Our ancestors millennia ago obviously didn't have the technology and resources we have today to explore our universe and beyond. Thus, many astronomy enthusiasts ages ago spent their nights looking up at the sky, theorizing and telling tales about the heavens above. Unbeknownst to them, what was really happening light years away was more transcendent than even the most adventurous stories they could have imagined.
Over the past 50 years, NASA has opened the doors for space exploration through their exquisite state of the art telescopes and probes that allow us to observe the perplexities of space. The only way we are able to view the universe is through the photographs released by NASA, unless of course you're one of the fortunate people who can afford a ticket to space with Virgin Galactic.
It's important to recognize that compiling a list of just 20 photos out of the hundreds of thousands available is inherently subjective. The photos below have been chosen based on some of the most breathtaking pictures taken through satellite imaging, planetary exploration and spaceflight. If you feel like we missed some great ones, go ahead and post them in the comments section below.
Here is our list of NASA's 20 most striking photos:
20 Hubble Extreme Deep Field
Hubble was used in its early stages to produce a Deep Field image located in a small region in the constellation Ursa Major. In recent years, NASA has generated a new version of this image called the Hubble Extreme Deep Field, which was created from 2000 snapshots of what appeared to be an empty area of sky in just two million seconds. Every pixel, smudge, swirl and every point of light seen in this image is an entire galaxy. Just take a minute to absorb that. Billions upon billions of stars have been compacted into a single pixel in this image.
19 Chaos in the Heart of Orion
The Spitzer and Hubble Space Telescopes together show the chaos of infant stars about 1,500 light-years away in the heart of the Orion Nebula. It is also our closest known massive star formation, and astronomers believe it may very well hold more than 1,000 young stars. The image shows a cluster of newborn stars scattered throughout the cloud. The Orion Nebula is the brightest spot in the sword of Orion, also known as the "hunter" constellation.
18 Yuri's Space Walk
Any time an astronaut gets out of a vehicle while in space, it's called a spacewalk. On September 11th, 2000 Cosmonaut Yuri l. Malenchenko, a mission specialist, was caught on camera during his spacewalk, bestowing upon us this breathtaking image. He and astronaut Edward T. Lu spent over 6 hours that day on their spacewalk, performing tasks on the exterior of the International Space Station (ISS).
17 Eye of God
The Helix Nebula, also known as the Eye of God, lies approximately 650 light years away towards the constellation of Aquarius and stretches about 2.5 light years. The inner edge of the Helix Nebula shows composite gas knots of unidentified elements. The picture is a combined image from both the Hubble Space Telescope and wide-angle images from the Mosaic Camera from Kitt Peak National Observatory.
16 Rosette Nebula
The Rosette Nebula is a massive, spheroid region located near a giant molecular cloud in the Monoceros area of the Milky Way galaxy about 5,200 light years away from Earth. It's enormous, and covers more than six times the area of the full moon. As shown in the image above, the Rosette Nebula is a prominent star-formation region that glows as a result of ultraviolet radiation from young, hot, blue stars whose winds are inevitably cleared at its core.
15 Hercules A - Black Hole
At first sight, Hercules A is a typical oblong galaxy, but what makes it unique is that its core consists of a black hole so massive that it makes our galaxy look paltry in comparison. Hercules A is located just over 2 billion light years away from our own Milky Way, and appears to have a total mass of about 1,000 times that of our galaxy. The purple features seen in this image are more than likely caused by particles of matter slamming into one another and heating up as they are dragged back into the black hole.
14 Crab Nebula
A star's stunning death in the constellation Taurus was first observed by Chinese astronomers as the supernova of 1054 A.D. Almost a thousand years later, a marvelous opaque object called a neutron star that was left behind by the explosion has ejected out a cluster of high energy particles into the expanding field known as the Crab Nebula.This combined image seen here has been assembled from three of NASA's Observatories. The Hubble Space Telescope optical images are in red and yellow, the Chandra X-ray image can be seen in blue, and the Spitzer Space Telescope's infrared image is in purple. Like a multitude of other telescopes, Chandra has frequently observed the Crab Nebula since the mission’s inception.
13 Two Spiral Galaxies
This image of the two galaxies seen here was created by three different angles from Hubble. Powerful tidal forces from the larger galaxy, NGC 2207 on the left, have altered the shape of the smaller galaxy, IC 2163, flinging out gas and stars into long streams that expand 100,000 light years. IC 2163 doesn't have enough energy to escape the gravitational pull of NGC 2207, therefore, it is destined to continuously be pulled back, trapped in their shared orbit, and both galaxies will continue to alter and disrupt one another. Eventually, most likely billions of years from now, the two galaxies will mesh into one massive galaxy. It is theorized that a number of present-day galaxies, as well as the Milky Way, were formed from a similar process of amalgamation of smaller galaxies over the course of billions of years.
12 Mars Orbiter
The image above shows, NASA’s MAVEN mission observing the upper atmosphere of Mars in order to assist in understanding climate change on the Red Planet. Early discoveries from the most recent Mars orbiter have started to reveal crucial components about the loss of Mars's atmosphere to space over time. The data collected from NASA's Mars Atmosphere and Volatile Evolution also known as MAVEN mission, included findings of a new process in which solar wind can invade deep into a planetary atmosphere.
