Our Solar System
Our solar system is a relatively small part of the Milky Way galaxy, yet it provides a wealth of information about planetary formation, dynamics, and the conditions necessary for life. Formed roughly 4.6 billion years ago, the solar system’s structure and the nature of its planets and smaller objects offer key insights into planetary science.
The Sun
The Sun is a G-type main-sequence star (G2V) that dominates the solar system, containing over 99% of its mass. Energy is produced in the Sun’s core through nuclear fusion, where hydrogen nuclei combine to form helium. This energy radiates outward, fueling the solar wind and driving space weather.
Planetary Formation
The leading theory of planetary formation, known as the Nebular Hypothesis, suggests that planets formed from a rotating disk of gas and dust surrounding the young Sun. This process begins with small particles sticking together to form larger bodies, called planetesimals, which then collide and merge to form planets.
Beyond the planets, the solar system contains smaller bodies:
- Asteroids: Primarily found in the asteroid belt between Mars and Jupiter, they are remnants of early planetesimals.
- Comets: Icy bodies originating from the Kuiper Belt and Oort Cloud. They develop characteristic tails when they approach the Sun.
Habitability and Life
Earth is the only planet known to support life, largely due to its location in the habitable zone—the region around a star where temperatures allow liquid water to exist. The search for life on other planets, both within and outside our solar system, is central to modern astronomy and astrobiology.