Dark Energy and Accelerating Expansion

Dark energy is the mysterious force driving the universe's accelerating expansion, discovered in 1998 by two independent supernova teams. It constitutes roughly 68% of the total cosmic energy budget, a fraction that makes it more dominant than #3 Discovery of Exoplanets' planetary count by orders of magnitude in terms of its universal influence. The accelerating signal was confirmed using Type Ia supernovae at redshifts above 1.0, a distance benchmark far beyond the Milky Way, and the derived deceleration parameter is negative by a margin of 0.25, 50% stronger than the threshold needed to rule out a static universe.