The Hubble Space Telescope launched in 1990 and has been humanity's most intimate eye into the cosmos. In its nearly three decades of observations, Hubble has - literally - measured the size, age, and ultimate fate of the Universe. Let's take a look at some of the most profoundly humbling images of space Hubble has ever taken, displaying the incomprehensible magnitude of our cosmic community.
Humanity exists in a brief window of cosmic history in which the Universe can be observed and studied. In a couple billion years, the accelerating expansion of the Universe will make many of the most distant objects impossible to see - forever. Civilizations that pop up in the far future may see nothing when they look up into the sky. They will have no point of reference to understand the history of the Universe, let alone its ultimate fate.
All of this has been made possible by the Hubble telescope, named after astronomer Edwin Hubble, who nearly a century ago discovered the expansion of the Universe.
Age of the Universe: ~13.7 billion years
Number of galaxies in the visible Universe: ~2 trillion
Diameter of visible Universe: ~90 billion light years, courtesy of accelerating cosmic expansion
Size of the entire Universe: unknown
Fate of the Universe: eternal expasion, cooling, and decay of fundamental particles
Why the Universe exists: unknown
What caused the Big Bang: unknown
What lies beyond the Universe: unknown
That the world watched a comet slam into Jupiter.
In 1994, a 1.2-mile-wide comet called Shoemaker-Levy 9 crashed into Jupiter, leaving Earth-sized scars as the comet, ripped apart by Jupiter's immense gravity, plunged into the Jovian atmosphere. Hubble captured the incredible event, which was broadcast live around the world.
Saturn - the crown jewel of the Solar System.The ring swirling around Saturn consists of chunks of ice and dust. Saturn itself is made of ammonia ice and methane gas. The little dark spot on Saturn is the shadow from Saturn's moon Enceladus.
Hubble snapped this picture of Saturn, the second-largest planet in our Solar System, in 1998. Saturn has some of the fastest winds in the Solar System, reaching over 1,000 miles per hour.
The Horsehead Nebula.
This infrared Hubble image of the equine-shaped cloud of gas and dust in the constellation Orion was captured in 2013. This dense fog of hydrogen and dust is 1,500 light years away and spans more than 3.2 light years from end to end.
The Pillars of Creation: a stellar nursery.
NASA released this high-resolution image of the splendorous Pillars of Creation inside the Eagle Nebula, which lies 7,000 light years away in 2015. Hubble snapped this image of these towering clouds of gas and dust, in which new stars and solar systems are forming. The clouds are more than 5 light years across. It's likely that nearby supernova explosions have caused much of the debris to dissipate over the thousands of years the light has taken to reach us.
The aftermath of the death of a star much like the Sun.
Not all stars go out with a bang. Stars with similar mass to the Sun heat up and expand, shedding their outer layers into spectacular clouds of gas and dust, forming a planetary nebula. The gas in the Butterfly Nebula pictured above has temperatures of 20,000 degrees Celsius, and is tearing through space at 950,000 kilometers per hour.
The remaining stellar core, located 3,800 light years away in the constellation Scorpius, is one of the hottest stars ever discovered, with surfaces temperatures reaching a scorching 220,000 degrees Celsius. The image above was taken in 2009.
The largest picture ever taken of our galactic neighbor, Andromeda.
This 1.5 billion pixel image is so big you'd need 600 HDTVs to see the entire thing. It was processed in 2015 and contains a staggering 100 million stars and thousands of star clusters.
Andromeda, a titanic pinwheel of a trillion stars 2 million light years away, will collide with our Milky Way galaxy in a few billion years.
A zoomable version of the image is available here. Every point of light is a star, possibly with planets and maybe even life.
A cosmic twin we will never meet.
This stunning image of the Starburst Galaxy, located 15 million light years away in the constellation Canes Venatici, was snapped in 2015. The Milky Way is thought to have a similar size and shape to this magnificent spiral stellar collection, which contains tens of billions of stars.
One day, this will be us.
These merging galaxies, observed in 1999, offer a glimpse of the future of our own galaxy's fate. In a few billion years, the Milky Way will collide with Andromeda, our nearest neighbor. Eventually, the supermassive black holes at the centers of each galaxy will merge, causing a stupendous explosion and an even bigger central bulge.
Incredibly, the distances between stars are so vast that stars rarely, if ever, crash into each other. Instead, new clusters form, while other stars are ejected into intergalactic space.
The galaxies pictured above are 110 million light years away.in the constellation Canus Major.
The first quasar ever detected.
Located 2 billion light years away, this quasar, known as 3C 273, was discovered in the 1960s, and is a real mind-bender. Quasars, or "quasi-stellar objects," are supermassive black holes at the centers of galaxes that are feeding on gas and dust.
Quasars outshine their host galaxies and shoot beams of super-heated plasma through space, reaching billions of degrees and stretching for thousands of light years. They are bright enough to be seen across the visible Universe. It is thought that a quasar will ignite when the Milky Way and Andromeda merge in the distant future.
Every point of light and smudge in the above image is an entire galaxy containing hundreds of billions, if not trillions, of stars.
The grandeur of space.
What happens when you point Hubble at an empty speck of sky and wait? This is what astronomers asked in the 1990s and again in 2004. What they saw is astonishing.
Ten thousand galaxes - some as old as 13 billion years, peppering the cosmos. Every point of light - every dot - is a galaxy. Some of them date to when the Universe was only a few hundred million years old. The redder the galaxies appear, the older and farther away they are.
The Hubble Ultra Deep Field is reveled as one of the most important and beautiful pictures ever taken.
Just how big is this chunk of the Universe? The slice of heaven Hubble stared into is about 1/10 the size of a full Moon.