There are millions of pieces of rocky material left over from the formation of our solar system. These rocky chunks are called asteroids, and they can be found orbiting our Sun. Most asteroids are found between the orbits of Mars and Jupiter. They orbit the Sun in a doughnut-shaped region of space called the asteroid belt.
The Main Asteroid Belt. Colors: green are main belt asteroids, yellow are asteroids that cross the orbit of Mars, red are asteroids that cross the orbit of Earth. Credit: Scott Manley
Asteroids come in many different sizes—from tiny rocks to giant boulders. Some can even be hundreds of miles across! Asteroids are mostly rocky, but some also have metals inside, such as iron and nickel. Almost all asteroids have irregular shapes. However, very large asteroids can have a rounder shape.
The asteroid belt is about as wide as the distance between Earth and the Sun. It’s a big space, so the objects in the asteroid belt aren’t very close together. That means there is plenty of room for spacecraft to safely pass through the belt. In fact, NASA has already sent several spacecraft through the asteroid belt!
Caption: Enhanced color view of dwarf planet Ceres captured by the Dawn spacecraft. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
The total mass of objects in the asteroid belt is only about 4 percent the mass of our Moon. Half of this mass is from the four largest objects in the belt. These objects are named Ceres, Vesta, Pallas and Hygiea.
The dwarf planet Ceres is the largest object in the asteroid belt. However, Ceres is still pretty small. It is only about 587 miles across—only a quarter the diameter of Earth’s moon. In 2015, NASA's Dawn mission mapped the surface of Ceres. From Dawn, we learned that the outermost layer of Ceres—called the crust—is made up of a mixture of rock and ice.
The Dawn spacecraft also visited the asteroid Vesta. Vesta is the second largest object in the asteroid belt. It is 329 miles across, and it is the brightest asteroid in the sky. Vesta is covered with light and dark patches, and lava once flowed on its surface.
The asteroid belt is filled with objects from the dawn of our solar system. Asteroids represent the building blocks of planets and moons, and studying them helps us learn about the early solar system.
Seventeen years ago, astronomers witnessed a supernova go off 40 million light-years away in the galaxy called NGC 7424, located in the southern constellation Grus, the Crane. Now, in the fading afterglow of that explosion, NASA's Hubble Space Telescope has captured the first image of a surviving companion to a supernova. This picture is the most compelling evidence that some supernovas originate in double-star systems.
“We know that the majority of massive stars are in binary pairs,” said Stuart Ryder from the Australian Astronomical Observatory (AAO) in Sydney, Australia, and lead author of the study. “Many of these binary pairs will interact and transfer gas from one star to the other when their orbits bring them close together.”
Seventeen years ago, astronomers witnessed supernova 2001ig go off 40 million light-years away in the galaxy NGC 7424, in the southern constellation Grus, the Crane. Shortly after, scientists photographed the supernova with the European Southern Observatory’s Very Large Telescope (VLT) in 2002. Two years later, they followed up with the Gemini South Observatory, which hinted at the presence of a surviving binary companion. As the supernova’s glow faded, scientists focused Hubble on that location in 2016. They pinpointed and photographed the surviving companion, which was possible only due to Hubble’s exquisite resolution and ultraviolet sensitivity. Hubble observations of SN 2001ig provide the best evidence yet that some supernovas originate in double-star systems. Credits: NASA, ESA, S. Ryder (Australian Astronomical Observatory), and O. Fox (STScI)
The companion to the supernova’s progenitor star was no innocent bystander to the explosion. It siphoned off almost all of the hydrogen from the doomed star’s stellar envelope, the region that transports energy from the star’s core to its atmosphere. Millions of years before the primary star went supernova, the companion’s thievery created an instability in the primary star, causing it to episodically blow off a cocoon and shells of hydrogen gas before the catastrophe.
Evolution of Type IIb Stripped-Envelope Supernova. Credits: NASA, ESA, and A. Feild (STScI)
The supernova, called SN 2001ig, is categorized as a Type IIb stripped-envelope supernova. This type of supernova is unusual because most, but not all, of the hydrogen is gone prior to the explosion. This type of exploding star was first identified in 1987 by team member Alex Filippenko of the University of California, Berkeley.
How stripped-envelope supernovas lose that outer envelope is not entirely clear. They were originally thought to come from single stars with very fast winds that pushed off the outer envelopes. The problem was that when astronomers started looking for the primary stars from which supernovas were spawned, they couldn’t find them for many stripped-envelope supernovas.
