Astronomers have discovered some of the largest celestial objects in the universe, ranging from planets to superclusters of galaxies.
The Facts About the Largest Objects in the Universe
1. Largest Planet: ROXs 42Bb
Simulation of planet ROXs 42 Bb. (Image: NASA).
Jupiter, which is 11 times larger than Earth in radius, is the largest planet in our solar system. ROXs 42Bb is the largest planet discovered in the universe, with a mass 9 times that of Jupiter and a radius 1.12 times larger. The distance between ROXs 42Bb and Earth is 440 light-years. Being outside the solar system, it is classified as an exoplanet.
Thayne Currie, an astronomer at the University of Toronto, identified ROXs for the first time in 2013. This giant gas planet resembles Jupiter. While Earth and Jupiter take 365 days and 12 years, respectively, to orbit the Sun, ROXs 42Bb completes its orbit around its host star in 1968.3 years.
2. Largest Star: UY Scuti
Simulation of star UY Scuti. (Image: Pixabay/Pexels).
More than a million Earths could fit inside the Sun, but the largest star in the universe, UY Scuti, is so massive that it could contain 5 billion stars with a volume equivalent to that of the Sun. If UY Scuti were placed at the center of our solar system, its outer envelope would extend beyond the orbit of Jupiter. This supergiant star is located 9,500 light-years away from Earth and was first described in 1860 by a group of astronomers from the Bonn Observatory in Germany. Even 160 years after its discovery, astronomers have yet to find a star larger than UY Scuti.
UY Scuti is classified as a variable star due to fluctuations in brightness every 740 days. Scientists speculate that it is currently in a phase of exhausting hydrogen fuel in its core and expanding into a red supergiant star. This implies that it may be on the verge of a supernova explosion, marking the end of its existence. However, researchers do not yet know the exact timing of UY Scuti’s explosion.
3. Widest Star System
The widest star system in the universe, in terms of orbit, consists of a single planet (2MASS J2126) orbiting the star TYC 9486-927-1. Seven years ago, astronomers did not even know if the star and planet were related. Both were considered free-floating celestial objects as they are separated by a distance of 1,000 billion kilometers in space.
However, in 2016, an international research group identified the massive orbit of 2MASS J2126 and discovered that the planet orbits TYC 9486-927-1. The distance between Earth and this unique star system is 104 light-years. The orbit of 2MASS J2126 is 140 times wider than that of Pluto in our solar system. Aside from its extremely wide orbit and great distance from its host star, 2MASS J2126 takes nearly 900,000 Earth years to complete one orbit.
4. Largest Galaxy: IC 1101
A galaxy is a collection of many star systems. Some reports estimate that the universe contains about 2 trillion galaxies. These massive celestial objects harbor billions of stars and many other celestial bodies. For instance, the Milky Way is estimated to contain 100 billion stars and nearly 100 million black holes.
However, that number pales in comparison to IC 1101, the largest galaxy in the universe by scale. IC 1101 is 50 times larger and 2,000 times heavier than the Milky Way. Astronomers believe it is home to 100 trillion stars, spanning 6 million light-years. In contrast, the Milky Way has a diameter of only about 100,000 light-years. Some experts speculate that IC 1101 may have formed from the collision and merger of multiple galaxies.
5. Largest Black Hole: TON 618
The largest black hole in the universe is estimated to have a mass 66 billion times that of the Sun. This supermassive black hole powers a quasar (an extremely bright celestial object) named TON 618, which has a brightness equivalent to 140 trillion suns. Located 18.2 billion light-years from Earth, TON 618 was first discovered in 1957.
6. Largest Star Nursery: Tarantula Nebula
Tarantula Nebula. (Image: NASA)
Nebulae are massive clouds of gas and dust in the universe where new stars form due to the influence of gravity, changes in temperature-pressure, and nuclear reactions. The Tarantula Nebula, also known as 30 Doradus, is among the largest and brightest known nebulae, according to NASA. It spans an area of 1,800 light-years in the universe and is 170,000 light-years away from Earth. The Tarantula Nebula was discovered in the early 1750s by French astronomer Nicolas-Louis de Lacaille. However, the telescopes of that time were not advanced enough to detect individual stars and other structures within the nebula. It wasn’t until more than 200 years later that astronomers took high-resolution images of the Tarantula Nebula and realized its massive size.
7. Largest Galaxy Cluster: El Gordo
In 2012, NASA’s Chandra X-ray Observatory identified an extremely large galaxy cluster named ACT-CLJ0102-4915. When astronomers calculated its mass, they were immensely surprised. The mass of ACT-CLJ0102-4915 is estimated to be 3 trillion times that of the Sun. This is the largest galaxy cluster ever discovered, nicknamed El Gordo, which means “the fat one.”
Astronomers speculate that it may have formed from the collision of two massive galaxy clusters colliding in space at millions of kilometers per hour. El Gordo also contains the longest observable galaxy, La Flaca.
8. Largest Structure in the Universe: Hercules–Corona Borealis Great Wall
Hercules–Corona Borealis Great Wall. (Image: Pablo Carlos Budassi/Wikimedia Commons).
With a length of 6 to 18 billion light-years, the Hercules–Corona Borealis Great Wall is considered the largest observable structure in the universe. It is a cluster of galaxies bound together by gravity. The size of this supercluster is such that light takes about 10 billion years to travel the entire length of it. The Hercules Great Wall was discovered in 2013 while mapping gamma-ray bursts, the most energetic form of light.
