Satellite view of Roden Crater, outside Flagstaff, Arizona. Credit: NASA
Imagine a volcano powerful enough to leave a massive crater in the Earth that could be seen from space. Now imagine that to a satellite observing it from above, the crater looked very much like an eyeball. And imagine that this same Wplace was bought by an internationally-renowned artist for the sake of turning it into the largest public art project in history.
This describes the Roden Crater perfectly, the remains of an extinct volcano located near Flagstaff, Arizona, on the edge of the Painted Desert that has since become an art project to James Turell – a man with some pretty unique artistic sensibilities!
Description:
The crater is a cinder-type volcanic cone – a hill that formed around a volcanic vent – that measures 3.2 km (2 miles) wide, 183 meters (600 feet) tall, and which is approximately 400,000 years old. Located northeast of the city of Flagstaff, Arizona, the volcano is part of the San Francisco Volcanic Field near the Painted Desert and the Grand Canyon.
James Turell’s Project:
In 1979, it was bought by artist James Turrell, who intends to turn it into a massive, open air work of art. James Turrell has long been famous in the art world for his unique take on creating art. Turrell purchased the land surrounding the crater – roughly 4.8 km (3 miles) across – with the intent of creating a naked-eye observatory at the inner core, specifically so guests could view and experience sky-light, solar, and celestial phenomena.
The Roden Crater, viewed from ground level at sunset. Credit: rodencrater.com
Turrell is known within the art community for the way his art plays with light and space. In 1974, he began conceiving of a project that would involve a natural setting, one that extended his explorations of light and space from the studio into the western landscape.
For this reason, he purchased the Roden Crater grounds with the hopes of using the types of visual phenomena that have excited and inspired humanity since the dawn of civilization – i.e. looking up at the stars – and creating a space where it could interplay with his artwork.
As Turrell has stated, he was also inspired by ancient observatories because of the way these places were geared to visual perception: “I admire Borobudur, Angkor Wat, Pagan, Machu Picchu, the Mayan pyramids, the Egyptian pyramids, Herodium, Old Sarum, Newgrange and the Maes Howe,” he said. “These places and structures have certainly influenced my thinking. These thoughts will find concurrence in Roden Crater.”
Eye-Witness Accounts:
This project has been the most massive public art undertaking to date. It has also sparked intense interest due to the fact that the observatory is restricted from the public. No one is allowed into the crater unless invited by the artist himself.
Typically though, those invited have made large contributions to the project or have commissioned other works of art from Turrell. Many well known art dealers and other important figures in the art world have seen the crater, and those who have witnessed it have described it as an incredible sight.
The Alpha Tunnel, one of many features that play into Turrell’s concepts of space and light. Credit: rodencrater.com
The desire to see the crater has even led some fans to trespass, which may involve hiking through the desert to get to the very remote location. Some have taken photos of the crater and posted them on the internet, although some of those visitors discourage people from taking the trip. Essentially, the location is potentially dangerous due to extremely isolation and the fact that it is far from any major roads.
James Turrell does not take a typical approach to art. After he bought the crater, he started excavating tons of earth – over 86,000 cubic meters (1.3 million cubic yards) to be exact – in order to shape the Crater Bowl and hollow out tunnels and chambers. He tried to make different viewing areas, so the light, astronomical features, and sky could be seen from inside the crater. Essentially, he tried to turn a space itself into art.
Visitors have commented on the bronze staircase leading out of the crater. A musician who visited the grounds also talked about playing the drums in a sound chamber and said that it was an amazing experience. Those who have been to the crater have not said too much about their experiences though, thus ensuring that the public is left to wonder about much of it.
The East Portal staircase, made out of bronze, which leads guests out of the crater. Credit: rodencrater.com
Completion:
Originally, the Roden Crater was supposed to be finished in the late 1980’s. However, the date of completion has been pushed back a number of times due to financial issues (among other problems) which caused construction to halt at different times. Recently, Turrell estimated that construction would be completed by 2011; but once again, there have been delays.
According to the Roden Crater website, the South Space – which is the last section waiting to be built – is in the final stages of engineering. A public opening for the project is anticipated in the next few years once this complete, but will be “dependent on fundraising and construction schedules.”
Some speculate that once the Roden Crater is finished it is going to be one of the hottest things in the art world. But don’t expect an invite anytime soon. If there’s one thing hot-ticket items like this are known for, it’s being inaccessible!
