The Cosmos in a Heartbeat 1: A Love Affair with the Cosmos

by Shane L. Larson

The night sky over the Pando Forest in central Utah. Pando is an 80,000 year old aspen grove — it has seen almost 30 million nights like this one, far more than any single human will ever live through. [Image: Shane L. Larson]

The Cosmos is vast in ways that are difficult for humans to wrap their brains around. That doesn’t stop us from talking about it, of course, but it is vast, none-the-less. What do I mean by “vast?”

The Universe is 13.8 BILLION years old, 100 million times older than the oldest human. When you and I go out at night there are almost 10,000 individual stars we can see with the naked eye, but the Milky Way has some 400 BILLION individual stars, and there are some 500 BILLION individual galaxies in all the Cosmos. If you and I could somehow take a road trip, from one side of the Milky Way to the other, travelling at the fastest speed possible (the speed of light) it would take us 100,000 years to go from one side to the other —1000 times longer than any human has ever lived. And the entire Cosmos itself is far vaster.

These sorts of factoids are fun to know and think about. They melt your brain, and they can impress your friends and family at a dinner party. But what is always remarkable to me is even though you and I occupy only one small part of the Cosmos in space and time, we have still managed to piece together a story about the history of the Universe — its overall size and content, when it was born, how it has lived its long life to date, and what its ultimate future might be.  As a species, we have only been cognizant of the science we call astronomy for a few centuries, though we have been looking outward into the Cosmos for far longer. But in those few centuries, in just a handful of human lifetimes, we have managed to piece the story together. Even though a human only lives through the merest flash of a moment in Cosmic time, less than a single heartbeat in the life of the Cosmos.  This is a story about how we learn what we learn about the Universe around us and our place within it.

Me in elementary school. I’m not sure what I’m doing in this picture, but I’m pretty sure I’m not getting into trouble [Image: Pat Larson]

I am a professional astronomer, but like most of us, my love-affair with the Cosmos began when I was young. I would spend long hours out in the backyard, laying on the ground trying to learn my constellations with an old beat-up paper star wheel. We didn’t have a telescope (they were expensive), but my mom is an avid birder and she had an old spotting scope. She used to let me take it out in the backyard and put it on an old card table, and I discovered there was far more to the Cosmos than my naked eye could see. I looked at the Moon and discovered craters, and mountains and sinuous canyons. I looked at the brightest points of light I could see, and found out they were Mars, and Jupiter, and Saturn — other worlds, tantalizingly close, but so very far away. There were other things to discover as well.

My Mom’s spotting scope (she still has it!). This is the first telescope I ever looked at the sky with.

In the corner of the sky we call Andromeda, there is a smudge of light that looks like a wisp of cloud. It is the most distant object you can see with your naked eye, and we call it the Andromeda Galaxy. It is 2.1 million light years away, which means if you step outside tonight and look at the Andromeda Galaxy, the light that falls in your eye and makes its impression on your mind is ancient light. It left the Andromeda Galaxy 2 million years ago, at a time when the most advanced hominids on Earth were Australopithecus, and the world was dominated by mega-fauna like sabre-toothed cats (smilodons) and mastodons. This is one of the fundamental truths in astronomy: looking out is looking back in time, and the farther we can look, the more about the long history of the Cosmos we can discern. As astronomers we are always on an epic quest to build better tools to help us probe farther out into the Cosmos. 

My first astronomical telescope, an 8-inch reflector I built called Albireo, based on Richard Berry’s excellent book “Build your own telescope” .[Image: Shane L. Larson]

Let’s look back to the time when I decided to become a professional astronomer, sometime during my early years in college. Thirty years ago, in 1988, I was already improving my backyard astronomy. I’d left my mom’s spotting scope at home, and after not too long had built my own telescope. It was bigger than my mom’s spotting scope, and could see much more of the Universe. At the same time, the largest telescope used by professional astronomers was the 5-meter (200-inch) Hale Telescope on Mount Palomar. At that time, it was the largest telescope in the world, a title it had held for 40 years since it was built in 1948. Astronomers are still using it today.