“That was especially bizarre, because astronomers expected that they would be the most massive and the brightest progenitor stars,” explained team member Ori Fox of the Space Telescope Science Institute in Baltimore. “Also, the sheer number of stripped-envelope supernovas is greater than predicted.” That fact led scientists to theorize that many of the primary stars were in lower-mass binary systems, and they set out to prove it.
Looking for a binary companion after a supernova explosion is no easy task. First, it has to be at a relatively close distance to Earth for Hubble to see such a faint star. SN 2001ig and its companion are about at that limit. Within that distance range, not many supernovas go off. Even more importantly, astronomers have to know the exact position through very precise measurements.
VLT's four Unit Telescopes, Credit: ESO/H.H.Heyer
In 2002, shortly after SN 2001ig exploded, scientists pinpointed the precise location of the supernova with the European Southern Observatory’s Very Large Telescope (VLT) in Cerro Paranal, Chile. In 2004, they then followed up with the Gemini South Observatory in Cerro Pachón, Chile. This observation first hinted at the presence of a surviving binary companion.
Knowing the exact coordinates, Ryder and his team were able to focus Hubble on that location 12 years later, as the supernova’s glow faded. With Hubble’s exquisite resolution and ultraviolet capability, they were able to find and photograph the surviving companion—something only Hubble could do.
Prior to the supernova explosion, the orbit of the two stars around each other took about a year.
When the primary star exploded, it had far less impact on the surviving companion than might be thought. Imagine an avocado pit—representing the dense core of the companion star—embedded in a gelatin dessert—representing the star’s gaseous envelope. As a shock wave passes through, the gelatin might temporarily stretch and wobble, but the avocado pit would remain intact.
In 2014, Fox and his team used Hubble to detect the companion of another Type IIb supernova, SN 1993J. However, they captured a spectrum, not an image. The case of SN 2001ig is the first time a surviving companion has been photographed. “We were finally able to catch the stellar thief, confirming our suspicions that one had to be there,” said Filippenko.
Perhaps as many as half of all stripped-envelope supernovas have companions—the other half lose their outer envelopes via stellar winds. Ryder and his team have the ultimate goal of precisely determining how many supernovas with stripped envelopes have companions.
Their next endeavor is to look at completely stripped-envelope supernovas, as opposed to SN 2001ig and SN 1993J, which were only about 90 percent stripped. These completely stripped-envelope supernovas don’t have much shock interaction with gas in the surrounding stellar environment, since their outer envelopes were lost long before the explosion. Without shock interaction, they fade much faster. This means that the team will only have to wait two or three years to look for surviving companions.
The paper on this team’s current work was published on March 28, 2018, in the Astrophysical Journal.
The Hubble Space Telescope in orbit. Credit: NASA/JPL-Caltech.
The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington, D.C.
The British fantasy writer Neil Gaiman tells the story of attending a gathering of great writers, scholars, and thinkers, and wondering if he really belonged in that group. Next to him, another attendee also named Neil voiced similar doubts. “I just look at all these people, and I think, what the heck am I doing here? They’ve made amazing things. I just went where I was sent.” To which Gaiman replied, “Yes. But you were the first man on the Moon. I think that counts for something.”
The 2017 Annual Report featured the meeting of Nobel laureate Gerald t' Hooft with Pope Francis, introduced by Specola cosmologist Fr. Gabriele Gionti.
In that spirit, in May 2017 I presented to Pope Francis the attendees of our workshop on Black Holes, Gravitational Waves, and Space-time Singularities. The scientists included 35 of the brightest in the field, including a Nobel laureate. Two of them gave the Pope a copy of their work announcing the discovery of gravitational waves. (I gave the Pope a book written by children at my old elementary school.)
A major theme of the workshop was the exchange of information. Would information survive passage into a black hole, or would every kind of ordering be erased in that space-time singularity? The question has implications also for the singularity at the beginning of the Big Bang. What sort of theory would allow one to even answer that question? Will we ever have a workable theory of quantum gravity, to combine the insights of Einstein’s General Relativity (which works fine at astronomical scales) with the quantum physics that seems to operate at the tiniest scales?
What was wonderful to me was seeing how the setting of this workshop at the Vatican provided just the opposite of a black hole: rather than destroying information, the feeling of “neutral ground” here fed discussions that went on long after the formal sessions had ended… into the meals the attendees shared together, the walk through the Papal Gardens, even on the bus ride to the Papal Audience.
Conversation, the transmission of information, is the heart of science. Things can also get mis-transmitted, of course. Most of the news coverage (including in The Tablet) called our meeting a “faith and science” workshop even though the only faith expressed at the meeting was faith in, or against, the standard models of cosmology. (“I really hope there’s a multiverse,” one attendee confessed to me.)