11 Inside the Flame Nebula
Taken in infrared light, Chandra X-Ray Observatory compiled this image of an incredible star-forming region, which is known as NGC 2024, also known as the Flame Nebula, located in the constellation of Orion about 1,400 light years from Earth. It's estimated that the stars shown in the center of the cluster are about 200,000 years old, while the ones on the outskirts could be close to 1.5 million years old.
10 Light Echoes
Hubble once again captured another magnificent image, this time of a light echo. Since January of 2002, scientists have been keeping a watchful eye on a rather unusual star called V838 Monocerotis, approximately 20,000 light years from Earth. At the time of the explosion, lasting for a few weeks, it was 600,000 times brighter than our Sun. Eventually the star faded, but the light it discharged traveled outward, illuminating the star's surrounding nebula. The light then hit the gas of the nebula, and bounced off in different directions. Since this occurred, light from that explosion has surged across the universe extinguishing space dust created from what the ESA calls “the most spectacular 'light echo' in the history of astronomy.”
9 Comet Lovejoy
Comet Lovejoy is a long period comet, meaning it can have highly erratic orbits and periods that range anywhere from 200 years to thousands of years, (Lovejoy has an orbital period of approximately 8,000 years). Recently, the comet made its closest pass to Earth, appearing at its brightest. Lovejoy, as seen in this picture, has a detailed ion tail, made of ionized gas energized by ultraviolet light from the Sun that has been pushed outward by solar wind which accounts for the formation of the comet's beautifully structured tail.
8 A Martian Sunrise
Although this image might not appear to be as stunning and eye-popping as some of the others listed here, the photograph above is just one of the numerous astounding pictures captured by the Curiosity rover on Mars. It can be a beautiful and awe-inspiring feeling to witness the sun setting on our own planet, but what could possibly be more captivating than watching a sun set on another world? Maybe one day humans will be able to experience this sight firsthand with our own eyes.
7 Blue Marble
This stunning image dubbed "Blue Marble" is the most detailed authentic color image of Earth. Scientists combined months of observations of Earth's land surface, sea ice, oceans and clouds into an authentic color collage of every square kilometer of our planet. A great deal of the information gathered in this image came from a single remote-sensing-device, NASA’s Moderate Resolution Imaging Spectroradiometer.
6 Curiosity Takes a Selfie
The 1-ton robot made its unprecedented landing on Mars on August 5, 2012. The arrival of Curiosity was extraordinary for so many reasons, including the search for evidence of ancient life on the red planet and its biosphere based on chemotrophic and autotrophic microorganisms, making human settlement on Mars a possibility in the near future. The rover has been doing some pretty cool things ever since it touched down on the red planet. This picture serves as one of those examples: Who would have thought we could send a robot on Mars capable of taking selfies?
5 First Notable Solar Flare of 2015
The sun discharged a mid-level solar flare, on January 12 of 2015 and the striking event was captured by NASA's Solar Dynamics Observatory, which monitors the sun regularly. Solar flares are extremely powerful bursts of radiation. The radiation from the solar flare can't pass through Earth's atmosphere, but when intensified, it can disturb Earth's atmosphere at the layer where GPS communications signals travel.
4 Pillars of Creation
The original photograph of this image was taken by NASA's Hubble Space Telescope on April 1st, 1995 and to celebrate the upcoming 20th anniversary, astronomers compiled a high- resolution photograph of the Pillars of Creation (seen above) which was released to the public in January of this year. The Pillars of Creation are located in the Eagle Nebula, 7,000 light years away, and are made of molecular hydrogen and dust that's being corroded by photoevaporation from the ultraviolet light of nearby hot stars.
3 Europa - Jupiter's Icy Moon
This amazing image is the best recorded view of Jupiter's icy moon. Europa has mystified scientists for quite some time due to the fact that it shows signs of a sub-surface ocean and has significant cracks on its surface. The ocean appears to be protected from damaging radiation, making Europa one of the solar system's ideal chances to host forms of alien life, one of the reason's why it is so enticing to scientists. Europa seems to have all the elements thought to be essential to the origin of life: energy, water and organic chemicals.
2 Saturn Smiles for Cassini
In October of 1997, The Cassini-Huygens probe was launched, eventually arriving at Saturn in 2004. Since then the probe has taken some amazing images, but this Saturn mosaic is beyond spectacular. The image taken shows something that doesn't happen very often. Saturn was backlit by the sun and Cassini was closer than usual, enabling it to capture this stunning false-color shot with remarkable detail of Saturn's rings.
1 Remarkable Solar Eruption
Sol, our sun, is a cascade of extremely-hot plasma intertwined with magnetic fields, and on August 31, 2012, NASA's Solar Dynamics Observatory was watching when the extraordinary magnetic fields on the Sun's surface thrashed outwards with a spiral of plasma during a solar storm. The curve of plasma reached a distance from the surface of 300,000 kilometers, and blasted out at 1,400 kilometers per second.