Be sure to enjoy this video of the Roden Crater and Turrell’s massive art project:
Astronomer Copernicus, or Conversations with God, by Matejko. Credit: frombork.art.pl/pl/
When it comes to understanding our place in the universe, few scientists have had more of an impact than Nicolaus Copernicus. The creator of the Copernican Model of the universe (aka. heliocentrism), his discovery that the Earth and other planets revolved the Sun triggered an intellectual revolution that would have far-reaching consequences.
In addition to playing a major part in the Scientific Revolution of the 17th and 18th centuries, his ideas changed the way people looked at the heavens, the planets, and would have a profound influence over men like Johannes Kepler, Galileo Galilei, Sir Isaac Newton and many others. In short, the “Copernican Revolution” helped to usher in the era of modern science.
Copernicus’ Early Life:
Copernicus was born on February 19th, 1473 in the city of Torun (Thorn) in the Crown of the Kingdom of Poland. The youngest of four children to a well-to-do merchant family, Copernicus and his siblings were raised in the Catholic faith and had many strong ties to the Church.
His older brother Andreas would go on to become an Augustinian canon, while his sister, Barbara, became a Benedictine nun and (in her final years) the prioress of a convent. Only his sister Katharina ever married and had children, which Copernicus looked after until the day he died. Copernicus himself never married or had any children of his own.
Nicolaus Copernicus portrait from Town Hall in Torun (Thorn), 1580. Credit: frombork.art.pl
Born in a predominately Germanic city and province, Copernicus acquired fluency in both German and Polish at a young age, and would go on to learn Greek and Italian during the course of his education. Given that it was the language of academia in his time, as well as the Catholic Church and the Polish royal court, Copernicus also became fluent in Latin, which the majority of his surviving works are written in.
Copernicus’ Education:
In 1483, Copernicus’ father (whom he was named after) died, whereupon his maternal uncle, Lucas Watzenrode the Younger, began to oversee his education and career. Given the connections he maintained with Poland’s leading intellectual figures, Watzenrode would ensure that Copernicus had great deal of exposure to some of the intellectual figures of his time.
Although little information on his early childhood is available, Copernicus’ biographers believe that his uncle sent him to St. John’ School in Torun, where he himself had been a master. Later, it is believed that he attended the Cathedral School at Wloclawek (located 60 km south-east Torun on the Vistula River), which prepared pupils for entrance to the University of Krakow – Watzenrode’s own Alma mater.
In 1491, Copernicus began his studies in the Department of Arts at the University of Krakow. However, he quickly became fascinated by astronomy, thanks to his exposure to many contemporary philosophers who taught or were associated with the Krakow School of Mathematics and Astrology, which was in its heyday at the time.
A comparison of the geocentric and heliocentric models of the universe. Credit: history.ucsb.edu
Copernicus’ studies provided him with a thorough grounding in mathematical-astronomical knowledge, as well as the philosophy and natural-science writings of Aristotle, Euclid, and various humanist writers. It was while at Krakow that Copernicus began collecting a large library on astronomy, and where he began his analysis of the logical contradictions in the two most popular systems of astronomy.
These models – Aristotle’s theory of homocentric spheres, and Ptolemy’s mechanism of eccentrics and epicycles – were both geocentric in nature. Consistent with classical astronomy and physics, they espoused that the Earth was at the center of the universe, and that the Sun, the Moon, the other planets, and the stars all revolved around it.
Before earning a degree, Copernicus left Krakow (ca. 1495) to travel to the court of his uncle Watzenrode in Warmia, a province in northern Poland. Having been elevated to the position of Prince-Bishop of Warmia in 1489, his uncle sought to place Copernicus in the Warmia canonry. However, Copernicus’ installation was delayed, which prompted his uncle to send him and his brother to study in Italy to further their ecclesiastic careers.
In 1497, Copernicus arrived in Bologna and began studying at the Bologna University of Jurists’. While there, he studied canon law, but devoted himself primarily to the study of the humanities and astronomy. It was also while at Bologna that he met the famous astronomer Domenico Maria Novara da Ferrara and became his disciple and assistant.
An illustration of the Ptolemaic geocentric system by Portuguese cosmographer and cartographer Bartolomeu Velho, 1568. Credit: bnf.fr
Over time, Copernicus’ began to feel a growing sense of doubt towards the Aristotelian and Ptolemaic models of the universe. These included the problematic explanations arising from the inconsistent motion of the planets (i.e. retrograde motion, equants, deferents and epicycles), and the fact that Mars and Jupiter appeared to be larger in the night sky at certain times than at others.
