In the scale of the universe, humanity is not even a speck.
This vertically oriented logarithmic map of the universe spans nearly 20 orders of magnitude and takes us from planet Earth to the edge of the visible universe. Each large “tick” on the right side of the scale corresponds to increasing the distance scale by a factor of 10.
We are each just a tiny, tiny fraction of our own planet: Earth.
The Apollo 8 astronauts were the first humans to reach a distance far enough from our planet to see the entire Earth at once. Shown here are the nearest (left) and farthest (right) images of Earth as taken by the same Hasselblad camera. Aside from the three people currently on board, all of humanity is confined to the pale, blue dot on the right.
It would take almost Avogadro’s number of people to equal the mass of the Earth.
Under ideal dark-sky conditions, the unaided human eye can see up to 6,000 stars at once, and up to 9,000 stars in total if they could see the entire sky at once, unblocked by the Earth itself. Compared to Earth, at around 6 septillion kilograms, all 8+ billion people combined are barely a drop of the total mass of planet Earth.
Earth is just one humble planet orbiting our Sun: one of ~400 billion stars in the Milky Way.
This color-coded map shows the abundance of heavy elements in more than 6 million stars in the Milky Way. The stars in red, orange and yellow are all rich enough in heavy elements that they should have planets; green and blue-green stars should rarely have planets, and blue or purple-coded stars should have no planets around them at all. Note that the central plane of the galactic disk, extending into the galactic core, has the potential for habitable rocky planets. This map shows less than 0.01% of the stars in our galaxy.
Our Milky Way is second only to Andromeda in our Local Group of galaxies.
Our local group of galaxies is dominated by Andromeda and the Milky Way, but there’s no denying that Andromeda is the largest, the Milky Way is #2, the Triangulum is #3, and the LMC is #4. Just 165,000 light-years away, it is by far the closest of the 10+ galaxies to our own, and as such occupies the largest angular spread on the sky of any galaxy outside the Milky Way. There are more than 100 galaxies in the Local Group, but Andromeda and the Milky Way contain most of the stars and also most of the matter.
Beyond the Local Group are much larger, richer, more massive groups and clusters of galaxies.
This 2014 Hubble composite image of the El Gordo Collision Cluster shows the most massive galaxy cluster ever discovered in the first half of our cosmic history. Officially known as ACT-CLJ0102-4915, it is the largest, hottest, and X-ray brightest galaxy cluster ever discovered in the distant universe, containing many thousands of times the mass of the Local Group.
Altogether, trillions of galaxies are scattered throughout the observable and expanding universe.
There are four regions in the universe that is beginning to be dominated by dark energy: one where everything in it is attainable, communicable and observable, one where everything is observable but unattainable and uncommunicable, one where things will one day be observable but not . today and the one where things will never be observable. The labeled numbers correspond to our 2024 consensus cosmology, with boundaries of 18 billion light-years, 46 billion light-years, and 61 billion light-years separating the four regions. At scales of ~10 billion light years and larger, the universe is almost perfectly uniform.
Because of dark energy, the news of humanity’s greatest deeds never reaches virtually everyone.
This 1997 artwork shows the planets of the Solar System and the relative trajectories of the first four spacecraft on course to leave the Solar System. In 1998, Voyager 1 overtook Pioneer 10, and in 2012, it passed through the heliopause and entered interstellar space. Voyager 2 entered interstellar space in 2018 and recently surpassed Pioneer 10 in 2023; therefore, we strongly suspect that Pioneer 10 is also in interstellar space, but is no longer functional, so we cannot make the critical measurements necessary to make such a determination.
And yet, from another perspective, we are truly remarkable.
30 protoplanetary disks, or proplys, as imaged by Hubble in the Orion Nebula. Hubble is a great resource for identifying these disk signatures in the optics, but has little power to probe the internal properties of these disks, even their location in space. Radio telescopes like ALMA, as well as infrared observatories like the VLT and JWST, are much better at this aspect of measuring these details. Planets mostly originate from protoplanetary disks, but different mechanisms may be responsible for different scenarios of planet formation at different distances from the parent star.
We inhabit a rocky world, formed from ancient star ash.
This concept image shows meteoroids that supply all five nucleobases found in life processes on ancient Earth. All the nucleobases used in life’s processes, A, C, G, T and U, have now been found in meteorites, along with more than 80 kinds of amino acids: far more than the 22 known to be used in meteorites. life processes here on Earth. Similar processes undoubtedly took place in star systems in most galaxies throughout cosmic history, bringing the raw materials for life to a variety of young worlds.
For approximately 4 billion years, continents and oceans persisted on Earth’s surface.
This aerial view of Grand Prismatic Spring in Yellowstone National Park is one of the most famous land-based hydrothermal features in the world. The colors are caused by different organisms living in these extreme conditions and depend on the amount of sunlight that hits different parts of the springs. Hydrothermal fields like this are some of the best candidate sites for life to have first appeared on the young Earth and may be home to abundant life on various exoplanets.
Life appeared early on Earth and has survived and flourished ever since.
This tunneling electron microscope image shows several specimens of the cyanobacteria species Prochlorococcus marinus. Each of these organisms is only about half a micron in size, but all together the cyanobacteria are largely responsible for the creation of Earth’s oxygen: both initially and largely even today. Like all bacteria, their lifespan is much, much shorter than that of humans, and even though cyanobacteria are relatively primitive organisms, they “only” date back to 2.7 billion years ago, while life on Earth has lasted for more than billions of years, at least. further than this.
Eventually multicellularity, sexual reproduction, complexity and a high level of differentiation arose.
A fascinating class of organisms known as siphonophores is itself a collection of small animals that together form a larger colonial organism. These life forms straddle the boundary between a multicellular organism and a colonial organism. The ability of individual life forms to combine traits such as multicellularity, complexity, and high levels of differentiation has led to the explosive diversity of life that has abounded on Earth over the past ~500 million years.
Inside us, an organ powers “thinking” like no other: the human brain.
This drawing shows various human, ape and ape skulls from various extant species. Older apes have less cranial capacity and smaller brains than humans, but on average much stronger jaws. For large brains to evolve, jaws had to weaken: an adaptation to loss of function. Modern humans have the highest encephalization quotient of any known animal, followed by dolphins and then, more distantly, chimpanzees and some birds.
After 13.8 billion years, civilized humans finally understood our universe.
This colorful view of the Pillars of Creation uses a large JWST data set that shows the subtle and transient nature of these neutral gas elements. Stars form in nebulae like this, but once the gas evaporates, all they can do is burn fuel until they die.
Human imagination, creativity and intelligence remain elusive.
This museum exhibit features Deep Blue: the computer that first defeated the reigning world chess champion in a chess match when he beat Garry Kasparov. Since Ruslan Ponomariov beat Fritz in 2005, no human has beaten a top-performing computer in a game of classical chess.
Maybe one day we will sufficiently appreciate our achievements.
Although many argue that the advent of quantum computing will speed up calculations across the board compared to classical computers, it is highly unlikely that this will be the case. Instead, the best computers will be hybrids: able to exploit the quantum part for applications where the Quantum Advantage can be achieved, but resort to classical computing techniques for all other (i.e. most) applications.
Mostly, Silent Monday tells an astronomical story in images, visuals and no more than 200 words.