Across the Universe: Happy Birthday to Us

This column first ran in The Tablet in March 2016

We celebrated last year's anniversary with a cake!

It has been a month of anniversaries.

Exactly four hundred years ago (2016) Galileo first got into hot water with the Church over the Copernican system. Starting with a hearing of the Holy Office on 23 February, the affair stretched across all of spring 1616 including Galileo’s meeting with Cardinal Bellarmine on 26 February, and the formal censure of Copernicus’ work issued on 5 March. Curiously, Galileo’s works were not mentioned at that time.

(It wasn’t Galileo’s first run-in with the Church. In 1604 he had been turned in to the Inquisition by his mother, who didn’t like the bad names he’d called her or the fact that he’d skip Mass to spend time with his courtesan girlfriend, later mother to his three children.)

By the end of the 19th century, of course, the Church view on astronomy had changed. Pope Leo XIII in his encyclical Aeterni Patris (1879) essentially endorsed Galileo’s view on science and religion. And on 14 March 1891, 125 years ago  (2016), Pope Leo promulgated a “Motu Proprio” that established the modern Vatican Observatory. Two months later, his encyclical Rerum Novarum would mark a new beginning of the Church’s engagement with the modern world.

Finally, just thirty years ago  (2016) this month, on 15 March 1986, the Vatican Secretariat of State informed the Vatican Observatory that Pope John Paul II had given his blessing to build the Vatican Advanced Technology Telescope. Since then, that telescope on a remote Arizona mountaintop has been our mainstay for astronomical observations.

Birthdays and anniversaries are a time to reflect on where we’ve been and how we’ve changed over the years. At the time of Galileo, astronomy meant cosmology, the philosophical basis of how we understood our place in the universe. Thus questions of astronomy took on a philosophical and theological significance.

But our cosmological ideas moved from Copernicus’ fixed sun, through Kepler’s elliptical orbits, to Kant’s idea of galaxies as island universes and Herschel’s measurement of our place in the Milky Way. Our modern speculations about multiple universes carry as much a tinge of science fiction as of natural philosophy. One lesson I hope we’ve learned is that no modern cosmology is a good basis for theological doctrine, simply because no matter how well founded our astronomy is we can expect it will eventually go out of date.

What is striking to me is the development of the Church’s attitude towards astronomy. After the Galileo affair showed the danger of too-close ties between science and theology, Pope Leo XII’s reasons to establish an observatory were primarily as a way of shoring up the reputation of the Church. He was responding to the late Victorian view that science and religion were somehow inevitably at war, a quaint idea held today only by journalists and the occasional elderly Oxford biologist.

Over the last hundred years, however, the emphasis of the Church’s role in astronomy has changed from mere public relations to a recognition that astronomy is a Good Thing in its own right, as a way of coming closer to the Creator. One of the earliest examples of this attitude can be found in an address of Pope Pius XII to the Pontifical Academy of Sciences in 1939, where he mused, “Man ascents to God by climbing the ladder of the Universe.”

Closing the loop, in 2008 Pope Benedict XVI approved how “Galileo saw nature as a book whose author is God, in the same way that Scripture has God as its author.” Of course, this echoes St. Paul’s Letter to the Romans: “Since the beginning of time, God has revealed Himself in the things He has created.”

