The Greatest “Amateur” Astronomer of All Time

If you’ve ever seen a beautiful picture of the Universe, thank this pioneer you’ve probably never heard of.

“What you do is, you have your drawing board and a pencil in hand at the telescope. You look in and you make some markings on the paper and you look in again.” -Clyde Tombaugh, discoverer of Pluto

From a clear, dark location on a Moonless night, the Universe’s wonders have been accessible to all mankind for as long as humans have been around: hundreds-of-thousands of years.

Image credit: © P. van de Haar, via

With the exception of a few stars that have appeared to or disappeared from the sensitivity of human eyesight, the occasional nova or supernova, and the slow motions of stars, comets and asteroids through the heavens, the night sky hasn’t changed much over that time. But over the past few hundred years, our understanding of it has, and it began with perhaps the most famous astronomer in history: Galileo.

Image credit: Hulton Archive/Getty Images.

When Galileo pointed his telescope towards the heavens, he opened up the Universe to humanity, no longer limited by the constraints of human anatomy. Even a maximally dilated human pupil, even in a human at the limit of perfect eyesight, was no match for what could be seen through a well-crafted telescope. Details on other worlds, extraterrestrial moons, and hundreds of thousands of stars all hitherto unseen by human eyes before the 17th Century were suddenly available to anyone with this relatively simple tool.

And over time, those tools got more and more powerful.

Image credit: screenshot from Wikipedia, via

The aperture of telescopes, and hence their light-gathering power, increased remarkably as time went on. Astronomers began recording detailed sketches of their observations, cataloguing the positions, brightnesses and descriptions not only of stars, but also of extended, nebulous objects of then-unknown origin or composition.

Image credit: Bill Ferris, Astronomy Sketch of the Day, via

As time went on the combination of:

  • Improved telescope optics and telescope-building techniques,
  • The continuing increase in the size and light-gathering power of these behemoths, and
  • Increasing numbers of observers were able to collaboratively share their observations of the same objects,

the structures of many of these nebulae began to be revealed.

Image credit: Jeremy Perez, via

The first nebulae to be understood were the globular clusters. Initially understood to simply be spherical, nebulous objects with bright cores that faded away as you left their center, improved equipment and observations revealed them to be collections of many stars packed closely together. The only reason they appeared as spherical, nebulous objects to a small, low-power telescope is that they just happened to be very far away.

Image credit: Copperplate engraving published ca. 1860; public domain image.

In the late 1840s, the Leviathan of Parsonstown (above) was completed, a telescope with a 72-inch (1.8 meter) diameter to its main mirror, by far the largest at the time. Through this incredible piece of equipment, a different class of nebula — spiral ones — were revealed to the human eye. The very first objects revealed to have such a structure was Messier 51, the Whirlpool galaxy, sketched (bel0w) by Lord Rosse in 1845.

Image credit: William Parsons, 3rd Earl of Rosse (Lord Rosse), via

But even this combination — the acuity of the human eye augmented by fantastically large and powerful telescopes — was extraordinarily limiting. Even today, observers using astronomical equipment and only their eyes to look through it can scarcely do better than Rosse did nearly two centuries ago.

But the potential was there for so much more. With the relatively new invention of the photograph, it was recognized that if this technique could successfully be applied to astronomy, we would no longer be bound by the limits of the human eye.

Image credit: Smithsonian Institution, National Museum of American History, Archives Center, Draper Family Collection, via Wikimedia Commons user D-bolivar.

Initial attempts at astrophotography in the mid-19th Century ran into all sorts of troubles. For one, the sky appeared to rotate throughout the night (as the Earth beneath was spinning), meaning that a mechanism for canceling out that rotation at a constant rate was needed. The extra weight of a camera could cause a telescope to sag over time, so stabilization was a challenge. Pointing needed to be incredibly accurate (often beyond the precision achievable, even with a telescope) so that objects didn’t shift in the field-of-view over time. And finally, the photographic medium itself had limitations.

Still, some early successes gave indication that this method held some substantial promise.

Image credit: Berkowski (first name unknown), Royal Observatory in Königsberg, Prussia, of the 1851 total solar eclipse.

