17 pictures that show how mind-bogglingly large the Universe is
Our entire planet is little under 13,000 kilometers in diameter, or almost seven orders of magnitude larger than the size of a human. But as we go up, to larger and larger scales, we find that stars, stellar systems, star clusters, galaxies, clusters of galaxies, and more show us how insignificant human, and even planetary, scales truly are. Even with everything we know, the vast abyss of the unobservable Universe is larger than the sum of everything we can see. These images demonstrate how enormous the cosmic scale truly is.
The two main islands on the southern section of the Mascarene Plateau are shown in this photograph shot from the International Space Station by astronaut Karen Nyberg in 2013: Réunion, in the foreground, and Mauritius, which is partially obscured by clouds. A telescope the size of Hubble would be needed to see a human on Earth from the altitude of the ISS. A human is less than 1/5,000,000 the size of the Earth, yet the Earth is but a drop in the cosmic ocean. (Credit: NASA/Karen Nyberg)
All humanity has ever known is confined within a spheroid only 13,000 km across.
This image of Earth was provided by NASA’s MESSENGER spacecraft, which had to perform flybys of Earth and Venus in order to lose enough energy to reach its final destination: Mercury. The round, rotating Earth and its properties are undeniable, as its rotation explains why the Earth bulges at the center, is compressed at the poles, and has varying equatorial and polar diameters. Still, the average diameter of the Earth is slightly less than 13,000 kilometers, with variations in the polar and equatorial directions of less than 1%. (Credit: NASA/MESSENGER)
Other planets routinely have thousands of times the volume of Earth.
The Solar System’s planets are depicted to scale in terms of their physical sizes, but not in terms of the distances between them. Jupiter and Saturn are both more than ten times the diameter of Earth, and other big planets can grow to be twice the size of Jupiter. (Credit: NASA/Lunar and Planetary Institute)
Stars begin as small as the largest planets, but get much larger.
Brown dwarfs with masses ranging from 0.013 to 0.080 solar masses may fuse deuterium+deuterium into helium-3 or tritium, remaining roughly the same size as Jupiter but gaining much greater masses. Red dwarfs are just slightly larger, but Sun-like stars, which are several times larger, are not shown to scale. (Credit: NASA/JPL-Caltech/UCB)
The biggest supergiant stars have diameters exceeding billions of kilometers.
This illustration depicts some of the greatest stars in the Universe, as well as Saturn’s (brown ellipse) and Neptune’s (blue ellipse) orbits for comparison. From left to right, the stars are the largest blue hypergiant, yellow hypergiant, orange hypergiant, and the two largest stars of all: UY Scuti and Stephenson 2-18. The biggest stars have a diameter 2,000 times that of our Sun. (Credit: SkyFlubbler/Wikimedia Commons)
They have the same size as the most massive black hole event horizons.
The relative sizes of the event horizons of the two supermassive black holes orbiting each other in the OJ 287 system are seen in this diagram. The larger one, with 18 billion solar masses, is 12 times the size of Neptune’s orbit; the smaller one, with 150 million sun masses, is nearly the size of Ceres’ orbit around the Sun. There are only a few galaxies with supermassive black holes that are “only” 4 million solar masses in size, all of which are far smaller than our own. (Credit: NASA/JPL-Caltech/R. Hurt (IPAC))
But even the largest individual objects are no match for cosmic collections of objects.
When viewed on a logarithmic scale, the solar system shows how far away some of the objects are. The planets, the Kuiper belt, the Oort cloud, and the nearest star are all depicted, along with Voyager 1, our most distant artificial spacecraft, which is now 155.5 AU from the Sun. (Credit: NASA/JPL-Caltech)
The Oort clouds extend for tens of billions of kilometers around each star system.
An illustration of our Sun’s inner and outer Oort Clouds. The inner Oort Cloud is shaped like a torus, but the outer Oort Cloud is spherical. The true extent of the outer Oort Cloud may be under 1 light-year, or greater than 3 light-years; there is a tremendous uncertainty here. The aphelion of Comet Bernardinelli-Bernstein is just under one light-year, implying that the Oort cloud is at least that vast. (Credit: Pablo Carlos Budassi/Wikimedia Commons)
The stars themselves cluster into vast galactic assemblages.
