How many light years in diameter is the solar system?

The solar system does not have a well-defined outer boundary, so it doesn't have a specific diameter in terms of light-years. The solar system is primarily defined by the gravitational influence of the Sun, which extends far beyond the orbit of Pluto. The region where the Sun's gravitational influence is dominant is known as the heliosphere, and it is believed to extend to about 100 astronomical units (AU) from the Sun. One AU is the average distance from the Earth to the Sun, approximately 93 million miles (150 million kilometers).

However, it's important to note that the heliosphere's boundary is not a sharp edge but rather a gradual transition, and its exact extent can vary depending on various factors. Beyond the heliosphere lies interstellar space, where the influence of the Sun's gravity becomes negligible.

Since a light-year is a unit of distance that represents the distance light travels in one year (approximately 5.88 trillion miles or 9.46 trillion kilometers), the solar system is much smaller than a single light-year in diameter. The nearest star system, Alpha Centauri, is over 4 light-years away from the Sun, for reference.