During a total solar eclipse in 1851, the Sun’s corona was successfully photographed for the first time, and in short order the field of astrophotography was born. Over the next few decades, many developments allowed not only stars but indistinct nebulae to be photographed.

And by the 1880s, for the first time, details invisible to human eyes became visible through astrophotography techniques.

Images credit: Henry Draper, 1880 (left); Andrew Ainslie Common, 1883 (right), both of the Orion Nebula.

But the greatest advancement of that era came not from a professional astronomer like Draper, but from a businessman and engineer whose name you’ve probably never heard of: Isaac Roberts. Roberts took an interest in astrophotography and was pleased with some early results, so he ordered a relatively large (20-inch, or 0.5-meter) reflecting telescope, the largest telescope in England at the time in the 1880s.

And he did what any scientist worth their weight in salt does: he experimented with a variety of techniques, quantified what worked and how well, and incrementally refined his approach.

Image credit: Michael Burton of University of New South Wales, via

He became the first person to perform astrophotography with the photographic plate located at the prime focus of his optical setup, removing the light-loss inherent to the use of a secondary (or tertiary) mirror, achieving some pretty remarkable results.

But his greatest contribution is a legacy that lasts to this day: he developed the technique of piggyback astronomy.

Image credit: Questar piggyback mount from the 1960s, via

If you take an equatorially-mounted telescope — a very stable mount — you can rotate your entire optical setup extremely precisely as the night progresses. The reason you can do this is because the very precise telescope on an equatorial mount is allowing you to align your optics with the rotation of the Earth impeccably.

Early, pre-piggyback telescopes were lucky to get over a minute of exposure time without any noticeable smears or trails; with Roberts’ innovation, that time increased into the hours, allowing for unprecedentedly powerful photographs. The amount of detail you can see is proportional to the square root of the observing time, so observing for 100 times as long means you can see ten times the amount of detail.

And one of the things that came out of his photographs changed astronomy forever.

Image credit: Isaac Roberts (d. 1904), public domain image.

That spiral structure that you see? That’s the Andromeda Galaxy — then known as the Great Nebula in Andromeda — which wasn’t thought to be a spiral at all! This technique, and Roberts’ discovery, literally opened up the Universe to us, and allowed us to discover just what the nature of these nebulae were: galaxies, or island Universes, far beyond our own.

In fact, we can compare how Andromeda looks today with modern astrophotography techniques, and find that there’s practically no discernible difference at all! (With the exception of better detail today.)

Image credit: Christopher Madson, user mads0100 of astrobin, via

It isn’t always the case that the greatest scientists who make the most enduring contributions also happen to be the most beautiful people on the inside, but his epitaph provides a window into a remarkable and kind individual, and a message that we all could aspire to live by.

In memory of Isaac Roberts, Fellow of the Royal Society, one of England’s pioneers in the domain of Celestial Photography. Born at Groes, near Denbigh, 27 January 1829, died at Starfield, Crowboro, Sussex, 17 July 1904, who spent his whole life in the search after Truth, and the endeavour to aid the happiness of others. Heaven is within us.

And these techniques that were developed more than a century ago are still taken advantage of today, opening our eyes to images and details of the Universe that would be invisible to us all otherwise. The next time you see a magnificent image of the cosmos, think of Isaac Roberts, the greatest amateur astronomer of all-time. At least for me, his endeavour to aid the happiness of others shines through with blazing success every time we look at the Universe!

Next Story — The rarest light elements in the Universe
Currently Reading - The rarest light elements in the Universe

Understanding the cosmic origin of all the elements heavier than hydrogen can give us a powerful window into the Universe’s past, as well as insight into our own origins. Image credit: Wikimedia Commons user Cepheus.

The rarest light elements in the Universe

There’s a big gap between Helium and Carbon. Come find out why!