The 5-meter Hale Telescope on Mount Palomar was the largest telescope in the world for 40+ years. This image was taken in the dome on a night in 2009 when one of our observing runs was clouded out. Astronomers still use this telescope today. [Image: Shane L. Larson]

So what do astronomers do with these great machines? On any given night, whether you are looking through a backyard telescope, or looking through a telescope like the Hale, the sky looks much like it did the night before. The stars are still where you remember them, living out their lives slowly, changing little. We find new and interesting things, of course, but what we are often most interested in are the unexpected events — energetic and dramatic events that appear in the sky and then are gone. Astronomers call such things “transients.” Consider a “supernova.” One of the things we have learned over the past century is that stars, like people, are born, they live long lives, and they ultimately perish. When the most massive stars reach the ends of their lives, they die in a titanic explosion that, for a few brief days or weeks, sheds enough light to be visible in the night sky. The last time an explosion like this was seen in the Milky Way was in 1604, before the first telescope was ever used to study the sky!  Four hundred years ago, we didn’t know what supernovae were, but the events were momentous enough to note down.

An astrolabe from the Adler Planetarium collection, showing the Supernova of 1604. [Image: Adler Planetarium, notations from Pedro Raposo]

You can find written notations of the 1604 supernova in paper star atlases of the day, but one of my favorites is shown in the astrolabe above, which is part of the Adler Planetarium’s historical collection. An astrolabe is a mechanical device used to visually measure the positions of stars in the sky by eye. They are elaborate and intricate machines, but also stunning and artistic in their elegance and form.You’ll see on the upper right ring of this astrolabe that Supernova 1604 is marked, preserved forever in the solid copper record of the day. You’ll notice there are other transients on this astrolabe, including the previous supernova observed in the Milky Way (Supernova 1572), as well as the great comet of 1618.  My colleague Pedro Raposo, an astronomy historian at the Adler Planetarium, points out that depicting supernova and comets on an astrolabe is an indicator of how our understanding of the Universe was evolving. At that time, we didn’t know what supernovae and comets were. Their nature was widely debated, with many believing they were atmospheric phenomena. The fact that they were recorded on a mechanical starmap is an indicator that we were slowly coming to the understanding that these events were in the deep, cosmic sky. Our views about the Cosmos were changing.

Supernova 1987a, imaged by the Hubble Space Telescope in 1995, eight years after the explosion. [Image: STScI/NASA/ESA]

Now spool ahead to the 1980s. In 1988 we understood much more about supernovae than we did when that astrolabe was built, but we had never been given the opportunity to study one up close. In the entire 400 year history of telescopic astronomy, there has not been a supernova here in our own galaxy, close enough for us to see all the fine details and study how stars reach the end of their lives. But on 23 February 1987, there was a supernova not too far away, in a small galaxy next door to the Milky Way, called the Large Magellanic Cloud. We called it Supernova 1987A, and it was visible to the eye for several months. Astronomers could see it in their telescopes, and still today the most powerful telescopes can detect the faint echoes of light coming from the explosion.

But SN1987A was special for another reason. When a star dies in a supernova, it not only sheds light, it also releases a cosmic rain of particles called neutrinos. When this supernova exploded, 10⁵⁷ neutrinos were released (that’s 100,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 neutrinos!), bursting out in every direction in the Universe. Neutrinos are notoriously hard to detect because they tend to go blasting right through matter as if it isn’t even there. When the neutrino burst from SN 1987A reached Earth, 30 trillion of them went through me and you and every other person on planet Earth, and we didn’t even know it! But astronomers had been thinking about this for a long time, and had constructed a special observatory — a neutrino telescope.