And we got the usual spate of emails and tweets from those who have grand ideas about cosmology, if only the rest of the world would listen. What makes the 35 folks at our workshop worth listening to on this topic more than all the helpful enthusiasts who email us? The experts and prize winners have paid their dues: a lifetime of learning the real meaning of the words “singularity” and “space-time” in a way that journalists (or columnists like me) can only hint at; a lifetime of not only talking, but also listening. (One attendee was notorious for talking over those who disagreed with him; the rest of the group eventually just ignored him.)
That’s one difference between the real scientists and the wanna-be’s. The email writers are sure they are right; we know we aren’t, completely, and never will be. And that’s what gives us courage to believe we’re not imposters. Science is not the truth, but the search for truth.
Pope Francis understands that. “I am deeply appreciative of your work,” he told us, “and I encourage you to persevere in your search for truth. For we ought never to fear truth, nor become trapped in our own preconceived ideas, but welcome new scientific discoveries with an attitude of humility.”
[The title I chose for this column comes from something I once heard my grad school buddy Cliff Stoll say: "Data is not information, information is not knowledge, knowledge is not understanding, understanding is not wisdom."]
It is easy to see from this image why people have been drawn to the Nile River in Egypt for thousands of years. Green farmland marks a distinct boundary between the Nile floodplain and the surrounding harsh desert. ~USGSDownload this image from USGS (7801 x 8400 px, 51.9 MB). View all the USGS Earth as Art Galleries: Gallery 1, Gallery 2, Gallery 3, Gallery 4.
Here are some close-ups from the image above:
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Landsat 8 is the eighth satellite of the Landsat program. Launched on Feb. 11, 2013.
Landsat 8 - Earth Observation Satellite. Credit: NASA Eyes on the Solar System / Bob Trembley.
Landsat 8 consists of three key mission and science objectives:
Collect and archive medium resolution (30-meter spatial resolution) multispectral image data affording seasonal coverage of the global landmasses for a period of no less than 5 years;
Ensure that Landsat 8 data are sufficiently consistent with data from the earlier Landsat missions in terms of acquisition geometry, calibration, coverage characteristics, spectral characteristics, output product quality, and data availability to permit studies of landcover and land-use change over time;
Distribute Landsat 8 data products to the general public on a nondiscriminatory basis at no cost to the user.
This entry is part 7 of 7 in the series Guest Column
An Observing Man for all Seasons
On Friday evening, May 4, 2018, the Tucson Amateur Astronomy Association (also known as the TAAA) bestowed its highest honor, the Bart and Priscilla Bok award, to Dr. Tim Hunter, a retired radiologist at the University of Arizona. The award honors a lifetime of service to astronomy, and dedication and a passion for the night sky.
Dr. Tim Hunter, dressed for observing, stands with the original 24-inch telescope at the Grasslands Observatory. Credit: David H. Levy
The TAAA’s Bok award was started around 1984 in honor of the husband-and-wife team of astronomers whose lives were devoted to studying our galaxy, the Milky Way. Bart and Priscilla Bok’s enthusiasm led to four editions of a popular science book called The Milky Way. After Priscilla’s death in 1975, Bart produced a legendary fifth edition, which he dedicated in his wife’s memory. “This is the first time I've revised the book without her,” he wrote.
At that time, Tim Hunter was beginning his career in radiology and rapidly expanding his work in astronomy. He has approached the night sky with an energy that can hardly be compared to anyone’s. He has taken thousands of photographs, ranging from five planets in a single exposure back in 1984 to in-depth images of remote galaxies from his Grasslands Observatory in the hills around Sonoita, in southeastern Arizona.
Besides observing, Tim has maintained a close relationship with the TAAA. He served as its president during the early 1990s, the time when the association was just beginning ITS search for a dark sky observing site that has evolved today as the Chiricahua Astronomy Complex. Tim has written an astronomy column for the Arizona Daily Star, Tucson’s newspaper, for years and years. Through this writing Tim uses his considerable talent to inspire his readers to enjoy the night sky. Just as he operates one of his remote telescopes in Sonoita from his Tucson home, he hopes that his readers will enjoy the sky from their homes, either just by looking up or by using their small telescopes.
Of all the many different lectures Tim has given over decades, by far my favorite is his autobiographical “My Life and Hard Times as an Amateur Astronomer.” I first heard him give this lecture in 1990. I sat in the front row. I smiled. I laughed. I cried. I was taken by the depth and perception of Tim’s words and insights. Here is a man who loves the night sky. It is with this spirit and pleasure that, with much happiness, we present Tim Hunter with his Bart and Priscilla Bok award.