“And argon, krypton, neon, radon, xenon, zinc and rhodium,
And chlorine, cobalt, carbon, copper, tungsten, tin and sodium.
These are the only ones of which the news has come to Harvard,
And there may be many others, but they haven’t been discarvard.”
Tom Lehrer

Immediately after the Big Bang, before the first stars in the Universe ever formed, the Universe consisted of hydrogen (element #1), helium (element #2) and pretty much nothing else. Despite originating from an incredibly hot, dense state, arbitrarily heavy elements weren’t created early on the same way they’re made today in stars. Despite being hot enough to make pretty much anything, the early Universe makes almost nothing for one simple reason: if it was hot-and-dense enough to fuse elements together in the very early stages, it was also hot enough to blast those composite elements apart again.

It’s only when the Universe has cooled enough that elements aren’t immediately split apart — a little more than three minutes in — that we can build our way up the periodic table.

The initial nucleosynthesis reaction chain that produces deuterium, helium-3 and helium-4 in the early Universe. Image credit: Wikimedia Commons user Joanna Kośmider, with modifications by E. Siegel.

But even after just a few minutes, conditions are so low in energy that 99.999999% of the elements cap out at helium. And we don’t make anything new beyond that until we begin to form stars. Although the first stage of stellar burning always involves fusing hydrogen into helium in a star’s core, the stars that are massive enough (more than about 40% as massive as our Sun) will eventually build their way up the periodic table:

  • When the star’s core runs out of hydrogen fuel, it contracts and heats up.
  • When it reaches a temperature of about 100 million K, the helium ignites.
  • With that ignition, helium burning commences, where three helium atoms fuse together to create carbon (element #6), releasing energy in the process.
A new star cluster full of bright, giant stars that will produce copious amounts of carbon (and more) in their cores. Image credit: ESO / G. Beccari, via

This is the process at play in red giant stars, with more massive stars creating elements such as nitrogen, oxygen, neon, magnesium, silicon, sulphur and iron-cobalt-and-nickel. In addition, stellar burning also produces free neutrons, which can combine with the pre-existing elements to climb up the periodic table one element at a time, all the way up to elements like lead and bismuth (elements #82 and #83). And finally, the absolute most massive stars will die in a spectacular supernova explosion, leading to a runaway fusion reaction that — in principle — should produce everything that’s known in the periodic table and beyond, creating every element possible.

The nebula from supernova remnant W49B, still visible in X-rays, radio and infrared wavelengths. Image credit: X-ray: NASA/CXC/MIT/L.Lopez et al.; Infrared: Palomar; Radio: NSF/NRAO/VLA.

Every element possible, that is, except the three we skipped. You see, the Universe starts off with hydrogen and helium, all stars produce helium, and then stars over a certain mass threshold produce carbon, nitrogen, oxygen and lots of heavier elements. But carbon was already element #6; what about lithium, beryllium and boron (elements #3, #4 and #5)? When we look out at the Universe and the Solar System, and ask what the abundances of the elements are, we notice there’s a tremendous gap between helium and carbon, like those three elements are incredibly suppressed.

Image credit: Wikimedia Commons user MHz`as, with data from Katharina Lodders (2003). The Astrophysical Journal 591: 1220–1247.

You can’t make those elements by fusing lighter ones together, since adding hydrogen to helium would create lithium-5, which is unstable, and adding two heliums together would create beryllium-8, which is unstable. (In fact, all nuclei with a mass of 5 or 8 are unstable.) You can’t make them from stellar reactions involving elements like carbon or above, since those only create heavier elements, not lighter ones. In fact, you can’t make the first of the heavier-than-helium elements in stars at all.

A model of a plant cell, with primary and secondary cell walls. Without boron, plant cell walls wouldn’t exist. Image credit: Caroline Dahl, under a c.c.a.-s.a.-3.0 license.

And yet, lithium, beryllium and boron not only exist, but boron in particular is vital for life-as-we-know-it on Earth. Without boron, there would be no such thing as a cell wall, and hence, no such thing as a plant. (For some of us the lithium batteries in our cellphones may be equally as indispensable!)

Yet plants exist, lithium, beryllium and boron exist, and so somehow, these elements must have been created. The keys, believe it or not, are the most energetic sources of particles in the Universe: black holes, neutron stars, supernovae and active galaxies. When these cosmic catastrophes ignite, become active or even explode, they don’t just emit particles. They emit the highest energy particles in the known Universe.

