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Are we really star-stuff from the interior of collapsing stars?

Are we really star-stuff from the interior of collapsing stars?

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Carl Sagan has said several times that we are "star-stuff".

One instance can be found in Good Reads' Carl Sagan > Quotes > Quotable Quote:

The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were made in the interiors of collapsing stars. We are made of starstuff.

Question: Was most of my nitrogen really made in the interior of a star during its collapse? Was my calcium and iron made there as well, and not (for example) in an expanding shell after a supernova?

The straightforward answer is, "Yes, we are made of star stuff."

Some of it will be from the interior of collapsing stars, some will be from supernovas, some from normal everyday fusion, and some from other processes.

The answers from @HDE226868 and @RobJeffries on this question on where heavier elements come from gives good background, including this nugget:

The split between r-process and s-process production of heavier than iron (peak) elements is about 50:50. ie They weren't mainly made in supernovae, which is a frequent, incorrect claim.

but of most importance is Rob's final point:

The relative contributions of various sites to the r-process remains an unsettled matter. You could also read my answers on this topic in Physics This Site.

On following Rob's links I think this provides you with an excellent overall answer (and relative percentages)

A more up-to-date visualisation of what goes on (produced by Jennifer Johnson) and which attempts to identify the sites (as a percentage) for each chemical element is shown below. It should be stressed that the details are still subject to a lot of model-dependent uncertainty.

Looking at C and N - the majority seems to be from dying low mass stars, and Ca and Fe are from exploding stars, which indicates that Carl is not far off the mark.

Sagan's quote is half-correct. While some of these elements are created during or immediately prior to a supernova of some sort, others are either partially or entirely fused during normal stellar nucleosynthesis. Nitrogen falls into the latter category, whereas calcium and iron have one foot in each. On the whole, though, calling these elements "starstuff" is pretty accurate.


My answer serves largely to complement Rory's, and to address the issue of nitrogen production in particular, partly since there is some disagreement as to how much high-mass stars produce. It is thought that the majority of nitrogen is produced in the carbon-nitrogen-oxygen (CNO) cycle, which includes the subprocess originally known as the CN cycle. The CNO cycle is only dominant in stars more massive than the Sun, partly because the energy generation rate is much more sensitive to temperature than the proton-proton chain (scaling as $epsilonsim T^{20}$, compared to $epsilonsim T^4$), largely because the Coulomb barrier is much higher for the CNO cycle.

Intermediate-mass AGB stars, with masses in the vicinity of $5M_{odot}$, enrich the interstellar medium with nitrogen through strong stellar winds (1, 2), and are thought to be the most important contributors to nitrogen synthesis. AGB stars are post-main sequence stars that have ascended the red giant branch and are now large and luminous, undergoing shell burning of helium and hydrogen. Their high mass-loss rates are responsible for the enrichment, and most of this mass loss happens before the planetary nebula phase; therefore, I'd be reluctant to characterize the sources of nitrogen as even dying stars. They're simply old, evolved intermediate-mass stars - still not massive enough to undergo supernovae, but also not true low-mass stars.

In short, the answer to the nitrogen question is no, most nitrogen in the universe was not made from supernova nucleosynthesis, but was indeed made by lower-mass stars, in particular intermediate-mass AGB stars. The contributions of supernovae are, as indicated above, not agreed upon.


Calcium can indeed be produced via nucleosynthesis in massive stars, usually via silicon- and oxygen- based pathways that synthesize $^{40} ext{Ca}$, a common calcium isotope. Recently, discoveries of calcium-rich supernovae have indicated that those could be substantial contributors to calcium abundances. The characteristics of the progenitors are not yet known; they could be low-mass white dwarfs accreting matter from a companion, compact objects colliding, or higher-mass stars undergoing traditional core collapse supernovae. We don't have enough data to determine what the contribution of these supernovae is to calcium production, although it's being worked on.


Much of the iron produced by stars is in the form of the isotope $^{56} ext{Fe}$, which is one of the end results of silicon burning in the extreme late stages (essentially the last day or so) of a high-mass star's life, as well as in supernovae. $^{56} ext{Ni}$ is initially synthesized but decays to $^{56} ext{Co}$ and eventually $^{56} ext{Fe}$.

As It Turns Out, We Really Are All Starstuff

"The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were made in the interiors of collapsing stars," Carl Sagan famously said in his 1980 series Cosmos. "We are made of starstuff."

