The 10 Best Hubble Telescope Images and What They Revealed 

Decades of Discoveries

The ongoing Hubble mission to photograph the natural artistry of the universe has undoubtedly succeeded in revealing the vast wonders of space and the myriad treasures that await humankind's journey into its depths.

The Hubble Space Telescope was launched in 1990 aboard the Space Shuttle Discovery. It is 13.2 meters long, 4.2 meters wide (with a 2.4 meter mirror), and it weighs 12.2 tonnes. It has been observing cosmic structures with its onboard cameras for several decades now.

The Hubble Telescope's discoveries have surpassed our expectations and facilitated a greater understanding of the universe. We now have a more precise age for the universe—13.787 billion years—and we know it is expanding at an accelerating rate.

Hubble has also found that black holes reside at the center of most galaxies, that extrasolar planets exist around many stars, and that stellar nurseries and protoplanetary disks provide the building blocks for star systems such as our own.

From neutron stars to supernova explosions, Hubble has been our window into the cosmos. Courtesy of NASA and the ESA, this article will showcase the 10 best Hubble Telescope pictures. As with every list of favorites, this is a personal assessment, but one that I hope you will enjoy.

1. Spiral Planetary Nebula, NGC 5189

This planetary nebula bears a striking resemblance to the number two. Planetary nebulae form when medium-sized stars like the Sun reach the end of their lives and expel their outer layers into space. That material is heated by the exposed stellar core, producing the glowing, nebulous clouds we see. They are usually more spherical, and they don't contain any actual "planets."

The stellar core of NGC 5189 is a rare low-mass Wolf-Rayet star, a transitional object that will eventually become a super-dense white dwarf. It is orbited by another white dwarf that completes a circuit every four days. The nebula's unusual shape is thought to result from the binary system's precessing symmetry axis, which directs successive outflows of material along shifting paths. A 2017 study has even suggested that a third star may be involved, making the system a triple.

2. Helix Nebula, NGC 7293

Sometimes called the "Eye of God," the Helix Nebula is only 650 light years from the Earth and is about 2.5 light years wide. To capture this large-scale image of the nebula, the Hubble Telescope was used in conjunction with the Cerro Tololo Inter-American Observatory in Chile.

The Helix Nebula is a planetary nebula that is expanding at a rate of 31 km per second, with an age of about 10,000 years. The stellar core is a particularly hot white dwarf—about 110,000°C—giving the surrounding gases their bright glow. A second disk, nearly perpendicular to the first, has been identified in 3D models of the nebula; it may have been shaped by a companion star. 

3. Crab Nebula, NGC 1952

When a large star runs out of fuel and its core collapses under gravity, there is a more violent expulsion of its outer layers called a supernova explosion. The Crab Nebula is what this looks like—a supernova remnant expanding at a rate of 1,500 km per second.

The stellar core was too big to become a white dwarf. It collapsed into an even denser neutron star, just 20 km across, called the Crab Pulsar, which is a strong emitter of X-rays and gamma rays.

The supernova event was first recorded by Chinese astronomers in 1054 who noticed a brilliant new star in the constellation Taurus. John Bevis discovered the resultant nebula through his telescope in 1731. It exists within our Milky Way galaxy at a distance of 6,500 light years from Earth. 

4. Orion Nebula, NGC 1976

The Orion Nebula is 1,344 light years from Earth and 24 light years wide. It appears slightly south of Orion's Belt and is visible to the naked eye. The nebula is a stellar nursery with about 700 stars in the process of forming. Upwards of 150 protoplanetary disks have been observed by Hubble, revealing the regularity with which planets are formed around stars in the universe.

The Orion Nebula is known for its beautiful spectrum of colours. The red coloration is caused by heated hydrogen gas, and the violet is from nitrogen heated by radiation from large O-type stars within deeper regions of the nebula. The slight green coloration is caused by heated oxygen gas interacting in a way that can only occur in the deep vacuum of space. 