Hoping to resolve this, Copernicus used his time at the university to study Greek and Latin authors (i.e. Pythagoras, Cicero, Pliny the Elder, Plutarch, Heraclides and Plato) as well as the fragments of historic information the university had on ancient astronomical, cosmological and calendar systems – which included other (predominantly Greek and Arab) heliocentric theories.
In 1501, Copernicus moved to Padua, ostensibly to study medicine as part of his ecclesiastical career. Just as he had done at Bologna, Copernicus carried out his appointed studies, but remained committed to his own astronomical research. Between 1501 and 1503, he continued to study ancient Greek texts; and it is believed that it was at this time that his ideas for a new system of astronomy – whereby the Earth itself moved – finally crystallized.
The Copernican Model (aka. Heliocentrism):
In 1503, having finally earned his doctorate in canon law, Copernicus returned to Warmia where he would spend the remaining 40 years of his life. By 1514, he began making his Commentariolus (“Little Commentary”) available for his friends to read. This forty-page manuscript described his ideas about the heliocentric hypothesis, which was based on seven general principles.
These seven principles stated that: Celestial bodies do not all revolve around a single point; the center of Earth is the center of the lunar sphere—the orbit of the moon around Earth; all the spheres rotate around the Sun, which is near the center of the Universe; the distance between Earth and the Sun is an insignificant fraction of the distance from Earth and Sun to the stars, so parallax is not observed in the stars; the stars are immovable – their apparent daily motion is caused by the daily rotation of Earth; Earth is moved in a sphere around the Sun, causing the apparent annual migration of the Sun; Earth has more than one motion; and Earth’s orbital motion around the Sun causes the seeming reverse in direction of the motions of the planets.
Andreas Cellarius’s illustration of the Copernican system, from the Harmonia Macrocosmica (1708). Credit: Public Domain
Thereafter he continued gathering data for a more detailed work, and by 1532, he had come close to completing the manuscript of his magnum opus – De revolutionibus orbium coelestium(On the Revolutions of the Heavenly Spheres). In it, he advanced his seven major arguments, but in more detailed form and with detailed computations to back them up.
However, due to fears that the publication of his theories would lead to condemnation from the church (as well as, perhaps, worries that his theory presented some scientific flaws) he withheld his research until a year before he died. It was only in 1542, when he was near death, that he sent his treatise to Nuremberg to be published.
Copernicus’ Death:
Towards the end of 1542, Copernicus suffered from a brain hemorrhage or stroke which left him paralyzed. On May 24th, 1543, he died at the age of 70 and was reportedly buried in the Frombork Cathedral in Frombork, Poland. It is said that on the day of his death, May 24th 1543 at the age of 70, he was presented with an advance copy of his book, which he smiled upon before passing away.
In 2005, an archaeological team conducted a scan of the floor of Frombork Cathedral, declaring that they had found Copernicus’ remains. Afterwards, a forensic expert from the Polish Police Central Forensic Laboratory used the unearthed skull to reconstruct a face that closely resembled Copernicus’ features. The expert also determined that the skull belonged to a man who had died around age 70 – Copernicus’ age at the time of his death.
These findings were backed up in 2008 when a comparative DNA analysis was made from both the remains and two hairs found in a book Copernicus was known to have owned (Calendarium Romanum Magnum, by Johannes Stoeffler). The DNA results were a match, proving that Copernicus’ body had indeed been found.
Copernicus’ 2010 grave in Frombork Cathedral, acknowledging him as a church canon and the father of heliocentricism. Credit: Wikipedia/Holger Weinandt
On May 22nd, 2010, Copernicus was given a second funeral in a Mass led by Józef Kowalczyk, the former papal nuncio to Poland and newly named Primate of Poland. Copernicus’ remains were reburied in the same spot in Frombork Cathedral, and a black granite tombstone (shown above) now identifies him as the founder of the heliocentric theory and also a church canon. The tombstone bears a representation of Copernicus’ model of the solar system – a golden sun encircled by six of the planets.
Copernicus’ Legacy:
Despite his fears about his arguments producing scorn and controversy, the publication of his theories resulted in only mild condemnation from religious authorities. Over time, many religious scholars tried to argue against his model, using a combination of Biblical canon, Aristotelian philosophy, Ptolemaic astronomy, and then-accepted notions of physics to discredit the idea that the Earth itself would be capable of motion.