The June 8, 2004 Transit of Venus. Credit: Dr. Tim Hunter.
Black holes are hard to point to because they are...black.
Nevertheless, we did find out that there is a supermassive black hole at the Milky Way's center. It has a mass that is greater than that of the Sun by factors of tens of millions.
We arrived at this conclusion by watching what individual stars do that are very near to the Galactic center. These ill-fated stars describe oval-shaped orbits as if they are waltzing about some invisible central object.
Recent studies using sophisticated computer simulations are showing that about ten supermassive black holes should be lurking somewhere in galaxies the size of the Milky Way. Only one of these monsters would be situated at the very center (the one we found), while the others would orbit the galaxy at distances that are large compared to the Sun's distance from the Galactic center (whew), and far above or below the Galactic plane.
Fortunately, we are situated exactly in the plane in a relatively dull and unregarded ``suburb" of a spiral arm.
So do we have a chance to detect these other supermassive black holes in the Milky Way, if they exist? Black holes are impossible to see directly unless they are actively consuming some other object.
One idea that comes to mind is that we can discover black holes indirectly, by watching the effect they have on the light coming from the objects that happen to be behind them.
Black holes, afterall, are just like all other massive objects in that they the bend light around them. Shining a light near a black hole (but not into the black hole) will have the curious effect that the light appears to emerge from the other side. As an analogy, it is as if when you shine a flashlight onto a friend, that light would bend around your friend's body and appear to emerge from other side!
By monitoring millions of stars about once per week for evidence of this "light bending" effect, one can in principle locate these giant objects. To date no one has
found another supermassive black hole in our Galaxy. The best observatory to begin a search for such hidden
monsters is probably the Large Synoptic Sky Telescope (LSST) which is currently under construction in Chile.
The Moon, Mars and Saturn are spread across the southern sky before dawn.
Southern sky at 5:00 AM, May 8, 2018. Credit: Stellarium / Bob Trembley.
The Moon is high in the southern sky during the morning, and sets in the southwest shortly before 1:00 PM
Southern sky at 7:00 AM, May 8, 2018. Credit: Stellarium / Bob Trembley.
Close-up of the Moon in the southern sky at 9:00 AM, May 8, 2018. Credit: Stellarium / Bob Trembley.
Venus continues to play the role of the "evening star"- low in the western sky near sunset.
Western sky at 9:00 PM, May 8, 2018. Credit: Stellarium / Bob Trembley.
Jupiter, at opposition this week, will be bright in the southern sky and visible all evening.
Southern sky at midnight, May 9, 2018. Credit: Stellarium / Bob Trembley.
Cygnus, Lyra and Hercules are low in the eastern sky at midnight.
Eastern sky at midnight, May 9, 2018. Credit: Stellarium / Bob Trembley.
The Moon
The Moon visible in the morning skies as a waning crescent just past third quarter. The Moon rises later each morning, and will look more "crescent-like" over the next few mornings; May 8-10th would be good days to do some early morning sidewalk astronomy at schools!
The Sun
The Sun has a small spot near the equator that is decaying, and another spot rotating into view along the eastern limb. You can try to find the sunspots in this 4K image: [Link]
Coronal holes at both poles with an occasional hole at the equator seems to be "a thing" the last few months... because that's what we've got going on now! You can see the bright areas of coronal activity where the sunspots are. The new sunspot rotating into view is showing a lot of coronal loop activity.
The solar wind speed is 673 km/sec, with a density of 9.0 protons/cm3. Both of those numbers are the largest I've seen them since starting to report them. SpaceWeather.com says: "For the 4th day in a row, a stream of high-speed solar wind is blowing around Earth. The gaseous material is flowing from a wide hole in the sun's atmosphere--so wide that Earth could remain inside the stream for another 2 or 3 days. NOAA forecasters say there is a 50% chance of polar geomagnetic storms on May 8th as the solar wind speed tops 600 km/s (1.3 million mph)."
There have been some impressive prominences in the Sun's chromosphere over the last couple days. The sunspot rotating into view is clearly visible and showing a lot of activity.
You can view the Sun in near real-time, in multiple frequencies here: SDO-The Sun Now.
You can create your own time-lapse movies of the Sun here: AIA/HMI Browse Data.
You can browse all the SDO images of the Sun from 2010 to the present here: Browse SDO archive.
In this diagram of the inner solar system, all of the fireball orbits intersect at a single point--Earth. Source: Spaceweather.com
The Solar System
This is the position of the planets in the solar system:
Position of the planets in the inner solar system, May 8, 2018. Credit: NASA Eyes on the Solar System / Bob Trembley.