Above: Hubble image of the Crab Nebula supernova remnant captured with the Wide Field and Planetary Camera 2. Credit: NASA, ESA, J. Hester and A. Loll (Arizona State University)

And even today, observations with NASA's airborne SOFIA observatory are supporting this statement. Measurements taken of the dusty leftovers from an ancient supernova located near the center our galaxy – aka SNR Sagittarius A East – show enough "starstuff" to build our entire planet many thousands of times over.

"Our observations reveal a particular cloud produced by a supernova explosion 10,000 years ago contains enough dust to make 7,000 Earths," said research leader Ryan Lau of Cornell University in Ithaca, New York – the same school, by the way, where Carl Sagan taught astronomy and space science.

Above: Composite image of SNR Sgr A East showing infrared SOFIA data outlined in white against X-ray and radio observations. (NASA/CXO/Herschel/VLA/Lau et al.)

While it's long been known that supernovae expel enormous amounts of stellar material into space, it wasn't understood if clouds of large-scale dust could withstand the immense shockwave forces of the explosion.

These observations, made with the joint NASA/DLR-developed Faint Object InfraRed Camera for the SOFIA Telescope ( FORCAST ) instrument, provide key "missing-link" evidence that dust clouds do in fact survive intact, spreading outward into interstellar space to seed the formation of new systems.

Above: NASA's Stratospheric Observatory for Infrared Astronomy (SOFIA) aircraft (Credit: NASA/Jim Ross)

Interstellar dust plays a vital role in the evolution of galaxies and the formation of new stars and protoplanetary discs – the orbiting "pancakes" of material around stars from which planets (and eventually everything on them) form.

The findings may also answer the question of why young galaxies observed in the distant universe possess so much dust it's likely the result of frequent supernova explosions from massive early-generation stars.

"We have begun to contemplate our origins: starstuff pondering the stars organized assemblages of ten billion billion billion atoms considering the evolution of atoms tracing the long journey by which, here at least, consciousness arose."

– Carl Sagan, Cosmos (1980)

This post by Jason Major originally appeared at Universe Today and has been republished with permission. Read the original here .

Here are 60 Carl Sagan Cosmos and Love Quotes. An American Astrophysicist Best Known as the Author of Cosmos and Pale Blue Dot.

The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were made in the interiors of collapsing stars. We are made of star stuff.

We are like butterflies who flutter for a day and think it is forever.

Imagination will often carry us to worlds that never were. But without it we go nowhere.

What a marvelous cooperative arrangement – plants and animals each inhaling each other’s exhalations, a kind of planet-wide mutual mouth-to-stoma resuscitation, the entire elegant cycle powered by a star 150 million kilometers away.

We make our world significant by the courage of our questions and the depth of our answers.

Exploration is in our nature. We began as wanderers, and we are wanderers still. We have lingered long enough on the shores of the cosmic ocean. We are ready at last to set sail for the stars.

For me, it is far better to grasp the universe as it really is than to persist in delusion, however satisfying and reassuring.

There’s as many atoms in a single molecule of your DNA as there are stars in the typical galaxy. We are, each of us, a little universe.

Knowing a great deal is not the same as being smart intelligence is not information alone but also judgement, the manner in which information is coordinated and used.

What an astonishing thing a book is. It’s a flat object made from a tree with flexible parts on which are imprinted lots of funny dark squiggles. But one glance at it and you’re inside the mind of another person, maybe somebody dead for thousands of years.

Somewhere, something incredible is waiting to be known.

When we look up at night and view the stars, everything we see is shining because of distant nuclear fusion.

The Cosmos is all that is or was or ever will be. Our feeblest contemplations of the Cosmos stir us — there is a tingling in the spine, a catch in the voice, a faint sensation, as if a distant memory, of falling from a height. We know we are approaching the greatest of mysteries.

If I finish a book a week, I will read only a few thousand books in my lifetime, about a tenth of a percent of the contents of the greatest libraries of our time. The trick is to know which books to read.

You are worth about 3 dollars worth in chemicals.

We humans look rather different from a tree. Without a doubt we perceive the world differently than a tree does. But down deep, at the molecular heart of life, the trees and we are essentially identical.

A galaxy is composed of gas and dust and stars – billions upon billions of stars. Every star may be a sun to someone.

It is said that men may not be the dreams of the god, but rather that the gods are the dreams of men.