Also in Across the Universe

  1. Across the Universe: What’s in a Name?
  2. Across the Universe: Fools from the East
  3. Across the Universe: Hunches
  4. Across the Universe: Desert or a dessert?
  5. Across the Universe: Stardust messages
  6. Across the Universe: The best way to travel
  7. Across the Universe: Original Proof
  8. Across the Universe: Pearls among Swine
  9. Across the Universe: One Fix Leads to Another
  10. Across the Universe: Limits to Understanding
  11. Across the Universe: The Glory of a Giant
  12. Across the Universe: Fire and Ice
  13. Across the Universe: Science as Story
  14. Across the Universe: Recognition
  15. Across the Universe: Tending Towards Paganism
  16. Across the Universe: The Ethics of Extraterrestrials
  17. Across the Universe: Orbiting a New Sun
  18. Across the Universe: Seeing the Light
  19. Across the Universe: DIY Religion
  20. Across the Universe: Truth, Beauty, and a Good Lawyer
  21. Across the Universe: Techie Dreams
  22. Across the Universe: By Paper, to the Stars
  23. Across the Universe: Transit of Venus
  24. Across the Universe: Ordinary Time
  25. Across the Universe: Deep Impact
  26. Across the Universe: New Worlds
  27. Across the Universe: Tom Swift and his Helium Pycnometer
  28. Across the Universe: Tradition… and Pluto
  29. Across the Universe: Bucks or Buck Rogers?
  30. Across the Universe: Key to the Sea and Sky
  31. Across the Universe: Off The Beach
  32. Across the Universe: All of the Above
  33. From the Tablet: Tales of Earthlings
  34. Across the Universe: Heavenly peace?
  35. Across the Universe: Help My Unbelief
  36. Across the Universe: Stories of Another World
  37. Across the Universe: Planetary Counsels
  38. Across the Universe: Words that Change Reality
  39. Across the Universe: New Heavens, New Earth
  40. Across the Universe: Souvenirs from Space
  41. Across the Universe: For the love of the stars…
  42. Across the Universe: Spicy planet stories
  43. Across the Universe: Asking the right questions
  44. Across the Universe: Everything You Know Is Wrong
  45. Across the Universe: Errata
  46. Across the Universe: Clouds of Unknowing
  47. Across the Universe: Being Asked the Right Questions
  48. Across the Universe: Recognizing the Star
  49. Across the Universe: Heavenly Visitors
  50. Across the Universe: Christmas Presence
  51. Across the Universe: When Reason Itself Becomes Flesh
  52. Across the Universe: Spinning our Hopes
  53. Across the Universe: Relish the Red Planet
  54. Across the Universe: Obedience
  55. Across the Universe: Traveling Light
  56. Across the Universe: The Still Voice in the Chaos
  57. Across the Universe: Europa
  58. Across the Universe: Defamiliarization
  59. Across the Universe: Forbidden Transitions
  60. Across the Universe: Genre and Truth
  61. Across the Universe: False Economies
  62. Across the Universe: Reflections on a Mirror
  63. Across the Universe: Japan
  64. From the Tablet: Why is Easter So Early This Year?
  65. Across the Universe: Oops!
  66. Across the Universe: Dramatic Science
  67. Across the Universe: Me and My Shadows
  68. Across the Universe: Touch the Sky
  69. Across the Universe: Treasure from Heaven
  70. Across the Universe: Gift of Tongues
  71. Across the Universe: Maverick Genius
  72. Across the Universe: Awareness
  73. Across the Universe: Friends in high places
  74. Across the Universe: A Moving Experience
  75. Across the Universe: Grain of truth
  76. Across the Universe: Clerical Work
  77. Across the Universe: Teaching new stars
  78. Across the Universe: Science for the Masses
  79. Across the Universe: Changelings
  80. Across the Universe: Three Lunatic Answers
  81. Across the Universe: Dawn of My Belief
  82. Across the Universe: Martian Sunrise
  83. Across the Universe: Under the Southern Cross
  84. Across the Universe: Clouds from Both Sides
  85. Across the Universe: The Year (2011) in Astronomy
  86. Across the Universe: Jabberwocky and the Curious Cat
  87. Across the Universe: Waiting for the Call
  88. From the Tablet: God is dead; long live the eternal God
  89. Across the Universe: Taking the Heat
  90. Across the Universe: Stellar Round Up
  91. Across the Universe: A Damp Kaboom
  92. Across the Universe: Featureless Features
  93. Across the Universe: Confronting Fear and Terror
  94. Across the Universe: Eye Candy
  95. Across the Universe: The New Paganism
  96. Across the Universe: Immigrant Stars
  97. Across the Universe: Heavenly Visitors
  98. Across the Universe: Christmas Presence
  99. Across the Universe: When reason itself becomes flesh
  100. Across the Universe: Recognizing the Star
  101. Across the Universe: Awaiting the stars
  102. Across the Universe: Tides in our affairs
  103. Across the Universe: A Piece of the Action
  104. Across the Universe: Forced Perspective
  105. Across the Universe: Touched by Heaven
  106. Across the Universe: View from afar
  107. Across the Universe: What good is God?
  108. Across the Universe: Global warning
  109. From The Tablet: Precisely Strange
  110. Across the Universe: Faith and Expectations
  111. Across the Universe: The Boundaries of the Unknown
  112. Across the Universe: Happy Birthday to Us

View the entire series

An Urgent Plea: Pray for Peru.

Casa Hogar Juan Pablo II

Originally, I had planned this post to be a light-hearted reflection on stargazing in the southern hemisphere. The parish of which I am Pastor, St. Joseph Parish in Menomonie, Wisconsin, took a ten-day mission trip to our Diocesan Orphanage, Casa Hogar Juan Pablo II, in Lurin, Peru. In light of my past mission trips to Casa, I was already mapping out a post for the The Catholic Astronomer before departure. However, events from the trip forced a change of theme.