Position of the planets in the inner and middle solar system, May 8, 2018. Credit: NASA Eyes on the Solar System / Bob Trembley.
Exoplanets
Confirmed Exoplanets: 3,725 (4/26/2018)
Multi-Planet Systems: 613 (4/26/2018)
Kepler Candidate Exoplanets: 4,496 (8/31/2017)
TESS Candidate Exoplanets: 0 Data from the NASA Exoplanet Archive
Recent Launchs
The Mars InSight mission launched on Saturday May 5th at 7:05 AM.
InSight, short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is a Mars lander designed to give the Red Planet its first thorough checkup since it formed 4.5 billion years ago. It is the first outer space robotic explorer to study in-depth the "inner space" of Mars: its crust, mantle, and core.
Studying Mars' interior structure answers key questions about the early formation of rocky planets in our inner solar system - Mercury, Venus, Earth, and Mars - more than 4 billion years ago, as well as rocky exoplanets. InSight also measures tectonic activity and meteorite impacts on Mars today.
The lander uses cutting edge instruments, to delve deep beneath the surface and seek the fingerprints of the processes that formed the terrestrial planets. It does so by measuring the planet's "vital signs": its "pulse" (seismology), "temperature" (heat flow), and "reflexes" (precision tracking).
This mission is part of NASA's Discovery Program for highly focused science missions that ask critical questions in solar system science. - From the InSight website.
Mars InSight on Approach to Mars, Nov. 26, 2018. Credit: NASA Eyes on the Solar System / Bob Trembley.
This artist's concept depicts the InSight lander on Mars after the lander's robotic arm has deployed a seismometer and a heat probe directly onto the ground. InSight is the first mission dedicated to investigating the deep interior of Mars. The findings will advance understanding of how all rocky planets, including Earth, formed and evolved. Credits: NASA/JPL-Caltech
Apps used for this post:
Stellarium: a free open source planetarium app for PC/MAC/Linux. It's a great tool for planning observing sessions. NASA Eyes on the Solar System: an immersive 3D solar system and space mission simulator - free for the PC /MAC. I maintain the unofficialNASA Eyes Facebook page.
In my previous posts on Science in the Classroom, I've presented resources to you on the themes of Awe and Wonder and the question, What does it means to be human? In both sets of resources, what begins to emerge is that a powerful bridge between faith and science is found when the measurable and quantifiable aspects of creation begin to point to a beauty and elegance that sparks a sense of wonder, evoking an organic ethical vision of protecting the dignity of the human person and all of creation. This relationship between "a world of measurements" and "a world of wonder and dignity" reminds me of St. Bonaventure's classic work, The Mind's Journey to God. Click here to view a video I did for the Vatican Observatory Foundation, explaining this distinction in the thought of St. Bonaventure.
Fr. Stanley Jaki
What begins to emerge from the writings of St. Bonaventure is the idea that faith and science explore fundamentally different types of questions, pointing to the same source of truth. This distinction reminds me of another enlightening classification to help understand the relationship between faith and science that comes from the late Benedictine Priest, Fr. Stanley Jaki. In a lecture I have provided at the end of this post, Fr. Jaki makes the clear distinction that theology measures nothing, while exact science deals with numbers and observation of change. This distinction points to how theology and science explore truth in two very different ways.
On a personal level, these distinctions tease out a principle that I have shared before on what I see as the healthiest approach to faith and science: Let faith be faith and science be science, trusting that, as both fields seek truth, the bridges between faith and science will naturally emerge with time and patience. As with all principles, it is imperfect and needs further refinement, but, as a starting point, I have found it a durable and good avenue into a healthy discussion on faith and science. Here is a second video I did for the Vatican Observatory on how Stanley Jaki would use a story of Lord Kelvin to emphasize the distinction between scientific questions and theological/philosophical questions.
These theological perspectives on the distinction between faith and science are affirmed by a resource that comes from the National Academy of Science. In its open source text on teaching evolution, the Q and A section explores the question faith and science. In the section on religion, it affirms that scientific truth is tentative, often modified, changed, or discarded by new data. Theology explores foundational truths that have been revealed through Natural Reason and Divine Revelation. Therefore, theological exploration is more of a deepening of these fundamental truths in contrast to changing these truths.