Every thinking person fears nuclear war, and every technological state plans for it. Everyone knows it is madness, and every nation has an excuse

By looking far out into space we are also looking far back into time, back toward the horizon of the universe, back toward the epoch of the Big Bang.

Astrology: What is it, how does it work, and why does it work

Ann Cortese , BS. , MPS

Ann Cortese has been a Professional Astrologer and Counselor for 40 years, Member of NCGR, ISAR and past member of AFAN and AFA served as Board Member of the NCGR Fairfield Connecticut Chapter of NCGR and studied under Charles and Vivia Jayne, Donald Yott and Meria Epstein of New York City. Taught Astrology and a five year course in Tibetan Buddhism for the MCNJ, teaches astrology classes and gives private instructions, lectures, holds group readings. Private practice includes personalized taped readings for clients. Available for Natal Chart, Solar Return, Present Transits, Sec. Progressions and Solar Arc, and Compatibility readings. Gift certificates available. All readings include a Meditation CD.

Are you Curious about the secrets of the STARS? Would you like to learn how the Zodiac can come alive and aid you in achieving your goals, lead you to a path of personal growth and spiritual development?

Would you like to know how conflicting energies can be transmuted into positive action and change your relationship into the relationship of your dreams? Would you like to explore the Universe within?

Come along then, walk with me as we learn the language of the stars, find out how you and a “significant other” can dance to the music of the spheres. Come along and learn what Astrology is, how it works, why it works. Come join with me in achieving your personal goals, stimulate your creativity, and open up new vistas of life thereby leading to the fulfillment of your dreams.

What is Astrology?

Astrology is a combination of two disciplines: it is a science and an art.

It is a spiritual science, a blueprint for our Spiritual Growth, denoting the relationship between the personal universe within and the larger universe outside of oneself: the Cosmic Universe.

It is in the construction of the individual Astrological chart that we recognize that Astrology is a tightly knit, logical, precise mathematical science. The astrological chart is constructed by the use of specific coordinates of the Longitude and Latitude of the individual’s geographic place of birth, the individual’s time of birth, the time difference between Greenwich, England and the place of birth, and other mathematical coordinates.

In interpreting the horoscope, the mathematical aspects of the relationship of the planets to one another is used. The main aspects are planets squaring one another by of 90 degrees, trines of 120 degrees, sextiles of 60 degrees inconjuctions of 150 degrees and oppositions of 180 degrees. In addition to the main aspects other degree aspects are also considered. In certain types of readings, namely the directed solar arc, the arc of the sun is calculated in relation to the planet placements and the angles of horoscope.

Once the chart is established mathematically, the interpretive art of the reading comes into play. Interpretation is not only an art but it requires sensitivity and skill to present the reading in such a way that allows the client to come to their own realization of the work that needs to be done to develop their personal, spiritual, emotional and intellectual growth. The Astrologer is, in effect, a catalyst to assist the client to achieve that end. The Natal Chart can be likened to a road map. It is a living breathing entity, identifying areas where we can, by use of free will, transform our lives.
The Natal Chart shows us our life’s trends, our weaknesses and strengths, and where conflicting, or negative energies may manifest. The Professional Astrologer, through years of study and research, can make certain deductions regarding upcoming trends. By determining the position of the planets within specific houses, signs the planets are in, and the mathematical relationship of one planet to another, he/she can make certain deductions and recommendations regarding the possible use of these energies. We must be cognizant of the fact that the planets only cast energy. It is we who, by virtue of the choices we make in the use of those energies, allow them to manifest in a positive or negative manner. Through the casting of the chart and studying it, and interpreting it the Astrologer is able to grasp where the client stands on their path of evolution. A working definition of Astrology could well be, “It is a unique system of the interpretation of planetary action and the resulting interaction it produces in the human experience.” For everything there is a season. A time to love and a time to hate. A time to live and a time to die. Life is cyclical. Planetary movement is cyclical. The secret of an astrological reading is the secret of time: a given moment in time. Carl Jung said,

“Whatever is born in this moment of time has the quality of this moment in time.”

Are these aspect of Astrology open to question?

Yes, of course, The theories of some of the great Psychologists such as Freud, Jung, Maslow and others are still being debated, questioned, interpreted and reinterpreted…and ….as in the science of Astronomy, the mysteries of our very existence in the Universe are still being pondered and questioned. While there has been much progress made to enlighten us with regard to planets in our galaxy, many remain that may never be solved.