Image credit: NASA / JPL-Caltech; Chandra / Spitzer / Hubble composite of the Cassiopeia A supernova remnant.

And when those energetic particles (known as cosmic rays) strike a heavier element — one created in a star — it can blast it apart, creating a cascade of lower-mass particles. This process, known as spallation, is how the lithium, beryllium and boron found on Earth was formed, and the only reason why these elements can be found at all on our planet. These three elements are by far the rarest of all the light elements, and this process is the only reason they’re around at all. The next time you see a plant, think not only of the evolutionary story that allowed it to be so, but the cosmic one, that enabled the elements essential to it to even exist. Without the most catastrophic, energetic events in the Universe, three of the lightest elements, lithium, beryllium and boron, simply would not be.

This post first appeared at Forbes, and is brought to you ad-free by our Patreon supporters. Comment on our forum, & buy our first book: Beyond The Galaxy!

Next Story — Science: where finding nothing is the biggest victory of all
Currently Reading - Science: where finding nothing is the biggest victory of all

A Higgs boson decaying into Fermions — taus and bottom quarks — in 2012 at the CMS detector. The Higgs boson is the last new particle discovery, and it completes the Standard Model. Image credit: CERN / CMS collaboration.

Science: where finding nothing is the biggest victory of all

“Eureka!” is not always as powerful as “that’s what I thought!”

“Reality is what kicks back when you kick it. This is just what physicists do with their particle accelerators. We kick reality and feel it kick back. From the intensity and duration of thousands of those kicks over many years, we have formed a coherent theory of matter and forces, called the standard model, that currently agrees with all observations.” -Victor J. Stenger

Reading the science news over the past month, you might conclude that it’s been one defeat after another for physics. After all:

Yet these apparent defeats are merely a thin veil covering the greatest truth of all: physics really is incredibly well-understood.

Image credit: E. Siegel, of the known particles in the Standard Model. This is still everything that’s been directly discovered.

From a particle physics perspective, the Standard Model describes all the normal matter we’ve ever observed or detected directly. Combined with General Relativity, our leading theory of gravitation, the four fundamental forces describing all the particles and their interactions — the strong nuclear, electromagnetic, weak nuclear and gravitational forces — are almost completely understood. To be honest, they’re so well understood that most people take this for granted.

The fabric of spacetime, illustrated, with ripples and deformations due to mass. Image credit: European Gravitational Observatory, Lionel BRET/EUROLIOS.

General Relativity was formulated in the 1910s; the Standard Model’s predictions were finalized in the 1960s. For the past 50 years, the greatest novel ideas in theoretical physics, from grand unification to neutrinoless double beta decay to extra dimensions to supersymmetry, have all failed to turn up a direct experimental signature of a new particle or interaction beyond the known forces. We’ve reached the point where the only the most esoteric questions respecting the matter we know, questions concerning the gravitational field of an electron passing through a double slit or the information from the particles falling into a black hole, for example, aren’t answered by our current theories.

We don’t know what happens at the singularity inside a black hole, either, but we’re a long way from gathering experimental data about that! Image credit: NASA, via

If you put any Standard Model particle or set of particles out into the Universe and subject it to any sort of conditions at any energies, if you allow it to collide in a controlled or uncontrolled fashion with low energy, high energy or ultra-high energy particles, you can describe every single interaction by these simple sets of laws. If you shield these particles from everything you can conceive of in the Universe, you see exactly what these laws predict.

The key thing — the greatest victory — is that we don’t see anything elseat all.

The observed Higgs decay channels vs. the Standard Model agreement, with the latest data from ATLAS and CMS included. The agreement is astounding. Images credit: André David, via Twitter at

We don’t see any unexpected or unanticipated decays. We don’t see any collisions whose properties we can’t explain. We don’t see the violation of laws or symmetries we don’t expect. We don’t see even tiny amounts of a signal that’s forbidden by the Standard Model or General Relativity. We don’t see proton decay; we don’t see flavor-changing-neutral-currents; we don’t see CPT violation; we don’t see anything move faster than the speed of light in a vacuum. And when it comes to the new things that we do see, they’re exactly in line with what’s predicted, from gravitational frame-dragging to the Higgs boson decaying exactly as we expect to pulsars spinning in perfect time to gravitational radiation matching up perfectly with what Einstein predicted 101 years prior.