The Kamioka Observatory “KamiokaNDE” experiment, one of the neutrino observatories that captured a few of the neutrinos from SN1987a. [Image: ICRR/University of Tokyo]

A neutrino telescope is not like an ordinary telescope, because neutrinos are very difficult to capture. Instead neutrino telescopes watch for neutrinos interacting with other things. In 1987, the worlds largest neutrino telescopes were enormous tanks of very pure water underground. Sometimes when a neutrino goes through these tanks, their interaction with the atoms in the water generates bursts of light that can be detected with very sensitive cameras lining the inside walls of the tank. In the hours right before telescopes detected the light from the supernova, 25 neutrinos were seen in detectors around the world. Only 25 neutrinos from all the 10⁵⁷ that were released in the supernova, but it was enough to convince astronomers they had seen neutrinos from the supernova. This was the first time in history that astronomers had detected an astrophysical event with light AND particles; this was the beginning of what we now call “multi-messenger astronomy.” It was a watershed moment in our quest to probe the Cosmos — we had, for the first time, used two machines to probe the Cosmos using different pieces of information together to make one story. It was the beginning of a new way of thinking and learning about the Universe, and it is a story that is still going on today.

This was the frontier of astronomy 30 years ago. In our next post, we’ll fast-forward to today and ponder how we plumb the deep sky with all our modern technology and combine it with the meager knowledge that we’ve gained over the past few decades.

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This post is the first of three based on a talk I have given many times over the last few years, updating it each time to reflect the latest coolest things. The complete set posts of the series are:

The Cosmos in a Heartbeat 1: A Love Affair with the Cosmos (this post)

The Cosmos in a Heartbeat 2: Coming of Age

The Cosmos in a Heartbeat 3: The End is Just the Beginning

This post was enabled by a new version of the talk done as a Kavli Fulldome Lecture at the Adler Planetarium in Chicago. The talk was captured in full 360, and you can watch it on YouTube here. If you have GoogleCardboard, click on the Cardboard Icon when the movie starts playing; if you watch it on your phone, moving your phone around will let you look at the entire dome!

I would like to thank all my colleagues at Adler who worked so hard to translate what was in my brain into a story told in the immersive cradle of the Grangier Sky Theater. The talk was given on 9 Nov and 10 Nov 2018.

I also put this post up today to celebrate the occasion of Carl Sagan’s birthday. I, like many around me, was inspired at the right moment by exposure to Sagan’s “Cosmos: A Personal Voyage”. Friday (9 Nov 2018) would have been Carl’s 84th birthday. He left us more than 20  years ago now, but I still hear his voice when I think about and ponder the deep mysteries of the Cosmos around us. Happy birthday, Carl.

First Light

by Shane L. Larson

In the fall of this year, I turned 43 years old.  Four days after my birthday I participated in a long standing tradition that has been handed down through many generations.  It began 403 years ago, on a cool autumn evening in Padua, Italy. Galileo Galilei, then 45 years old, had crafted a simple telescope after hearing of the “spyglass” invented by the Dutch.  Galileo was the first person to turn his telescope toward the sky, letting starlight flit through the shaped lenses and, for the first time, fall on human eyes.  First light.  Galileo beheld a Cosmos full of unexpected wonders, startling revelations, and new mysteries.  Sweeping the faint glow of the Milky Way, easily visible in those bygone days before urban lighting, he discovered it was comprised of innumerable stars — more than he could sketch!  He could see roughness and surface detail on the Moon, which up to that time had been thought to be perfectly smooth. Much to his surprise, he discovered that Venus had phases, like the Moon. And perhaps most importantly, he saw bright points of lights orbiting Jupiter — Galileo was the first person to discover other worlds in the Cosmos.

One of Galileo’s early telescopes.

Today, the heavens are more well known than they were 400 years ago, but still filled with grandeur, mystery, and awesome spectacle. Astronomy is an endeavour pursued by professionals, but also enjoyed by millions of amateurs worldwide, enabled by easy access to telescopes that Galileo would have loved to spend a few long evenings with, sweeping the heavens.  For professionals and amateurs alike, we still celebrate the ritual of a telescope’s first night out under the stars.

First light. It is a magical time for any telescope — the first time it gathers starlight, and rather than let that light be absorbed by the Earth and pass into oblivion, it redirects it to a human eye, carrying the tales of the far away Cosmos.  On a cool autumn evening, nestled down amongst the mountains of northern Utah, I turned a new telescope skyward for the first time. First light.  The telescope was one of my own making, which I built based on the wisdom of others who had built telescopes before me, much like Galileo.  I named it Cosmos Mariner.