Astrology has a language of its own. It is a language of symbols that represent the planets, the signs of the Zodiac and the mathematical aspects between the planets. The Horoscope, or the Natal Chart, can be likened to a road map. It delineates how you can get from point to another, from one level of growth to the next. Some of the roads are clearly marked, smooth and easy to travel over, Other roads may be in poor condition, needing repair, while still others may be insurmountable and may need complete restructuring-or- may call for a complete change of direction. The Horoscope is a blue print of our character and our potential for both spiritual and personal growth. It can help us identify where we can transform our lives. The chart shows what CAN happen NOT what will happen. We must keep in mind that Man has free will in making choices.

The Horoscope is a blue print of our character and our potential for both spiritual and personal growth. It can help us identify where we can transform our lives. The chart shows what CAN happen NOT what will happen. We must keep in mind that Man has free will in making choices.

The Horoscope shows: Life trends, Points of Strengths, Weakness, Conflicting energies, (two energies at cross purposes) areas of the ability to succeed.

What can you learn from a Horoscope reading?

1. You can learn about your character, your personality, how to make changes in your character and learn how by changing your character you can change your destiny.

2. You can become aware of up coming trends in your life and prepare for the challenging ones and cash in on the beneficial ones.

3. You will learn about the use of Yin and Yang energies, every planet and aspect has a positive and negative energy….the Yin and the Yang.

4. You will learn to listen to your inner voice and thereby raise the level of your consciousness.

5. By raising your level of consciousness you will view the people and the world around you in a different light.

As a bookkeeping system, Astrology has 3 ledgers:

A Debit Ledger: The result of a depleted spiritual bankbook, better known as Karma.
A Credit Ledger: The result of cumulative good works, the conformity to the essential nature of ones own character: to thine own self be true.
General Ledger: in which we find the Capital Gains the Spiritual Bank Book that has earned income from past lives.


In the immortal words of Carl Sagan ( a distinguished Cornell University Astronomer, Pulitzer Prize Winner, and author) “we are star stuff”. In his book entitled “Cosmos” ( which appeared on the New York Times Best Seller List for 70 weeks) he devoted a whole 27 page chapter to “ The Lives of the Stars”’ he says and I quote, “The Nitrogen in our DNA, the calcium in our teeth, the iron in our blood and the carbon in our apple pies are all made of the interiors of collapsing stars. We are made of star stuff. We are a carbon-based life form. We are, in the most profound sense, children of the cosmos.” Since the time of Johannes Kepler and Isaac Newton scientists have sought to deduce a connection between terrestrial magnetic phenomena and celestial phenomena. It has since been found that there is indeed a scientific correlation between planting crops with the lunar phases of the moon and the more bountiful yields of crops. There is no seed or plant that will not respond to a magnetic field by remendous acceleration in growth. The Earth’s magnetism activates an enzyme system in fruits and vegetables that can trigger a loss or gain of protons which speed up the enzyme process and causes ripening.

In 1962, DR. Robert O. Becker of the V.A. Hospital in Syracuse, N.Y., claimed that the Astronauts who invade the magnetic force field of other planets between the Earth’s atmosphere will exhibit aberrations. This proved true with both the American and Russian Astronauts. Dr. Becker found that the electromagnetic field in our environment has a profound effect on behavior and biological cycles. He has shown concrete evidence that psychotic breakdowns correlate with variations in the Earth’s magnetic field and have a direct effect on the admissions to mental hospitals. In the esoteric field we call this electromagnetic field “an aura.” It has also been found that electro magnetic therapy has been used in the treatment of advanced cancer, on third degree burns over the entire human body, and when a human organism is exposed to two lines of powerful magnetic forces intersecting at right angles the effects can be disastrous. There is a sense of structure and order in the Universe and there is a structure and order in Astrology. So, where then is the dividing line between the scientific and the esoteric? Is there one at all?

I would be remiss if I did not mention that for centuries Astrology fell into disrepute because like so many things on Earth it fell into the wrong hands and was used as a fortune telling gimmick. People were exploited by the Astrologers-or- Seers who were seeking to gain from it instead of to give through it. The Spiritual Astrologer is one who aspires to Higher Law. The spiritual Astrologer knows that he/she is only a channel through which the Higher Power flows: a mere catalyst in assisting to raise the level of consciousness of those who are seeking to evolve in their personal and spiritual development. The Spiritual Astrologer knows that the ALL is in all…..All the answers to all our questions, our dilemmas are all inside. The Spiritual Astrologer knows that everything is created inwardly and then projected into the world of manifestation. The Spiritual Astrologer becomes the Healing Agent in the process of assisting the individual in accessing the answers from within. In conclusion, we can postulate-or-claim that the movement of all things in the Universe is correlated: everything is in a systematic relationship to everything else –or- to each other.. This is the reason Astrology is what it is, how it works and why it works.