The inspiral and merger gravitational wave signal extracted from the event on December 26, 2015. Image credit: Figure 1 from B. P. Abbott et al. (LIGO Scientific Collaboration and Virgo Collaboration), Phys. Rev. Lett. 116, 241103 — Published 15 June 2016.

There are lots of stories out there about how physics is broken, and how we need a massive new breakthrough or a paradigm shift to keep the enterprise of new discoveries going. What nonsense! The truth is that the laws of physics we have in place are the most successful sets of laws we’ve ever come up with. They’ve been tested more robustly than any other set of laws ever, and they’ve passed every single one. We might not understand why the laws are the way they are, or why the Universe comes with certain properties that the Standard Model and General Relativity don’t have an explanation for, such as:

  • dark matter,
  • dark energy,
  • the tiny, non-zero masses of neutrinos,
  • or the matter/antimatter asymmetry of the Universe.

There’s more to learn, for certain. There are more questions out there to be answered. What these null results — these non-discoveries — are telling us is something phenomenal and profound: that physics isn’t over and done, but rather that the hints of what comes next requires looking far, far deeper than we’re presently looking. That means higher energies, larger telescopes, more particle collisions, more sensitive detectors, more significant digits closer to the speed of light or absolute zero and quite likely better, newer ideas than the ones we’ve been pursuing fruitlessly for so long.

The farthest galaxy ever spectroscopically confirmed. To push the frontiers even farther, we’ll need to go even deeper into the Universe. Image credits: NASA, ESA, and A. Feild (STScI).

It’s a great opportunity for creative scientists and a wonderful time to be alive. We can honestly look back and marvel at how far we’ve come, what we’ve already discovered, and how miraculously well it all works. At the same time, we can look ahead at the great mysteries in front of us, and contemplate just what marvelous secrets about nature they might hold when we finally unlock them. In the meantime, it’s no nightmare that these answers remain hidden; it’s merely the latest, greatest challenge that the Universe has presented us with. The fact that we’ve found nothing new that’s compelling so far means our journey must continue. The promised land is still ahead.

This post first appeared at Forbes, and is brought to you ad-free by our Patreon supporters. Comment on our forum, & buy our first book: Beyond The Galaxy!

Next Story — How did the Universe get its first supermassive black holes?
Currently Reading - How did the Universe get its first supermassive black holes?

Illustration of the distant galaxy CR7, which last year was discovered to house a pristine population of stars formed from the material direct from the Big Bang. Image credit: M. Kornmesser / ESO.

How did the Universe get its first supermassive black holes?

How they get so big so fast is a mystery. Could “direct collapse” be the solution we’re seeking?

“For something to collapse, not all systems have to shut down. In most cases, just one system is enough.” -Robert Kiyosaki

At the center of almost every large galaxy lies a supermassive black hole, millions or even billions of times the mass of our Sun in scale. Our Universe has been around for 13.8 billion years, which you might think is plenty of time to form a black hole that large. Yet the farther and farther back in time we look, every supermassive black hole we measure seems to have roughly the same mass as the ones today. In other words, while the largest-scale structures in the Universe:

  • giant elliptical galaxies,
  • ultra-massive clusters with thousands of times the mass of the Milky Way,
  • and galactic filaments that are hundreds of millions of light years across,

took billions of years to form, there are ultra-massive black holes that have been around as far back as we can see.

An illustrated timeline of the Universe’s history. Image credit: European Southern Observatory (ESO).

They don’t predate stars, but they are found in the earliest massive galaxies we know how to measure. The crazy explanation is that the Universe was born with these cosmic behemoths, but that flies in the face of everything else we know about structure formation, including the magnitudes and mass/size scales of the fluctuations that gave rise to everything we see today. The new physics that would have to be hypothesized to create a Universe that was born with extremely large black holes is not only preposterous, it’s incredibly constrained by observations of the cosmic background light populating the cosmos.

