crucial roles in shaping the planetary environment through their gravitational interactions. Moons also serve as targets for scientific exploration and potential sites for future human missions.

Space exploration missions have greatly contributed to our understanding of the Solar System. The Voyager missions provided valuable data and images of the outer planets, their moons, and the interstellar medium. The Mars rovers, including Curiosity and Perseverance, have explored the Martian surface, providing insights into the planet's geology, climate, and potential for past or present habitability. These missions have expanded our knowledge of planetary processes and paved the way for future exploration.