One afternoon, I was offering spiritual direction to a Casa staff volunteer. We were sitting outside underneath the shade of a tree when a low flying helicopter caught our attention. It was so low that it sounded like it was going to land on the orphanage grounds. It was blaring a loud siren while slowly hovering over the city of Lurin. We began to wonder what this warning was about? We had heard earlier of flooding in parts of Peru, but since there was no message with the sirens we presumed it was a local policing matter.

Later that day, another volunteer returned with some friends who had gone to see a river about six miles south of the orphanage. The images they described were surreal. Instead of talking about a river cutting through the Peruvian landscape, they shared images of an aggressive body of brown, muddy water that was carrying dead animals (cows and pigs primarily), bamboo, and other materials used in home building by the poor in the mountains of Peru.

The next day, we had a daytrip to Lima. At one point, I stepped away from the group to look at one of the main rivers that ran through the city. It was raging, brown, and full of all kinds of debris. The next day, I was shocked to hear that the pedestrian bridge I had seen the day before had been washed out by flood water. It became clear that the helicopter we had heard was warning us about the "huaicos." (Toward the end of the flood video below, you can see a woman emerge alive from the watery wreckage.)

How did this happen? Peru is experiencing higher precipitation than usual due to El Nino. Fr. Hirsch, the Director of Casa Hogar Juan Pablo II, told me that about a week before we arrived in Peru there was a rain storm of about two inches. Coming from Wisconsin, two inches of rain doesn't sound like anything life threatening. However, when you realize that certain regions of Peru are considered some of the driest on the planet, two inches of rain can create major issues.

Image of the Costal Desert.

Today, I received an urgent plea from those who work at Casa Hogar Juan Pablo II to pray for the victims of the huaicos. Some regions of Peru have now gone over a week without water and electricity. Casa Hogar is taking donation items that groups like ours bring to the orphanage to help those who are impacted by the floods (including tons of powdered milk our Diocese makes with milk from Wisconsin farms). I would ask those who read The Catholic Astronomer to pray today for Peru and, if your heart is so moved, seek out ways to support those devastated by this disaster. May we embrace our common humanity and seek to support those who are in desperate need.

(Addendum: Many have written to me, asking if there are organizations I know of that are assisting with the flooding in Peru. I am sure there are many, but our orphanage is the only one I am connected with. I presume you could also contact Caritas Internationalis and Catholic Relief Services. The links are below.)

Casa Hogar Juan Pablo II Emergency Assistance to Flood Victims

Caritas Internationalis

Catholic Relief Services

Strange Tales of Galileo and Proving: Omitted Data and the Tides

Last week I wrote a post on how even books for children and travel books state (incorrectly) that Galileo proved that the Earth circles the sun, as Copernicus had said it did.  This post tells a strange story about Galileo’s efforts to prove that the Earth circles the sun.

In Galileo’s time, no telescopic observation was likely to prove Earth’s motion.  Before the telescope had even been invented, Tycho Brahe had proposed a geocentric theory in which the planets circled the sun while the sun, moon, and stars circled the Earth.  Brahe’s theory was mathematically and observationally identical to Copernicus’s heliocentric theory insofar as the Earth, sun, moon, and planets were concerned: the “machinery” of both systems was the same, it was just that in Brahe’s the Earth stood still, whereas in Copernicus’s the sun stood still.  Galileo’s telescopic observations proved that Venus circled the sun—but Venus circled the sun in both Brahe’s geocentric theory and in Copernicus’s heliocentric theory.  Technically, observations of the stars could prove one theory over the other, because in Copernicus’s theory Earth moved with respect to the stars, whereas in Brahe’s it did not.  However, Copernicus had specified that the stars were so far away in his theory that the Earth’s motion was nothing by comparison, and so observing the stars would not reveal Earth’s motion.

The Tychonic geocentric (left) and Copernican heliocentric

The Tychonic geocentric (left) and Copernican heliocentric (right) theories.

With astronomical observations being no help, Galileo looked for proof of Earth’s motion in a common Earthly phenomenon: the tides of the ocean.  The level of the ocean rises and falls every day at beaches and harbors on seacoasts everywhere.  Galileo argued that this rising and falling—the tides—was evidence of Earth’s motion.

