Standing next to the pyramids, one cannot help but marvel at their size. The Burj Dubai, standing over a half mile tall, is equally stunning as it rises into the clouds. Towering above them both is the monstrous, and often deadly, Mt. Everest.

Yet, compared to some of the things that exist in our universe, they are absolutely microscopic. Today, we will explore the largest things in the universe based on their relative sizes.

11. Largest Asteroid

Ceres is the largest asteroid we’ve discovered so far. It contains 1/3rd the mass of the entire asteroid belt and is almost 600 miles in diameter. It’s about the size of California and is massive enough that its own gravity forces it into a spherical shape. It’s so large that it also has earned the title of ‘Dwarf Planet’. It’s the only object in the asteroid belt big enough to earn the designation.

10. Largest Planet

Located in the constellation Hercules, planet TRES4 is 70% larger than Jupiter in diameter, but has only 80% of Jupiter’s mass. Because of how close it orbits to its sun, it is thought that the intense heat expand the gasses that make up this planet, resulting in an almost ‘marshmallow-like’ density. It holds the title of the largest planet we’ve discovered so far.

Update: Science is never finished. Since this list was compiled, observations of an exoplanet called WASP-17b suggest that it is even bigger than TRES4. Despite its radius being twice that of Jupiter’s, it only has half the mass. This makes it even “fluffier” than TRES4.

9. Largest Star

VY Canis Majoris is the largest star (in diameter) that we know of. It’s in a class of star known as Red Hyper Giants. It’s 1,420 times the sun’s radius and would take the world’s fastest race car 2,600 years to circle it once. If you replaced our Sun with VY Canis Majoris, its surface would extend out beyond Saturn. (see picture to the right for comparison to our own sun).

Update: In 2013, NML Cygni was verified as the largest known star. It’s a whopping 1,650 times our sun’s radius. That is so large; it would take a beam of light 6 hours and 40 minutes to circle it once.

2nd Update: Science continues to astound us! Now beating out NML Cygni, UY Scuti is the leading candidate for the largest star ever discovered. At 1,708 times our suns radius, if the earth was the size of a basketball, UY Scuti would be 125,000 feet tall!

8. Largest Black Hole

Black holes are not physically large regions of space. But when you include their mass, they are among the top competitors for the largest things in the universe. And quasar OJ287 is the largest black hole we’ve spotted.< It’s estimated to be 18 billion times the mass of our sun and is a supermassive black hole located in the center of a galaxy. To put that in perspective, it’s an object larger than our entire solar system. Just how big can a black hole get? According to scientists, there is no theoretical upper limit.

Update: 11/28/2012 – Science never fails to keep impressing us with its newest discoveries. Researchers at the University of Texas, using the Hobby-Eberly Telescope, have discovered what they claim to be the largest supermassive black hole yet. The black hole, a whopping 17 billion solar masses, resides at the center of galaxy NGC 1277. That is so huge, it accounts for 14% of the entire galaxy’s mass. The event horizon is 11x the diameter of Neptune’s orbit around our sun – that’s a radius of over 300 AU.

7. Largest Galaxy



A super galaxy is a galaxy that has merged with many others and they sit in the middle of galaxy clusters. The largest that we’ve discovered so far is the IC1101 super galaxy. It is 6 million light years across. Compare that to the Milky Way which is a mere 100 thousand light years across. IC1101 is a staggering 60 times larger than our own.

6. Radio Lobes

Radio lobes are powered by the accretion disk of supermassive black holes. These supermassive black holes can be found at the center of most galaxies. As material gets consumed by a black hole, some energy and matter is flung away at high speeds which occur at the poles of black holes.

These emissions are in the form of radio energy jets which can be seen with a radio telescope. The largest is located in the galaxy is 3C236 which is located in the constellation Leo Minor. Its jets span 40 million light years across. The jets from end to end are by far larger than any galaxy.

5. Lyman Alpha Blobs

These blobs are a very short lived phase of the birth of galaxy clusters. They are amorphous objects filled with gas that haven’t fully coalesced and are not bound or set gravitationally yet. As these blobs age, they will condense and eventually form giant collections of galaxies.

Lyman Alpha blobs resemble amoebas or jellyfish in shape. The largest one that we have spotted is 200 million light years wide and is located in the constellation Aquarius.

4. Shapley Super Cluster

The Shapley supercluster is a collection of galaxies some 400+ million light years long. Our own Milky Way galaxy is roughly 4,000 times smaller. The supercluster is so big, that our fastest spacecraft would spend trillions of years trying to cross it.

It is the most massive gravitationally bound object that we currently know of. Being gravitationally bound means that as the universe continues to expand, the gravity between the galaxies in this cluster are strong enough overcome that expansion, keeping them together forever.

3. KBC Void / The Boötes Void

Galaxies usually reside in clusters. These clusters are lightly gravitationally bound and expanding along with space/time itself in groups.

But what about the areas where these groups do not reside? Enter the Boötes Void. This region of “nothingness” is a whopping 250 million light years across. That’s 2,500 milky way galaxies placed side by side. Voids are like holes in our universe, and the Boötes Void is the largest. While these voids are not totally empty, and some galaxies do reside within them, they contain significantly less matter than the rest of the universe.

Update 2/2/2017: Astronomers have recently discovered 2 voids that are significantly larger than the Boötes Void. The first is known as the Canes Venatici Supervoid (or just “Giant Void”). This void is 1.3 billion light years across. The second is the largest void we have discovered thus far. You’d be quite shocked to learn that the Milky Way and our local group reside within this void. It’s called the KBC Void and it measures in at a massive 2 billion light years.





2. The Huge-LQG

Discovered in January of 2013, the Huge-LGQ (Huge Large Quasar Group) is said to be the largest structure in the universe. The Huge-LQG is a collection of 73 confirmed quasars (a quasar is a very energetic galaxy). Astronomers discovered that the group of gravitationally bound quasars is so large that it would take over 4 billion years to traverse from end to end – while traveling at light speed.

It’s so big, that its very existence puts it at odds with Einstein’s Cosmological Principle. The cosmological principle says that, when looking at the universe from a large enough scale, it should look the exact same no matter where you are observing from, or where you look. The Huge-LGQ throws a wrench into that assumption. Researchers are understandably fascinated by the discovery and are eager to continue their investigations.

1. The Cosmic Web

Most astronomers agree that the biggest thing in the universe is the cosmic web. It’s an endless scaffolding of galaxy clusters surrounded by dark matter and resembles a three dimensional spiderweb. Clusters of galaxies and dark matter make up “hubs” and filaments of galaxies connect these hubs producing a web like appearance. (see side picture)

How big is the web? If the Milky Way galaxy was a poppy seed, then the cosmic web of the observable universe would be the size of the Rose Bowl stadium.

Photos by NASA and Wikicommons and are available under a Creative Commons Attribution license