What term refers to all heavenly bodies and space, including our Solar system?

The term that encompasses all heavenly bodies and space, including our Solar System, is "Universe." The Universe is defined as the entirety of space and time, along with all forms of matter and energy, including galaxies, stars, planets, and the very fabric of space itself. The Universe is vast and contains billions of galaxies, each with millions or even billions of stars, along with other cosmic phenomena.

Looking at the other terms, a galaxy refers to a specific system of stars, stellar remnants, interstellar gas, dust, and dark matter, making it a smaller subset within the Universe. The cosmos is often used interchangeably with the Universe but is sometimes used to describe the ordered and harmonious aspects of the Universe rather than its entire extent. A star system refers specifically to a group of stars bound together by gravity, typically including a star and its orbiting planets, making it a much smaller scale entity than the Universe. Thus, "Universe" is the most comprehensive and technically accurate answer in this context.