Consider:  What are the oceans but giant basins filled with water?  What are seacoasts but the edges of those basins?  Now, how do you make water in a basin rise and fall along the edges of the basin?  There is only one way to do this: you make the water rise and fall by moving the entire basin unevenly; that sloshes the water back and forth, causing it to rise and fall at opposite edges of the basin!  Put a basin of water on the floor of your car; then step on the gas, and then the brake, and then the gas, and so on; the water will slosh everywhere.  If, on the other hand, the car just sits (or even moves at a steady speed in a straight line), and you don’t touch the water, that water will just sit in the basin.

Well, said Galileo, in the heliocentric theory the ocean basins move unevenly, going faster and slower and faster again, just like in your car.  In the heliocentric theory the Earth rotates once per day.  The Earth measures 25,000 miles in circumference, and if the Earth rotates then people at the equator travel all the way around the Earth in 24 hours.  Thus the equator, and the people and waters at the equator, moves at 25,000 miles/24 hours = 1000+ mph.  Moreover, in the heliocentric theory, the Earth orbits the sun, and the orbital speed is almost 70,000 mph.  So imagine that the Earth orbits the sun clockwise, and rotates clockwise, as shown below (the blue arrow shows the Earth’s orbital motion; the red arrow shows the Earth’s rotational motion).

At point A on the side of Earth opposite the sun (the midnight point), the 1000 mph of rotational speed is in the same direction as the orbital speed; at point B on the side of the Earth facing the sun (the noon point), the 1000 mph of rotational speed is opposite the orbital speed.  So, A is moving clockwise around the sun at 70,000 + 1,000 = 71,000 mph, and B is moving clockwise at 70,000 - 1,000 = 69,000 mph.  Therefore a person on the equator is hurtling round the sun 2000 mph slower at noon than at midnight!  Therefore, from noon to midnight that person speeds up by 2000 mph,* and from midnight to noon that person slows down by 2000 mph.  And so do the ocean basins!

Voila!—uneven motion.  This uneven motion must slosh the water in the oceans, causing the tides.  All this Galileo described in a January 1616 letter to a Cardinal Allesandro Orsini (put your usual image of a Roman Catholic Cardinal out of your mind—Orsini was born in 1593; he wasn’t 25 years old at the time).

There seemed to be one problem with all this:  If this uneven motion was the cause of the tides, then the oceans should slosh toward one direction on account of the noon-to-midnight speed-up, and toward the other direction on account of the midnight-to-noon slowdown.  There should be one “up slosh”, or high tide, and one “down slosh”, or low tide, each day.  Thus there should be twenty-four hours between one high tide and the next, and twelve hours between high and low tides.  But in the Mediterranean Sea there are two high tides and two low tides each day, and therefore six hours between high and low tides.

Galileo said that, actually, this was not a problem.  The six-hour period is the result of a secondary effect, he said, namely the water rebounding off the eastern and western ends of the Mediterranean Sea, and the “slosh” being sent back across that sea.  In other words, while the Earth’s heliocentric uneven motion drives the tides, the Mediterranean’s six-hour period is an effect of the length of the Mediterranean.  In the larger Atlantic Ocean, Galileo said, the tide period is twelve hours.  Here are his words on the matter:

[T]he approximately six-hour period commonly observed is no more natural or significant than any other; rather, it is the one which has been observed and described more than others, since it takes place in the Mediterranean Sea around which all our ancient writers and a large part of the moderns have lived.  The length of this Mediterranean basin is the secondary cause that gives its oscillations a six-hour period; whereas on the eastern shores of the Atlantic Ocean, which extends to the West Indies, the oscillations have a period of about twelve hours, as one observes daily in Lisbon, located on the far side of Spain; now, this sea, which extends toward the Americas as far as the Gulf of Mexico, is twice as long as the stretch of the Mediterranean from the Strait of Gibraltar to the shores of Syria, that is, 120 degrees for the former and 56 degrees for the latter, approximately.  Thus, to believe that tidal periods are six hours is a deceptive opinion and it has lead writers to make up many fictional stories. [He then goes on to discuss how complex the tides get within portions of the Mediterranean.]

If you have any familiarity with Atlantic Ocean tides, O Reader, you immediately recognized the “strange” part of this tale.  The business about an Atlantic Ocean twelve-hour period between tides is bogus.  The period is six hours in the Atlantic.