Below are a series of videos that deepen this distinction. The first is from the AAAS's Science for Seminaries series, exploring the Working of Science. The second video is from the series of videos Exploring Science in Seminaries, speaking about what scientific literacy needs to look like for clergy in daily ministry. Third, I will present a creative video taking a section from C.S. Lewis' Mere Christianity to examine the virgin birth of Jesus Christ in light of religion and science. The final video is of Fr. Stanley Jaki, speaking about the distinction between the nature of science and the nature of theology (along with a rather lengthy reflection on scientists who steal other scientists ideas - like his own).
A giant nineteenth-century orrery that mechanically reproduces the motions of the inner solar system can be found at the Center for Kentucky History in Frankfort, Kentucky. The orrery—also known as a planetarium—was created to be a teaching tool by Thomas Barlow (1791-1865) of Lexington, Kentucky, with his son Milton. However, it is also a work of astronomical art!
The Barlow Orrery, also known as The Barlow Planetarium. The Barlows built at least 20 of these. Sayre School in Lexington, Kentucky purchased this one from Milton Barlow in the 1880’s for astronomy instruction. More than a century later, in the year 2000, the school donated it to the Kentucky Historical Society.
This image gives a sense of the size of the orrery. The sun is the size of a large beach ball. No doubt this large machine was a fantastic tool for explaining how the solar system functioned and why the seasons occur—much better than computer apps that do the same thing today, but that are confined to a 2-D screen that is much smaller than this 3-D model.
Part of a diagram of the orrery, showing a “side view” of the gear train that makes the orrery work. At the end of the arm that holds the Earth and moon was a handle. This handle was used to pull the Earth-moon system around the large wooden ring that comprises the circumference of the orrery. The pulling action set a gear train in motion. That gear train rotated the Earth, drove the moon to orbit the Earth, caused Earth’s axis to hold a constant angle (so that it would always point toward a “north star”), drove Mercury and Venus to orbit the sun, and caused the sun to rotate, all at the correct rates. The machinery was sufficiently accurate that it could be used to predict or replicate alignments of the planets on given dates.
A close-up of the Sayre School orrery’s gear train.
A “top view” of the gear train. These diagrams are from a French patent that was granted on the orrery.
This machinery causes the Earth to rotate, the moon to orbit, and the axis of the Earth to remain pointed toward the “north star”.
This machinery at the center of the orrery drives the motions of Mercury, Venus, and the Sun.
Around the outer ring are the months and days of the year. Presumably, once the orrery was calibrated, the handle could be set at a certain month and day and the positions of all the bodies of the inner solar system observed.
Representations of various zodiac constellations are also found on the outer ring.
Left—a brochure for the Barlow Planetarium (orrery). Right—illustration of the Barlow device at the Paris Exposition of 1867.
The orrery is said to be accurate enough to show the alignments of the planets on various days. For example, Thomas Barlow is said to have used one of his orreries to predict the evening alignment of the Moon, Venus, and Mercury on Christmas of 1851. The positions of these objects are shown here, as seen from Earth (left) and within the solar system (right). The Sayre School’s Barlow orrery was in need of work when the school donated it to the Kentucky Historical Society, so it may not be sufficiently functional to test it for accuracy.
I actually learned about the Barlow from Jamie Day, a professor of physics at Transylvania University in Lexington. He gave a talk on it at a conference at the University of Notre Dame in July of 2017.* This is the second grand-scale piece of astronomical art in Frankfort, Kentucky that I have featured in the Astronomy in Art and Architecture series (click here for the whole series)—the other being the Kentucky Vietnam Veterans Memorial. Thus Frankfort, Kentucky’s Capital, is definitely worth a visit if you are interested in astronomy.
*The title and abstract of Prof. Day's talk at the University of Notre Dame:
“The History and Conservation of the Barlow Planetarium” Abstract: In the mid-1800s, Thomas Harris Barlow—an agricultural industrialist and mechanical savant—designed an intricate and expansive mechanical model of the inner solar system. Barlow collaborated with James Dodd—mathematician and president of Transylvania University—to calculate the gearing, and labored for over a decade before arriving at his final design: a thirteen-foot diameter mechanism of wood, glass, filigreed cast iron, and precision gears. For nearly fifty years Barlow and his son, Milton, manufactured and marketed the planetarium, which was met with great acclaim. Unfortunately, the enormous stresses inherent in such a large instrument frequently led to mechanical failure. Recently, two examples have been beautiful conserved and returned to exhibit, and restoration of a third planetarium is underway. This talk will review the history of Barlow’s planetarium and the current state of the models that survive.
