Scientists have debated the definition of life for decades, but they still lack a consensus on the answer. Experts believe that "edge cases" make life difficult to define and blur boundaries ...

But this definition of the solar system is considered to be far too simple by some astronomers, such as Caltech's Mike Brown. "It's not really true," Brown told Live Science in an email.

Historically, it’s been difficult to pin that point at a particular altitude. In the 1900s, Hungarian physicist Theodore von Kármán determined the boundary to be around 50 miles up, or roughly ...

Pioneering Planetary Boundaries science as key to mitigating rising planetary risks. ScienceDaily. Retrieved June 11, 2025 from www.sciencedaily.com / releases / 2024 / 11 / 241108113503.htm.

Together with an international team of 28 scientists, he first proposed the PB framework in 2009. "Thanks to the science of the Planetary Boundaries, we have clear evidence that there is no ...