Somewhere along the line Galileo learned he was wrong about the Atlantic tides.  The historical record shows that at least by 1619 he was told of this, as one Tobie Matthew reported as much in a letter to Francis Bacon.  And Galileo, in his 1632 Dialogue Concerning the Two Chief World Systems—Ptolemaic and Copernican (sixteen years after his letter to Cardinal Orsini), omits all mention of the Atlantic, and still sticks with the idea that the six-hour tide period is a characteristic of the Mediterranean.  What Galileo says in the Dialogue is—

Six hours, then, is not a more proper or natural period for these reciprocations than any other interval of time, though perhaps it has been the one most generally observed because it is that of our Mediterranean, which has been the only place practicable for making observations over many centuries. [He then again goes on to discuss how complex the tides get within portions of the Mediterranean.]

So much for Lisbon, the 120 degrees and the 56 degrees, and all that.  From a scientific perspective, this seriously un-cool.  When I am teaching my students how to perform physics experiments, I always emphasize that one cannot selectively choose one’s data.  If you are measuring the acceleration due to gravity by timing the fall of a ball, and not all of your times are in agreement, you cannot just ignore the ones you don’t like.  You have to report all the data you have, both the data you like and the data you don’t like.  You can then try to explain away the data you don’t like, if you think you have good reason to do so, but you cannot just leave it out.

And in the end, leaving out the Atlantic Ocean did not make the problem of the tides period go away.  Consider, for example, the Church officials who investigated the Dialogue (the Dialogue is the book that Galileo was put on trial for) after it was published.  After describing Galileo's tides theory one official wrote:

However, he does not untangle the difficulty that, given this doctrine, since the change between greatest acceleration and maximum retardation of the earth’s motion occurs at twelve-hour intervals, then high and low tides should also occur at twelve-hour intervals. But experience teaches that they occur every six hours.

In science, it never pays to leave out the data.  It was strange, and un-cool, that Galileo did that while trying to prove that the Earth moves.

*You would not feel a gain of 2000 mph in 12 hours.  That’s 2000/12 = 167 mph in an hour, or a little over 80 mph in 30 minutes. Even a fairly sluggish automobile can easily accelerate to 80 mph in well under one minute.

P.S. We now understand the tides to be a result of the gravity of the sun and the moon, not of the Earth’s motion.



The Most Recent Chapter on the Hubble Constant

Astronomers agree that the universe is expanding in all directions, a notion now called the "Hubble expansion" to refer discoverer Mr. Edwin Hubble.

A useful analogy to understand the Hubble expansion is to draw dots onto a balloon to represent galaxies in the universe. As you blow up the balloon the dots expand away from each other. While there seems to be no way around a universal Hubble expansion, now there is controversy brewing regarding the exact value for this rate of expansion. What is at stake may be a tiny misunderstanding in how we make the measurements, or may be a signal of new physics.

Oh, we all agree now on the approximate answer, that the space between galaxies grows such that for every 3.3 million light years a galaxy moves in distance away from us, the velocity of that distant galaxy becomes 70 km/s faster. Equivalently, in astronomer’s jargon we say that the rate of expansion (H0) equals 70 km/s/Mpc, with the symbol H0 used again to recognize the work of Mr. Hubble.

Although this law was first established in 1929, astronomers are still working on getting its exact value nearly 100 years later. To recap the 21st century part of the story, in 2015 one research group measured H0 by studying distant exploding stars, or supernovae. This group, led by Nobel Laureate Dr. Adam Reiss, reported a value for H0 from their high quality data set in the range of 71.2 - 74.8 km/s/Mpc.

Somewhat surprisingly, a different group working with also with high quality data this time from the space satellite “Planck” compute a value for H0 of 67 km/s/Mpc with quoted error bars that make it incompatible with the supernova-based measurement.

This mismatch of the value for H0 between the two groups may sound a bit like scientists being nitpicky. Afterall, we could very well find out later that one or more of the measurements that went into the computations mentioned above have larger uncertainties than originally projected. Then again, if the numbers do hold, then this could be a gentle but persistent beacon that queues us into new physics.

Eratosthenes Drawing Drama plus an Experiment opportunity for schools all over the planet


April 25th 2007 21:30UT - 22:55UT Lunation 8.47 Days Illumination 66.6% 200mm/8mmTVP/ F6/152X Seeing 1 - 2 300gm Daler Paper/Soft Pastels/ Conte Crayon/ Quiling tool/fingers South is up.

On that cold evening back in 2007 Eratosthenes looked powerful in its position emerging into the suns warm rays. Rupes Recta was also inviting and Plato almost called me again. Even drenched in sunlight Plato’s steel grey floor carried those unmistakable flame shaped shadows. Eratosthenes is a truly dramatic crater, a sweeping mountain chain whips away from it in a visual series, of broken, deep shadows. Montes Appeninus is cut and chopped first by Mons Wolf, and then by Mons Ampere.