We Are Made of Star-Stuff

Dear Quote Investigator: The chemical elements of life such as carbon, magnesium, and calcium were originally created in the interior furnaces of stars and then released by stellar explosions. This fact can be expressed with a beautiful poetic resonance. Here are three examples:

We are made of star-stuff.
Our bodies are made of star-stuff.
There are pieces of star within us all.

I think the well-known astronomer and science communicator Carl Sagan said this. Would you please trace this expression? Was Sagan the first person to say this?

Quote Investigator: In 1973 Carl Sagan published “The Cosmic Connection: An Extraterrestrial Perspective” which included the following passage. Boldface has been added here and below: 1

Our Sun is a second- or third-generation star. All of the rocky and metallic material we stand on, the iron in our blood, the calcium in our teeth, the carbon in our genes were produced billions of years ago in the interior of a red giant star. We are made of star-stuff.

Sagan was an important locus for the dissemination of this expression however, it has a long history. An interesting precursor appeared in a North Carolina newspaper in 1913. A columnist pointed out that the Sun and Earth were made of star-stuff. This implied that humans were also made of star-stuff, but this was not directly stated: 2

The spectroscope analyzes the light if you please, and shows what it is made of. What was the surprise of the tireless searchers when they found common earth metals burning in the mighty sun!

There was once a little girl who cried out with joy when she realized for one little moment that the earth is truly a heavenly body, and that no matter what is happening to us we are really living right up among the stars. The sun is made of “star stuff, and the earth is made of the same material, put together with a difference.

In 1918 the President of the Royal Astronomical Society of Canada delivered a speech with the phrase “our bodies are made of star-stuff”, and he seemed to be reaching for a quasi-spiritual interpretation for this fact: 3

It is true that a first thoughtful glimpse of the immeasurable universe is liable rather to discourage us with a sense of our own insignificance. But astronomy is wholesome even in this, and helps to clear the way to a realization that as our bodies are an integral part of the great physical universe, so through them are manifested laws and forces that take rank with the highest manifestation of Cosmic Being.

Thus we come to see that if our bodies are made of star-stuff,—and there is nothing else, says the spectroscope, to make them of—the loftier qualities of our being are just as necessarily constituents of that universal substance out of which are made

“Whatever gods there be.”

We are made of universal and divine ingredients, and the study of the stars will not let us escape a wholesome and final knowledge of the fact.

Here are additional selected citations in chronological order.

In 1921 a newspaper in Michigan introduced a new columnist with an advertisement that highlighted a version of the adage: 4

We’re All Made of Dust—
But It’s Star Dust!

Some comfort in that, says Dr. William E. Barton, the new contributor to The Evening News.

Astronomers know how to tell what sort of stuff those stars are made of—and how one bright speck up there in the sky lacks something other stars have.

Odd, though, that human beings have in their makeup about ALL the different elements of ALL those stars.

You’ll be interested in this, as Dr. Barton tells it—and in his comment, putting new zest in life for every human that’s made of star-stuff.

In 1929 the New York Times printed an article titled “The Star Stuff That Is Man” on the first page of the magazine section. The astronomer Harlow Shapley, director of Harvard College Observatory, was interviewed and stated the following: 5

We are made of the same stuff as the stars, so when we study astronomy we are in a way only investigating our remote ancestry and our place in the universe of star stuff. Our very bodies consist of the same chemical elements found in the most distant nebulae, and our activities are guided by the same universal rules.

The last statement of the article was also used as a caption for the illustration depicting a human figure with a backdrop of planets and galaxies:

We Are Made of Star Stuff and Are Part of a Magnificent Creation.

In 1971 the Nobel Laureate Doris Lessing touched on this theme in her novel “Briefing for a Descent into Hell”: 6

No one knows what has existed and has vanished beyond recovery, evidence for the number of times Man has understood and has forgotten again that his mind and flesh and life and movements are made of star stuff, sun stuff, planet stuff

In 1973 Carl Sagan published a book with the following statement as noted previously in this article:

We are made of star-stuff.