My two telescopes. “Equinox” on the left, and “Cosmos Mariner” on the right.

Mariner is much larger than Galileo’s original telescope, and its optical elements were fabricated with higher precision than Galileo could have hoped to achieve in those early days.  All told, Cosmos Mariner will gather about 500 times more light than Galileo’s original telescope, and can see objects about 25,000 times fainter than Galileo.  And what awesome spectacles we beheld!

The first sight of the sky was the double star Albireo.  The “head” of the constellation Cygnus, the Swan, Albireo lies nearly overhead as darkness falls at this time of year. It is a beautiful stellar pair, notable because it shows a striking amount of color — one star glows with a deep, yellow hue, while the other appears as a brilliant blue.  My six year old daughter dutifully climbed the ladder, participating in this special night but perhaps not really knowing what to expect.  She leaned over to the eyepiece and peered in.  Through the gathering darkness, I heard her exclaim: “Pop! They have colors!”  I could have quit then; First Light was a success.  I often think back to that first night when Galileo turned his telescope to the sky for the first time.  What did he look at?  Was he by himself, or was someone there with him to share in the wonder and the spectacle?

The double star, Albireo (beta Cygni).

Our next stop was nearby, off the wing tip of Cygnus.  There, nestled against the backdrop of the star studded Milky Way, a telescope will reveal the faint, gossamer light of the Veil Nebula.  Peering through Mariner’s great eye, we could see faint tendrils and thin tracers of light, woven together in an intricate web of gas.  The Veil Nebula is part of a much greater complex in the sky called the Cygnus Loop.  It is a supernova remnant — the gaseous remains of a star that died in a titanic explosion some 8000 years ago.  It is a doleful reminder that the stars also die, but that the Cosmos is beautiful and delicate even during the throes of destruction.  The death of the stars is the beginning of new birth in the Cosmos — supernova explosions create the complex chemical elements that make up worlds like the Earth and beings like you and I.  The gas and dust that we see today as the Veil Nebula will someday merge with other vast clouds in the Milky Way and collapse under gravity’s inexorable pull until it explodes with the birth a thousand new suns.

The eastern portion of the Veil Nebula.

Our last stop of the evening was high in the eastern sky, nestled just below the neck of Pegasus.  Turning Mariner’s gaze toward that distant corner of the sky revealed the diaphanous glow of a galaxy that astronomers call NGC 7448.  Mariner revealed a faint, glowing oval of light with a brighter orb of luminosity embedded at its center — a spiral galaxy, not unlike our own home, the Milky Way.  There are other brighter galaxies in the sky to see, but on this night I wanted to see this galaxy, because the light from that distant island of stars left its home 100 million years ago, departing for Earth at a time when dinosaurs still roamed our small blue world.  It astonishes me still that I can just now capture that light tonight, drinking in the photons through my eyes, and converting them into evanescent memories.

The spiral galaxy, NGC 7448, 100 million light years away from Earth.

The telescope is magic in its rarest and purest form, a device brought to life by human ingenuity and creativity.  Telescopes expand our vision beyond the small confines of our world to distant corners of the Cosmos, showing us vistas that challenge the boundaries of ordinary human comprehension and force us to think deeply about our place in the grand design.

The great secret of telescopes is that they all will show you more of the Cosmos than your eyes alone will.  The cheap pair of $10 binoculars you have under the seat of your car is a far superior astronomical instrument than Galileo’s original telescope.  For the cost of two or three months of your cell phone bill, you can own a 6-inch telescope that will reveal thousands of distant galaxies, swirling nebulae, the enigmatic surface of Mars, and the beautiful choreography of binary stars.  Large telescopes, like Mariner, are becoming more and more common, providing views that would have made Galileo swoon.

Take a moment tonight, and go out and look at the stars.  Turn off your back porch light, and drink in the starlight that has been hurtling toward the Earth since before you were born.  Make your own First Light, and ponder the deep connection we share with the Cosmos.  And if you’re ever in my neck of the woods, let me know; we’ll pull Mariner out and celebrate in the starlight together.