Next in line, Christian Huygens name is lent to Mons Huygens named in honour of the discoverer of Saturn's largest moon Titan . This high mountain (164,000ft) is a billion miles away from those primal methane or ethane seas discovered by the Cassini Huygens mission on one of its routine flybys.

Mons Bradley and Mons Hadley cradle the Apollo 15 lunar landing area from 1971. A mission that put wheels on the moon for the first time. This wonderfully complex mountain highland system is a challenge to sketch.

Sinus Aestuum (Bay of Billows) appeared to have some ray’s barely visible on the undulating floor of the bay. These are most likely issued from Copernicus hiding in the dark night.

I attempted to sketch the seemingly different heights on the southern edge of this bay; differing grey tones gave up ethereal views which never quite came into focus. The elusive rays appeared to hug the lunar surface rising and falling with the land.

The black edge guided my hand to sketch the neat Timocharis and the lunar surface markings visible now to my eye. I was using a lovely jet black Mungyo soft pastel. Just a little pressure on it caused the whole stick to shatter into a million bits and they went all over the drawing like shrapnel exploding everywhere wow!! gently does it with those sticks, nice black though. The corners of these rectangular sticks make clear defined shapes , the black is a perfect black for use directly or on fingers when blending surface areas.

These days I make an effort to bring key craters like Eratosthenes to the attention of children who attend my workshops. It's good to give moon features context in relation to the historical importance of lunar nomenclature. You can also get really into the spirit of Eratosthenes by taking part in the Eratosthenes Experiment . This is an effort to reproduce his very clever experiment to measure the circumference of the Earth. This year it takes place on March 21st 2017 so you have a short time to get involved but there is a link for doing it on another date and of course there is always next year . You can read all about Eratosthenes the man and his experiment here - You can also register to take part -


Across the Universe: Spotting Ceres

This column first ran in The Tablet in March 2015

Ceres was the first body found in the region between Mars and Jupiter now called the Asteroid Belt. In the late 1700s Titius and Bode had noted a pattern in planet positions that suggested there should be a planet in the gap between Mars and Jupiter; on New Year’s Day of 1801, Father Giuseppi Piazzi found Ceres from his observatory in Sicily.

Bode's Law appears in the footnote on page 635 of his book of astronomy, Anleitung zur Kenntniss des gestirnten Himmels ("Manual for Knowing the Starry Sky") as seen in the Vatican Observatory copy here.

They expected a planet, so that’s what they called Ceres – though William Herschel, who had just discovered the gas giant Uranus, sniffed that such a tiny dot of light was neither planet nor star (Latin, “aster”) but a mere “asteroid.” Only fifty years later, when a number of other such small bodies had been found, did Ceres and the other asteroids get “demoted” to the status of “minor planet.” (And later work showed that the Titius-Bode pattern which predicted a planet at Ceres’ position was actually just a coincidence of numbers, not a reliable law.)

A mere 950 km in diameter, Ceres is indeed small – even Pluto’s diameter is two and a half times bigger and more than 15 times its volume – but it’s still by far the biggest object in the asteroid belt. It’s nearly twice the diameter and six times the volume of Vesta. We can measure its gravity’s tiny pull on Mars to estimate its mass, and we can just make it out as a disk in our biggest telescopes to get its diameter and volume, so we know it has a density somewhere between water and rock. We also know that, for its size, it reflects little light; its surface must be almost jet black, like a dark meteorite.

Indeed, this small size and dim surface made Ceres seem for many years a dull subject for study. But in 2006, when Pluto and other similarly-sized objects out beyond Neptune were recognized as a separate family of bodies called Dwarf Planets, it seemed reasonable to add Ceres to their number. So once again Ceres was re-classified. (Unlike Pluto, Ceres doesn’t have a vocal fan club so its repeated reclassifications have gone mostly unnoticed by the general public.)

A few years ago the Hubble telescope observed Ceres’ blurry disk to be slightly flattened. With a little fancy math (and some assumptions) you can compare the flattening with the spin rate to conclude that, unlike rubble-pile asteroids, Ceres was a solid body compressed by its own gravity, with a dense core. That implied its upper regions were full of low density stuff, probably ice, below a dust-covered surface. This idea gained traction when Esa’s Heschel Space Telescope, looking for water in our galaxy, stumbled on a detection of a plume of water from Ceres itself.