In 1978 “The Seven Mysteries of Life” by Guy Murchie was published. The book stated that “Most of the matter in the universe in fact is now known to pass at some time through the caldron of the stars.” Murchie included an intriguing adage that he labeled an “ancient Serbian proverb”. QI does not currently have adequate research tools for determining the age of this proverb: 7

When you can really grasp the universality of such relationships you have gained a new insight into the ancient Serbian proverb: “Be humble for you are made of dung. Be noble for you are made of stars.

In 1980 the landmark science series “Cosmos: A Personal Voyage” was televised, and Carl Sagan was the host and a co-writer. The first episode was titled “The Shores of the Cosmic Ocean”, and it included the following words spoken by Sagan: 8

The surface of the Earth is the shore of the cosmic ocean. On this shore we’ve learned most of what we know. Recently, we’ve waded a little way out, maybe ankle-deep, and the water seems inviting. Some part of our being knows this is where we came from. We long to return, and we can because the cosmos is also within us. We’re made of star stuff. We are a way for the cosmos to know itself.

In 1981 the writer Vincent Cronin published “The View from Planet Earth”, and it included a version of the adage: 9

Our bodies contain three grams of iron, three grams of bright, silver-white magnesium, and smaller amounts of manganese and copper. Proportionate to size, they are among the weightiest atoms in our bodies, and they come from the same source, a long-ago star. There are pieces of star within us all.

In 2006 the well-known skeptic Michael Shermer credited Sagan with the saying: 10

How can we connect to this vast cosmos? Sagan’s answer is both spiritually scientific and scientifically spiritual “The cosmos is within us. We are made of star stuff,” he said, referring to the stellar origins of the chemical elements of life, which are cooked in the interiors of stars, then released in supernova explosions into interstellar space where they condense into a new solar system with planets, some of which have life that is composed of this star stuff.

In conclusion, Carl Sagan did employ a version of this saying by 1973. But the expression was in circulation decades before this. The astronomer Albert Durrant Watson used a version in a speech in 1918. In 1973 an interesting thematically related proverb appeared in a book together with the claim that the words were ancient. But the proverb’s accurate age is currently not known to QI.

(Special thanks to Joseph M. Moreno who inquired about the quotation credited to Vincent Cronin. Also, special thanks to Lim Pin who asked about the proverb categorized as Serbian.)

Cynthia Leitich Smith

Cynthia Leitich Smith is a NYTimes bestselling, award-winning children’s-YA author and writing teacher.

Every Cell In Your Body Is Infused With The Collapse Of A Star (VIDEO)

Living shoulder-to-shoulder on a small blue planet zooming through an ever-expanding universe, it's easy to feel very, very small. But what we are is actually pretty incredible.

"We are dead stars looking back up at the sky," Dr. Michelle Thaller, astronomer and science communicator at NASA's Goddard Space Flight Center, says in a recent video (above) posted by The Atlantic.

Every single cell in our bodies contains elements created in the burning center of a collapsing star -- from the iron in our blood to every bit of calcium in our bones and keratin in our hair. That's because in the very early days of the universe that followed the Big Bang, only the simplest elements existed, like hydrogen.

"The only thing in the universe that can make a bigger atom is a star," Thaller says. "The entire periodic table, every element you've ever heard of, was processed inside the body of a star. And that star then unraveled or exploded, and here we are." Watch the video above to learn more.

It's like what celebrated astrophysicist Neil deGrasse Tyson has said, echoing Carl Sagan: if you feel insignificant given the immensity of the cosmos, you're not looking at it in the right way. "We are not just figuratively but literally made of stardust."

And that is no small thing.

Confirmed: We Really are ‘Star Stuff’

Scientist Carl Sagan said many times that “we are star stuff,” from the nitrogen in our DNA, the calcium in our teeth, and the iron in our blood.

It is well known that most of the essential elements of life are truly made in the stars. Called the “CHNOPS elements” – carbon, hydrogen, nitrogen, oxygen, phosphorous, and sulfur – these are the building blocks of all life on Earth. Astronomers have now measured of all of the CHNOPS elements in 150,000 stars across the Milky Way, the first time such a large number of stars have been analyzed for these elements.

“For the first time, we can now study the distribution of elements across our Galaxy,” says Sten Hasselquist of New Mexico State University. “The elements we measure include the atoms that make up 97% of the mass of the human body.”