5. Tarantula Nebula, NGC 2070

At a width of 1000 light years, the Tarantula Nebula is one of the largest star-forming region in our local region of space. Also called "30 Doradus," it resides within a neighboring galaxy called the Large Magellanic Cloud at a distance of 160,000 light years from Earth. It is so luminous that if it were as close as the Orion Nebula, it would be clearly visible in the daytime sky. 

The large glowing fibers that meander through the nebula resemble spider's legs, giving the structure its name. These wispy clouds are produced by the radiative pressure of massive stars that have formed within the nebula, which "blow" the hydrogen gas in all directions, carving out pockets of space around themselves. These cavities allow Hubble to resolve the individual stars embedded within them. 

6. Colliding Galaxies, NGC 2207 and IC 2163

These colliding spiral galaxies were discovered at different times: NGC 2207 by John Herschel in 1835, and IC 2163 in 1898. The Hubble Telescope released this picture of them in 1999. They are presently two separate galaxies, but in a billion years they will become a single elliptical or disk-shaped galaxy. The larger galaxy (NGC 2207) is tidally stripping stars and material from the smaller galaxy. They are 114 million light years from Earth. 

7. The Rose: Arp 273 (UGC 1810 and UGC 1813)

Collectively known as Arp 273, the larger of these two galaxies is UGC 1810 and the smaller is UGC 1813. Together they resemble an enormous cosmic rose, sitting in space, 300 million light years from Earth.

It is theorized that the smaller galaxy passed through the larger one, and the resulting gravitational tides have distorted the larger galaxy's disk into the rose-like shape we see. This interaction may also explain why the larger galaxy's outermost spiral arm appears stretched into a wide ring—a signature of a galaxy passing through another.

8. Hubble Extreme Deep Field

NASA and ESA released this picture in September 2012. It might not look like much, but each of those points of light is an entire galaxy containing billions of stars. You can even see the spiral arms on some of them. There are about 5,500 galaxies in the image with the faintest being one ten billionth of what the human eye is capable of visualizing.

To capture this image, Hubble revisited the same patch of sky in the constellation Fornax, accumulating 23 days of total exposure time over 10 years. Light from the farthest galaxies had been travelling for 13.2 billion years before reaching the telescope, making the XDF a window into the earliest billion years of the universe's existence. 

9. Carina Nebula, or "Mystic Mountain," NGC 3372

The Carina Nebula is 7,500 light years from Earth and about ten times larger than the better known Orion Nebula. The portion of the nebula displayed in this image is called Mystic Mountain because of its extraordinary pillars of gas. It is a region of intense star birth, with several large O-type stars already formed (the hottest and brightest kind).

Mystic Mountain is a pillar of cold gas and dust, three light-years tall, being gradually eroded by the intense radiation from nearby bright stars. The pillar is also being shaped from within, as infant stars fire jets of gas that stream from its peaks.

10. Whirlpool Galaxy, NGC 5194

Although well-known, this image of the Whirlpool galaxy may be the most spectacular panorama of natural beauty ever observed. The NGC 5194 spiral galaxy is about 23 million light years from Earth and about 60,000 light years across. Seen here with its smaller companion (NGC 5195), it can be easily seen with Earth-based telescopes, and it was discovered in 1773 by Charles Messier.

The Whirlpool galaxy's spiral structure is thought to be caused by a gravitational interaction with NGC 5195, which likely passed through its disk around 500 million years ago. The spiral structure produces dense regions of hydrogen gas, leading to a high rate of star formation and, thus, the glow of its spiral arms. The whirlpool galaxy hosts a supermassive black hole at its core.

Wondrous Cosmic Behemoths

The narratives of exploding stars and tumbling galaxies provided by astrophysicists from around the world add to the majestic natural beauty revealed by Hubble. I hope you enjoyed learning about these wonders of the universe as much as I did. The selections were, of course, a matter of opinion. I invite you to explore the Hubble Telescope's online gallery to find hundreds more.