Dawn, approaching Ceres earlier this year, added the final touch: the discovery of two small white spots that many scientists are suggesting might be bits of ice poking through its dusty crust. Now we’re speculating that this fresh ice may indicate liquid water – and life? – inside this body, once thought so dull and uninteresting.

Occator Crater, measuring 57 miles (92 kilometers) across and 2.5 miles (4 kilometers) deep, contains the brightest area on Ceres. 
Dawn's close-up view reveals a dome in a smooth-walled pit in the bright center of the crater. A separate figure shows the bright spots in a mosaic of two Dawn images taken using a shorter exposure time to show details within the bright features that are overexposed, or nearly so, in the full mosaic. The images used to make these mosaics were taken from Dawn's low-altitude mapping orbit (LAMO), 240 miles (385 kilometers) above Ceres. Credit: NASA


But we’ve only just arrived; it is far too early to jump to conclusions. Planet or asteroid or dwarf? Black meteorite, dusty ice ball, or a home for life? If we’ve learned any lesson from Ceres, it’s to take in what it shows you with an open mind, rather than assume you know it all ahead of time, and only see what you expect to see.

That would be like worrying over the empty Tomb, without noticing the Gardener standing beside you.

(Most recently, organic material has been found on the surface of Ceres; for the latest Ceres information, check out the Dawn website.)

Punished for Proving

galileobooks1History of astronomy turns up in unexpected places.  Unfortunately that history is often poorly presented.  Consider this example, found in a children’s book called C is for Ciao: An Italy Alphabet by Elissa D. Grodin and Governor Mario Cuomo:

G is for Galileo,
punished when he proved
that the sun was sitting still
and the earth’s the one that moved

On the same page is—

Until the Polish astronomer Nicolas Copernicus discovered that the sun is the center of our solar system... people since the second century had thought the sun revolved around the earth.

Click on this image to enlarge.

Click on this image to enlarge.


In developing the telescope, Galileo was able to prove that Copernicus’s theory was correct.  This caused a problem with church leaders of the day, who—disrespectful of scientific facts—were offended by the idea that the earth was not the center of the solar system.

But Copernicus did not discover that the sun is the center—he hypothesized that it was.  Galileo did not prove that the earth moves.  He proved that certain older ideas about the universe were wrong (although some astronomers in Galileo’s time might have argued even this point).

Consider the wonderful illustration of Galileo in C is for Ciao.  Look behind Galileo.  That is not the heliocentric hypothesis of Copernicus that is shown.  It is the hypothesis of Tycho Brahe, a very new hypothesis in Galileo’s time, in which the sun and moon and stars circled the Earth, while the planets circled the sun.  See at upper right where it says “Circulus Jovis” (“The Circle of Jupiter”) and shows Jupiter with four moons (moons discovered by Galileo)?  Note that the Jovian circle is centered on the sun (the sun being behind Galileo’s right temple).  Meanwhile the sun is circling something else: the stationary Earth (behind Galileo’s throat). galileobooks3

Galileo did not support Brahe’s hypothesis, and probably would not be happy to see himself portrayed in front of it.  However, it was wholly compatible with Galileo’s telescopic discoveries.  It was why, for example, using the telescope to prove that Venus circled the sun was not the same as proving that Earth moves—because in Brahe’s system Venus circled the sun, and the Earth did not move.  (Proving Earth’s movement—showing that Copernicus was right and Brahe wrong—took a very long time.  I can recommend a book on this topic if you want all the details.)

The illustration behind Galileo is from the Harmonia Macrocosmica of Andreas Cellarius, as seen here. The left-hand figure is Macrocosmica's illustration of the Tychonic system. The right-hand figure is Macrocosmica's illustration of the Copernican system (the one Galileo supported).

The illustration behind Galileo is from the Harmonia Macrocosmica of Andreas Cellarius, as seen here. The left-hand figure is Macrocosmica's illustration of the Tychonic system. The right-hand figure is Macrocosmica's illustration of the Copernican system (the one Galileo supported).

So C is for Ciao is wrong about some things.  It should indeed celebrate Galileo’s accomplishments, but it should correctly present the business about proofs and people disrespecting facts, and it should put the correct picture behind Galileo.  But C is for Ciao is not alone.  Consider DK Eyewitness Travel: Italy 2016.  It says—

Galileo Galilei proved that the earth revolved around the sun, overturning Church doctrine.  He was convicted of heresy in 1633.  Here he shows the rings of Saturn to Venetian senators.

galileobooks4There’s “proved” again.  And Galileo could hardly see the rings of Saturn with his telescope, and he did not recognize them as being rings.  Viewing Saturn through his telescopes was very difficult.  I doubt he showed such a difficult object to non-astronomers.