The fluctuations in the Cosmic Microwave Background, as seen by Planck. Image credit: ESA and the Planck collaboration.

But there are two “mundane” explanations, or explanations that don’t involve any new fundamental physics beyond that which we currently know.

  1. A huge set of starbursts — a giant rush of catastrophic star-formation — triggered the formation of a great many stellar-mass black holes in just a few million years. Over time, they merged together and migrated towards the center of the galaxy, giving rise to a supermassive black hole in very short order.
  2. A supermassive black hole formed by direct collapse of matter into a very large, massive black hole all at once, providing the seed for ultramassive black holes to grow over a relatively short timescale.

The first scenario, by a great many people, is thought to be the simplest explanation, since we see plenty of evidence of how this could work, even today.

The starburst galaxy Henize 2–10, located 30 million light years away. Image credit: X-ray (NASA/CXC/Virginia/A.Reines et al); Radio (NRAO/AUI/NSF); Optical (NASA/STScI).

Star formation is known to occur in bursts, with the greatest rates of star formation occurring in the first three billion years of the Universe, and falling ever since. When stars form en masse, they produce stars of all different masses and colors, including copious numbers of stars over 20, 50, 100 or even 200 solar masses. These massive, blue, hot stars are both the brightest and the shortest lived, and they end their lives in core-collapse supernovae, almost all of which give rise to black holes. Because of the dynamics of gravity, the way these most massive objects work is that they interact with the other stars around them, kick them around while sinking to the center of a cluster-or-galaxy, and then merge together. It’s a simple, conservative scenario. But it might also be insufficient.

Last year, the galaxy CR7 was discovered: a strong candidate for having a truly pristine population of stars. Pristine means that this would be the very first time stars were forming inside this galaxy since the Big Bang, and the science supports this view quite strongly. Yet if we look at even this galaxy, we find something spectacular about it: it also exhibits evidence for a supermassive black hole. And while the starburst explanation is tempting, it may not line up completely with what we see. In a paper written earlier this year, scientists Aaron Smith, Volker Bromm and Abraham Loeb came up with a different explanation: perhaps they were seeing the first evidence for a direct-collapse black hole!

The X-ray and optical images of a small galaxy containing a black hole many tens of thousands of times the mass of our Sun. These black holes may have arisen first in the Universe by the direct collapse of matter. Image credit: X-ray: NASA/CXC/Univ of Michigan/V.F.Baldassare, et al; Optical: SDSS; Illustration: NASA/CXC/M.Weiss.

This galaxy, sending light from 13 billion years ago, has to see that light travel throughout the expanding Universe, where its wavelengths get stretched from ultraviolet through the visible portion of the spectrum and all the way into the infrared. Still, the hottest, bluest stars — which it’s rich in — cause intense ultraviolet emission from the atoms present: hydrogen and helium. These emission lines originate from slightly different parts of the galaxy, and thanks to the incredible technology of the 2015 observations detecting them, we were able to determine that the hydrogen emissions appear to be moving quickly, at 160 km/s, relative to the helium emissions. When Smith, Bromm and Loeb try to model these emissions using simulations, they find that a massive source of radiation must be present at the center, creating an ionized bubble and driving an expanding shell of gas out from the center.

A rich nebula of gas, pushed out into the interstellar medium by the hot, new stars formed in the central region. Image credit: Gemini Observatory / AURA.

There are two explanations to consider: either there’s a massive star cluster at an incredibly high temperature of 100,000 K, or there’s a massive black hole driving it. The big difference between the two models is that the massive black hole produces the offset speed between the hydrogen and helium as well as the incredible size of the region (over 50,000 light years!) while the primordial massive star cluster does not.

These are simulations only, however; if you want to confirm your picture, you need evidence to decide one way or the other. The way we’ll be able to determine whether there truly is a massive black hole will be observational, and it will involve looking for the characteristic radio emissions from black holes.

A small section of the Karl Jansky Very Large Array, one of the world’s largest and most powerful arrays of radio telescopes. Image credit: John Fowler, under a cc-by-2.0 license.