There are only about 1000 stars in the entire dwarf galaxies Segue 1 and Segue 3, which have a gravitational mass of 600,000 suns. The dwarf satellite Segue 1’s stars are circled here. As scientists locate smaller, fainter galaxies with fewer stars, we realize how frequent these small galaxies are; there could be up to 100 in our Local Group alone. (Credit: Marla Geha/Keck Observatory)
At minimum, they possess thousands of stars, spanning hundreds of light-years.
Abell 2029 is a giant galaxy cluster that contains the galaxy IC 1101. At 5.5-to-6.0 million light-years across, over 100 trillion stars and the mass of nearly a quadrillion suns, it’s the largest known galaxy of many metrics. Due to the Universe’s finite age and the presence of dark energy, it is extremely difficult for it to make a single object significantly larger. (Credit: Digitized Sky Survey 2; NASA)
The largest galaxies contain over 100 trillion stars, with record-breaking Alcyoneus spanning an unprecedented 16 million light-years.
The scale of galaxies, including the Milky Way, Andromeda, the largest spiral (UGC 2885), the largest elliptical (IC 1101), and the largest radio galaxy, Alcyoneus, are all depicted together and accurately to scale in a first-of-its-kind image. (Credit: E. Siegel)
Galaxies cluster together on even larger scales, generating formations hundreds of millions of light-years across.
The massive galaxy cluster MACS J1149.5+223, whose light took almost 5 billion years to reach us, is one of the Universe’s largest bound structures. On larger scales, nearby galaxies, groups, and clusters may appear to be associated with it, but are being driven apart by dark energy; superclusters are only visible structures, but the largest galaxy clusters that are bound can still reach hundreds of millions, if not billions, of light-years in extent. (Credit: NASA, ESA, and S. Rodney (JHU) and the FrontierSN team; T. Treu (UCLA), P. Kelly (UC Berkeley), and the GLASS team; J. Lotz (STScI) and the Frontier Fields team; M. Postman (STScI) and the CLASH team; and Z. Levay (STScI))
Although not gravitationally bound, the largest superclusters, voids, and filaments extend for billions of light-years.
At 1.37 billion light-years across, the Sloan Great Wall is one of the Universe’s greatest apparent, though transient, structures. It may just be a chance alignment of multiple superclusters, but it’s definitely not a single, gravitationally bound structure. The Sloan Great Wall galaxies are pictured at right. (Credit: Willem Schaap (L); Pablo Carlos Budassi (R)/Wikimedia Commons)
Our visible Universe is 92 billion light-years across.
The size of our visible Universe (yellow), along with the amount we can reach (magenta) if we left, today, on a journey at the speed of light. The visible Universe has a limit of 46.1 billion light-years because that is how far away an entity that emitted light that is only now reaching us would be after expanding away from us for 13.8 billion years. The yellow sphere illustrated here contains an estimated 2 trillion galaxies, but that estimate is likely to be low, probably by a ratio of 3 to 10.(Credit: Andrew Z. Colvin and Frederic Michel, Wikimedia Commons; Annotations: E. Siegel)
However, the unobservable Universe must be hundreds of times larger.
This simulation depicts the cosmic web of dark matter as well as the large-scale structure it generates. Normal matter is present, but is only 1/6th of the total matter. Meanwhile, matter itself only composes about 2/3rds of the entire Universe, with dark energy making up the rest. Our 92 billion light-year diameter Universe is less than one-64-millionth of the minimum volume of what’s out there since the unobservable Universe must extend at least 400 times the extent of the visible Universe. (Credit: The Millennium Simulation, V. Springel et al.)
For all we know, the Universe may even be infinite.
While it is predicted that many independent Universes will be produced in an inflating spacetime, inflation never ends everywhere at once, but rather only in distinct, independent areas separated by space that continues to inflate. This is the scientific justification for a Multiverse, why no two Universes will ever collide, and why we fully expect the unobservable Universe to grow to an infinite size over time. (Credit: MUSTAFABULENT / Adobe Stock)