But one can’t be too hard on C is for Ciao and Italy 2016.  After all, look at the edition of Galileo’s Dialogue that is currently available.  What is on its back cover?  “Galileo proved.”galileobooks5

Why do so many people view science as being about smart men proving plain truths and having to drag everyone else into the light of scientific facts (and getting punished for that).  Why do they not view it as being about a dynamic contest of ideas that are compatible with the facts (like Tycho vs. Copernicus)?  Perhaps because their views are formed by the books they read as children, or even by travel books.  Such books might be the only science history many people read.  It is important that the people who write these books do their research and not be disrespectful of historical facts.


Should you (or someone you love) go to MIT?

Today is “PI” day (written in American style, 3/14…) and MIT is holding a one day fundraiser… In honor of this day, this provides me with an excuse to post something I wrote for my Live Journal account a few years ago and which I get asked about from parents (and grandparents) of prospective students all the time. Of course the MIT I attended was nearly half a century back, but things haven’t changed all that much… Do I recommend MIT? Only if you are a very particular type of student. There is a reason why schools like MIT are so rare: because for most people, it is the wrong school to go to. MIT is not a place to find yourself. Because it is such an intense environment, it can be devastating to anyone who doesn’t already have a strong sense of who they are, and where they want to go. (Mind you, after MIT is finished with you, the person … Continue reading

Learning from a Flashlight in the Sky

While many of us are dazzled by the spectacular examples of galaxies each one with its own 10-100 billion stars, some of us choose instead to study the regions between the galaxies. There is a fair amount of hydrogen gas in this “intergalactic medium,” yet this gas typically is too faint to see directly in images. We are able to study this dim gas only by looking at how it affects the light coming from bright objects in the background called quasars. There are a great many bright quasars, or galaxies with extremely bright nuclei, in the universe. These quasars each produce a tremendous amount of light much like the welcome sight of a flashlight on an otherwise dark and deserted hiking trail. Indeed if you were to look at the flashlight of a distant hiker during an evening walk, you may see the flashlight seem to ‘flicker’ not because the battery was running out but rather as a result … Continue reading

Across the Universe: The Boundaries of the Unknown

This column first ran in The Tablet in March 2014 Isaac Newton thought that planetary orbits in our solar system were kept stable by God’s direct intervention; they were proof to him that God existed. A hundred years later, the great French mathematician and skeptic Pierre-Simon Laplace described his new orbital theory to Napoleon and supposedly quipped of God’s role, “I have no need for that hypothesis.” In fact, it is bad theology to reduce God to merely a gap-filling hypothesis. Only recently, however, have we learned that, actually, planetary motions may sometimes not be so stable after all. One of the pioneers of studying chaos theory in celestial dynamics is Jack Wisdom, an MIT professor (and MacArthur “genius”) who is visiting the Vatican Observatory this month. He’s working now on modeling the complex interaction between the Moon’s orbit and spin with the spin and orbit of the Earth. It’s all tied to the larger issue of the origin of … Continue reading

Copernicus’s On the Revolutions—A Book That Continues to Challenge

Last week’s post featured old science books from the William Marshall Bullitt Collection in the Archives and Special Collections (ASC) of the Ekstrom Library of the University of Louisville here in Kentucky, and readers of this blog may recall an earlier post about the collection, too.  I currently have the enjoyable task of studying the books in the collection and writing discussions of them for the ASC—discussions specifically intended for a diverse audience that might include scholars, students at varying levels, and interested members of the general public.  One of the books in the collection that no doubt would interest readers of this blog (and that readers can go to see and study at the University of Louisville) is Nicolas Copernicus’s 1543 De Revolutionibus Orbium Cœlestium, or On the Revolutions of Heavenly Spheres.  This post is an adaptation (with permission) of the discussion I wrote for the ASC. De Revolutionibus is a book that challenged scientists and non-scientists alike when it … Continue reading

Grand Finale – Painting inspired by the Cassini Mission to Saturn

Also in Exploring the Solar System Exploring the Solar System: The Mass of the Sun Marvellous Mars Drawing Workshop at Dunsink Observatory Dublin Astronomical Sketching – Education in action Stars Wonderful Stars at Wexford Town Library Ireland Get ready the Perseids are coming Space the final Frontier – World Space Week 2016 On the richness of the lunar surface Dark Sky Magic at Ballycroy National Park Mayo Ireland Grand Finale – Painting inspired by the Cassini Mission to Saturn View the entire series … Continue reading