The concept of “biggest” is complex, as its definition depends on the criteria for measurement and the specific domain. Whether examining living organisms, geological formations, or celestial bodies, the scale of what is considered immense shifts dramatically. This exploration delves into various contenders for the title, moving from our familiar planet to the vast expanse of the cosmos.
Earth’s Largest Wonders
The blue whale is recognized as the largest animal by mass, reaching lengths of up to 30 meters and weighing over 100 tons. Among plants, the General Sherman Tree, a giant sequoia, holds the record for the largest tree by volume, containing an estimated 1,487 cubic meters of wood. For living organisms by area, the Pando aspen clone in Utah covers 43 hectares (106 acres) through its interconnected root system, making it a single genetic individual. A honey fungus (Armillaria ostoyae) in Oregon spans 965 hectares (2,385 acres). A seagrass meadow of Posidonia australis in Shark Bay, Western Australia, was recently identified as covering approximately 200 square kilometers (77 square miles).
Geographically, the Pacific Ocean is the largest ocean basin, covering about one-third of the Earth’s surface. Mount Everest stands as the highest mountain above sea level, while Mauna Kea in Hawaii is taller when measured from its base on the ocean floor to its summit. Humanity has also constructed colossal structures, with the Great Wall of China extending thousands of kilometers. The Grand Ethiopian Renaissance Dam, currently under construction, is designed to be one of the largest dams by volume. The Boeing Everett Factory in Washington is recognized as the largest building in the world by volume, housing the assembly of wide-body aircraft.
Colossal Objects in Our Cosmic Neighborhood
Venturing beyond Earth, our solar system contains objects of immense proportions. Jupiter is the largest planet, with a diameter approximately 11 times wider than Earth’s. It is also more than twice as massive as all other planets in the solar system combined. The Sun, our star, dominates the solar system by both size and mass, accounting for about 99.8% of the system’s total mass.
Among the numerous moons, Ganymede, orbiting Jupiter, is the largest in our solar system, even surpassing the planet Mercury in size. Pluto is now classified as a dwarf planet, and it is the second-largest dwarf planet by volume. Eris is the most massive known dwarf planet and is slightly smaller than Pluto by volume.
Giants Beyond Our Galaxy
Moving into the wider cosmos, stars and galaxies exhibit staggering dimensions. UY Scuti, a red supergiant star, was long considered one of the largest stars by radius, estimated to be around 1,700 times wider than our Sun. More recent measurements suggest its radius might be closer to 909 solar radii. Stephenson 2-18, another red supergiant, is currently estimated to have an even larger radius, approximately 2,150 times that of the Sun, though this value has some uncertainty. These stars are not necessarily the most massive, as stellar mass and physical size are distinct characteristics for evolved stars.
Galaxies themselves can be far larger than individual stars. IC 1101, a supergiant elliptical galaxy, holds the record as one of the largest known, spanning an estimated diameter of up to 4 million light-years. To put this into perspective, the Milky Way galaxy is only about 100,000 light-years across. Hercules A, another supergiant elliptical galaxy, is also remarkably large, with an estimated diameter of 1.5 million light-years. At the centers of many galaxies reside supermassive black holes, which, while incredibly dense, are measured by their immense mass rather than physical size; for instance, the one in IC 1101 is estimated to be between 40 and 70 billion solar masses.
The Ultimate Scale of the Universe
The universe organizes itself into structures far grander than single galaxies. Galaxies group together into clusters, which in turn form even larger superclusters. The Laniakea Supercluster, where our Milky Way resides, encompasses roughly 100,000 galaxies and stretches over 520 million light-years. The Shapley Supercluster, containing over 8,000 galaxies, represents a significant concentration of matter in the local universe.
These superclusters are not randomly distributed but form part of a vast, interconnected network known as the cosmic web, consisting of thread-like galaxy filaments separated by immense voids. The Sloan Great Wall, a galaxy filament discovered in 2003, measures about 1.37 billion light-years in length and is considered one of the largest structures in the observable universe. The Hercules-Corona Borealis Great Wall is an even larger grouping of galaxies, estimated to be 10 billion light-years across. The largest structure we can currently detect is the observable universe itself, which is approximately 93 billion light-years in diameter.