Waxing crescent moon with a well-defined terminator and a little Earthshine. Pastel sketch February 11th, 2008 200mm dob, 4.83 days. Deirdre Kelleghan
When the phrase "The Terminator" is mentioned in may conjour up ominous dark tones lurking within its meaning. A science fiction phrase where a cybernetic organism can ask for 'your clothes, your boots, and your motorcycle’ then ride off to alter the course of humanity. Or the visually rich line that demarks daytime on the moon's surface from night-time on the moon's surface.
The terminator is far from a straight line, it is ragged and uniquely fluid. Sunlight illuminates unevenly as it fills craters. Shadows form and transform during its progression across the lunar topography. Craters that penetrate the terminator and show their rims as glints of light in the blackness bring a tactile quality to a sketch. Lunar sketching in the area of the terminator often brings up a dilemma . When a sketch takes several hours, sometimes the terminator vista alters to offer a new and brightly lit feature. This crater or mountain only revealed as you finish. Do you put it in or not ? In general if it adds to the sketch yes, if it is a mediocre addition no.
Recently I came across the moon drawing above in one of my portfolios . The sketch includes a very well-defined terminator and a touch of earthshine. The drawing was devoid of information , no day, date or time was written on the sheet. A bit of a hunt provided the basics, but not all information was available and my memory yielded very little. Sometimes I might publish a sketch in a forum or group. All the information relating to the drawing can be online but not necessarily on the actual drawing. Note to self and others, always write the sketch details on the work.
Along the terminator visual richness pulsates with abundance. Take a terminator tour with your telescope , it doesn't matter if it's a small or large instrument. It doesn't matter if you do not know the features that you are seeing. Just enjoy the moon for itself, identity of features can come later. Contrast is sublime, blacks are pure, whites are sharp and exciting. Watch sunlight gain lunar ground on a waxing moon. Feast your eyes as mountains reveal themselves in complex craters. Shadows will alter before your eyes, giving or taking away from the appearance of craters.
Sometimes even a 98% moon terminator can bring joy and results. A previous blog about drawing along the terminator tells that story from Dunsink Observatory Dublin. Eddington Crater on the Moon
This column for The Tablet first ran in May 2006; we first ran it here at The Catholic Astronomer in 2015. It has been one of the more popular postings...
“Believing that God created the universe in six days is a form of superstitious paganism,” proclaimed a Scottish newspaper earlier this month [2006], citing as its authority no less than “the Vatican Astronomer, Guy Consolmagno.” I was as surprised as anyone; though I do worry that creationism can tend towards paganism, I don’t remember being so blunt. Well, he was careful not to put those words into quotation marks.
Hard to come up with a good image to illustrate this column, so here's a sky photo I took in Edinburgh many years later...
But even if it is an accurate statement of what I believe, does it qualify as news? I’m not a theologian, much less a spokesperson for the Vatican. I’m an astronomer who happens to be a Jesuit, who happens to work at the Vatican. Of course, I have my opinions on matters of theology, but are they any more newsworthy than the opinions of a punter at the pub about the prospects of his favorite football team?
I got the feeling, talking to the Scottish reporter, that my everyday Catholic approach to science and religion was a shock to his prejudices. Rather than accepting that his old preconceptions were wrong, he decided that what I was saying must be something new. And, judging from the response his article got, those prejudices (and shocks) must be rather widespread.
Those words made it into the “blogosphere,” that virtual world of the Internet where people pass around jokes, recipes, and outrages of the day. I received a dozen angry e-mails from creationists, upset that I had called them pagans; and another dozen from pagans, angry that I had called them creationists. So far, no one has spoken up for the superstitious.
But why would I think that there was a connection between the Genesis 1 description of creation, and paganism? Actually, for several reasons. For instance, Genesis 1 speaks of God forming the universe out of a pre-existing chaos; taken by itself, it implies that God only forms rather than creates. By contrast, the later book of Maccabees (2 Macc 7:28) speaks matter-of-factly about God truly creating, ex nihilo, out of nothing. The former vision is closer to a pagan one; the latter, Christianity. (The Genesis 1 description also ends up with a flat Earth covered by a dome, a point that most creationists appear to ignore.)
Likewise, insisting on a universe that needs a direct intervention of God to accomplish some things but not others (thus leaving telltale “thumbprints” of that intervention), reduces God to not much more than a functional equivalent of Jupiter, god of thunder, or Ceres, goddess of grain. The Christian belief of a supernatural God places Him normally outside of nature (that’s what makes the Incarnation so special), yet ultimately responsible for all of it. In essence, it’s all thumbprints.