Astronomers with the Sloan Digital Sky Survey made their observations with the APOGEE (Apache Point Observatory Galactic Evolution Experiment) spectrograph on the 2.5m Sloan Foundation Telescope at Apache Point Observatory in New Mexico. This instrument looks in the near-infrared to reveal signatures of different elements in the atmospheres of stars.

Quote from Carl Sage. Credit: Pinterest

While the observations were used to create a new catalog that is helping astronomers gain a new understanding of the history and structure of our galaxy, the findings also “demonstrates a clear human connection to the skies,” said the team.

While humans are 65% oxygen by mass, oxygen makes up less than 1% of the mass of all of elements in space. Stars are mostly hydrogen, but small amounts of heavier elements such as oxygen can be detected in the spectra of stars. With these new results, APOGEE has found more of these heavier elements in the inner part of the galaxy. Stars in the inner galaxy are also older, so this means more of the elements of life were synthesized earlier in the inner parts of the galaxy than in the outer parts.

So what does that mean for those of us out on the outer edges of one of the Milky Way’s spiral arms, about 25,000 light-years from the center of the galaxy?

“I think it’s hard to say what the specific implications are for when life could arise,” said team member Jon Holtzman, also from New Mexico State, in an email to Universe Today. “We measure typical abundance of CHNOPS elements at different locations, but it’s not so easy to determine at any given location the time history of the CHNOPS abundances, because it’s hard to measure ages of stars. On top of that, we don’t know what the minimum amount of CHNOPS would need to be for life to arise, especially since we don’t really know how that happens in any detail!”

Holtzman added it is likely that, if there is a minimum required abundance, that minimum was probably reached earlier in the inner parts of the Galaxy than where we are.

The team also said that while it’s fun to speculate how the composition of the inner Milky Way Galaxy might impact how life might arise, the SDSS scientists are much better at understanding the formation of stars in our Galaxy.

“These data will be useful to make progress on understanding Galactic evolution,” said team member Jon Bird of Vanderbilt University, “as more and more detailed simulations of the formation of our galaxy are being made, requiring more complex data for comparison.”

Sloan Foundation 2.5m Telescope at Apache Point Observatory. Credit: SDSS.

“It’s a great human interest story that we are now able to map the abundance of all of the major elements found in the human body across hundreds of thousands of stars in our Milky Way,” said Jennifer Johnson of The Ohio State University. “This allows us to place constraints on when and where in our galaxy life had the required elements to evolve, a sort ‘temporal Galactic habitable zone’”.

The catalog is available at the SDSS website, so take a look for yourself at the chemical abundances in our portion of the galaxy.

#2 Spread Out

When this explosion happens, most of the elements that the star has created are blown out into the atmosphere.

All of these random elements spread out aimlessly in all directions and become things like planets, or galaxies, or … people.

You see, since the very beginning of the universe, stars have been continually born, died, and reborn again. This endless cycle is what created everything we know in our universe.

And, since stars have been around for over 13 billion years, compared to humans’ 200 thousand year existence, they are like our ancestors.

The next time you gaze up into the night sky, just think, one of those stars you see might have produced the elements that your body is made of.


Whatever this thing is, it is not a supernova. Had the object been destroyed, the light would be fading. I can think of two alternate possibilities: gravitational lensing and beaming. Lensing could take an already bright object and make it look even brighter. However, the explanation leads to all sorts of issues: What is the lensing object? What is the object being lensed? How is it that the one-behind-the-other arrangement is holding over a highly extended period of time? Given that this is not visible as an Einstein ring, the lensing object must be relatively small, and that makes the last question (about the arrangement holding) a very good one. So lensing, while possible, is unlikely.

On the other hand, beaming from a gravitationally collapsed object (or "black hole") could explain this. If the beam is pointed directly at the Earth, it could be appearing as a bright point. If the photons are being preferentially sent in our direction, the amount of energy needed to power this ongoing "event" would be much smaller than for an isotripically bright supernova. This would still be a powerful source, but it is not like a permanent "supernova". So, is the light curve compatible with what is observed in active galactic nuclei (which may be bigger versions of this kind of thing)? Is there evidence of blue-shifting (as the stuff emitting the light must be being beamed towards us at high speeds)? Even this raises questions, such as whether this type of thing should be rare enough to not have been observed before.

Overall, I find an explanation where the energy of the event is being directed towards Earth to be better than our seeing a "supernova" than will not die.

Watch the video: Were All Made of Stardust. Heres How. (January 2023).