The largest, most advanced radio telescope arrays in the world are on the verge of being up to the task! The evidence pointing to the existence of direct-collapse black holes is tantalizing and suggestive, but we’re not over the threshold yet. In order to get there, we need to see the proof. But the theoretical possibility has been raised, and the gauntlet has been thrown down. It’s time to collect the evidence and let nature decide!

This post first appeared at Forbes, and is brought to you ad-free by our Patreon supporters. Comment on our forum, & buy our first book: Beyond The Galaxy!

Next Story — Cassini prepares for its final, suicidal mission
Currently Reading - Cassini prepares for its final, suicidal mission

A natural color view of Saturn, its rings edge-on and its largest moon, Titan, as viewed from the Cassini spacecraft. Image credit: NASA/JPL/Space Science Institute.

Cassini prepares for its final, suicidal mission

After nearly 20 years in orbit around Saturn, Cassini prepares to say goodbye.

“All the atoms of our bodies will be blown into space in the disintegration of the solar system, to live on forever as mass or energy.” -Carolyn Porco

In 1997, NASA’s Cassini spacecraft was launched for a journey to Saturn, where it would study our Solar System’s ringed world as never before.

Visible and radio images of Saturn’s rings and their structure, as delivered by Cassini. Image credit: NASA/JPL/Space Science Institute.

It delivered beyond our wildest expectations, presenting breathtaking new views of the least dense planet known.

Saturn in eclipse, perhaps the most stunning image of the planet ever taken. Image credit: NASA/JPL/Space Science Institute.

It viewed Saturn in eclipse, discovering two new, outer rings in the process.

An infrared view of Saturn, along with its ring’s shadows on the planet’s atmosphere. Image credit: NASA / JPL / Space Science Institute.

Its infrared eyes viewed Saturn’s hazes beneath the top-level clouds.

A false-color image highlighting Saturn’s hurricane over its north pole, inside the much larger hexagon-shaped feature. Image credit: NASA/JPL-Caltech/SSI.

The north pole of Saturn was found to possess a strange hexagonal storm, thought to be stable over century-long timescales.

Descent Imager/Spectral Radiometer (DISR) image of Titan taken at 2km altitude during the descent. Image credit: ESA/NASA/JPL/University of Arizona.

The Huygens probe released by it descended onto Titan, its largest moon, discovering an incredible landscape, liquid methane lakes and even waterfalls.

Iapetus, the second Saturn moon ever discovered, as imaged by Cassini. Image credit: NASA / JPL-Caltech / Space Science Institute / Cassini.

The mystery of Iapetus, its two-toned moon, was solved as well: dark material from the captured comet, Phoebe, causes the ice on one side to sublimate and settle on the other.

The captured Kuiper Belt object, Phoebe, now one of Saturn’s moons. Image credit: NASA/JPL/Space Science Institute.

Enceladus, an icy, outer moon, was found to contain a subsurface water-ice ocean, which erupts in spectacular geysers.

This is a false-color image of jets (blue areas) in the southern hemisphere of Enceladus taken with the Cassini spacecraft narrow-angle camera on Nov. 27, 2005. Image credit: NASA/JPL/Space Science Institute.

The rings were determined to be made up of 99.9% water-ice, and are at least hundreds of millions of years old.

One of Saturn’s small moons passing in its orbit through a gap in the rings. Image credit: NASA/JPL/Space Science Institute.

And finally, it discovered and viewed the largest storm in the Solar System’s known history: 2011′s Saturnian hurricane.

Image credit: NASA / JPL-Caltech / Space Science Institute, of the great storm’s evolution over a period of 8 months.

Mostly Mute Monday tells the story of a single astronomical phenomenon or object in visuals, images and video in no more than 200 words. Cassini will end its mission in 2017 by crashing into Saturn, thereby avoiding any possible contamination of moons with organics on them.

This post first appeared at Forbes, and is brought to you ad-free by our Patreon supporters. Comment on our forum, & buy our first book: Beyond The Galaxy!

Sign up to continue reading what matters most to you

Great stories deserve a great audience

Continue reading