The Old Testament talks about God’s creation in many places, not just Genesis 1. To understand where the truth lies, you need to account for all these different descriptions, to avoid misunderstandings due to word choices, translation errors, etc. And you need to recognize the settings in which they were written, to account for systematic biases as might arise from taking words intended for the ears of wise, if unscientific, pastoral peoples and reading them as if they were instructions from an engineering textbook.
One of the most important lessons a scientist learns is not to be too swayed by one data point. We know that every measurement is afflicted with both random and systematic errors. You take lots of data, and hope the random errors average out. You compare your results against known points of truth, to detect and account for any systematic tilt. And at the end of the day, you still recognize that your final result is, at most, only probably true.
This parallel with theology should not be surprising. Theology was the first science; it taught science the rules of reason.
The Moon appears in the southwestern predawn sky near Jupiter on May 1st, and makes it way between Mars and Saturn in the southern sky on May 5th.
Southern sky at 5:00 AM, May 1, 2018. Credit: Stellarium / Bob Trembley.
Southern sky at 5:00 AM, May 5, 2018. Credit: Stellarium / Bob Trembley.
Ursa Major (and the Big Dipper) are in the northwestern predawn sky, and Arcturus is bright in the western sky.
Western sky at 5:00 AM, May 5, 2018. Credit: Stellarium / Bob Trembley.
Venus remains low in the western sky near sunset.
Western sky at 9:00 PM, May 1, 2018. Credit: Stellarium / Bob Trembley.
Jupiter can be seen rising the in the eastern sky after sunset.
Eastern sky at 10:00 PM, May 1, 2018. Credit: Stellarium / Bob Trembley.
Jupiter will be at opposition on May 9th - its face will be fully illuminated by the Sun, and it will be visible all night long! Sidewalk astronomers from around the world do a collective dance of joy!
Jupiter at Opposition May 9 2018. Credit: NASA Eyes on the Solar System / Bob Trembley.
The Moon
The Moon May 1-7 2018. Visualizations by Ernie Wright
The Moon is a waning gibbous just past full; the Moon will be at third quarter on the 8th; May 7-10th would be good days to do some early morning sidewalk astronomy at schools!
The Sun
The Sun has been spot-free for 2 days. There are coronal holes at both poles, and a small hole on the equator. There is an area with quite a bit of coronal loop activity rotating out of view on the Sun's limb. SpaceWeather.com says: "Solar wind flowing from this equatorial coronal hole should reach Earth on May 5th or 6th." The solar wind speed is 409 km/sec, with a density of 4.0 protons/cm3.
Over the last couple days, several small prominences in the Sun's chromosphere appear and vanish all over the Sun's limb; the equatorial coronal hole appears as a dark smudge, and the area of coronal loop activity above appears as the bright orange region in the image below.
You can view the Sun in near real-time, in multiple frequencies here: SDO-The Sun Now.
You can create your own time-lapse movies of the Sun here: AIA/HMI Browse Data.
You can browse all the SDO images of the Sun from 2010 to the present here: Browse SDO archive.
In this diagram of the inner solar system, all of the fireball orbits intersect at a single point--Earth.
The Solar System
This is the position of the planets in the solar system:
Position of the planets in the inner solar system, May 1, 2018. Credit: NASA Eyes on the Solar System / Bob Trembley.
Position of the planets in the inner and middle solar system, May 1, 2018. Credit: NASA Eyes on the Solar System / Bob Trembley.
Exoplanets
Confirmed Exoplanets: 3,725 (4/26/2018)
Multi-Planet Systems: 613 (4/26/2018)
Kepler Candidate Exoplanets: 4,496 (8/31/2017)
TESS Candidate Exoplanets: 0 Data from the NASA Exoplanet Archive
The Transiting Exoplanet Survey Satellite (TESS) launched on April 18, 2018 on a SpaceX Falcon 9 rocket. TESS is the successor to the Kepler space telescope. From the TESS website:
TESS will discover thousands of exoplanets in orbit around the brightest stars in the sky. In a two-year survey of the solar neighborhood, TESS will monitor more than 200,000 stars for temporary drops in brightness caused by planetary transits. This first-ever spaceborne all-sky transit survey will identify planets ranging from Earth-sized to gas giants, around a wide range of stellar types and orbital distances. No ground-based survey can achieve this feat.
The Transiting Exoplanet Survey Satellite (TESS). Credit: NASA Eyes on the Solar System / Bob Trembley.
Stellarium: a free open source planetarium app for PC/MAC/Linux. It's a great tool for planning observing sessions. NASA Eyes on the Solar System: an immersive 3D solar system and space mission simulator - free for the PC /MAC. I maintain the unofficialNASA Eyes Facebook page.
What Is the Asteroid Belt?
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