However, within a few generation’s time, Copernicus’ theory became more widespread and accepted, and gained many influential defenders in the meantime. These included Galileo Galilei (1564-1642), who’s investigations of the heavens using the telescope allowed him to resolve what were seen at the time as flaws in the heliocentric model.
These included the relative changes in the appearances of Mars and Jupiter when they are in opposition vs. conjunction to the Earth. Whereas they appear larger to the naked eye than Copernicus’ model suggested they should, Galileo proved that this is an illusion caused by the behavior of light at a distance, and can be resolved with a telescope.
1973 Federal Republic of Germany 5-mark silver coin commemorating 500th anniversary of Copernicus’ birth. Credit: Wikipedia/Berlin-George
Through the use of the telescope, Galileo also discovered moons orbiting Jupiter, Sunspots, and the imperfections on the Moon’s surface, all of which helped to undermine the notion that the planets were perfect orbs, rather than planets similar to Earth. While Galileo’s advocacy of Copernicus’ theories resulted in his house arrest, others soon followed.
German mathematician and astronomer Johannes Kepler (1571-1630) also helped to refine the heliocentric model with his introduction of elliptical orbits. Prior to this, the heliocentric model still made use of circular orbits, which did not explain why planets orbited the Sun at different speeds at different times. By showing how the planet’s sped up while at certain points in their orbits, and slowed down in others, Kepler resolved this.
In addition, Copernicus’ theory about the Earth being capable of motion would go on to inspire a rethinking of the entire field of physics. Whereas previous ideas of motion depended on an outside force to instigate and maintain it (i.e. wind pushing a sail) Copernicus’ theories helped to inspire the concepts of gravity and inertia. These ideas would be articulated by Sir Isaac Newton, who’s Principia formed the basis of modern physics and astronomy.
Today, Copernicus is honored (along with Johannes Kepler) by the liturgical calendar of the Episcopal Church (USA) with a feast day on May 23rd. In 2009, the discoverers of chemical element 112 (which had previously been named ununbium) proposed that the International Union of Pure and Applied Chemistry rename it copernicum (Cn) – which they did in 2011.
Mosaic image of the Copernicus Crater on the Moon, taken by the Lunar Reconnaissance Orbiter, . Credit: NASA/LRO
In 1973, on the 500th anniversary of his birthday, the Federal Republic of Germany (aka. West Germany) issued a 5 Mark silver coin (shown above) that bore Copernicus’ name and a representation of the heliocentric universe on one side.
In August of 1972, the Copernicus– an Orbiting Astronomical Observatory created by NASA and the UK’s Science Research Council – was launched to conduct space-based observations. Originally designated OAO-3, the satellite was renamed in 1973 in time for the 500th anniversary of Copernicus’ birth. Operating until February of 1981, Copernicus proved to be the most successful of the OAO missions, providing extensive X-ray and ultraviolet information on stars and discovering several long-period pulsars.
Two craters, one located on the Moon, the other on Mars, are named in Copernicus’ honor. The European Commission and the European Space Agency (ESA) is currently conducting the Copernicus Program. Formerly known as Global Monitoring for Environment and Security (GMES), this program aims at achieving an autonomous, multi-level operational Earth observatory.
On February 19th, 2013, the world celebrated the 540th anniversary of Copernicus’ birthday. Even now, almost five and a half centuries later, he is considered one of the greatest astronomers and scientific minds that ever lived. In addition to revolutionizing the fields of physics, astronomy, and our very concept of the laws of motion, the tradition of modern science itself owes a great debt to this noble scholar who placed the truth above all else.
Voyager 2's highest-resolution image of Titania shows moderately cratered plains, enormous rifts and long scarps. Near the bottom, a region of smoother plains including the crater Ursula is split by the graben Belmont Chasma. Credit: NASA
Thanks to the Voyager missions, which passed through the outer Solar system in the late 1970s and early 1980s, scientists were able to get the first close look at Uranus and its system of moons. Like all of the Solar Systems’ gas giants, Uranus has many fascinating satellites. In fact, astronomers can now account for 27 moons in orbit around the teal-colored giant.
Of these, none are greater in size, mass, or surface area than Titania, which was appropriately named. As one of the first moon’s to be discovered around Uranus, this heavily cratered and scarred moon takes it name from the fictional Queen of the Fairies in Shakespeare’s A Midsummer Night’s Dream.
Discovery and Naming:
Titania was discovered by William Herschel on January 11th, 1787, the English astronomer who had discovered Uranus in 1781. The discovery was also made on the same day that he discovered Oberon, Uranus’ second-largest moon. Although Herschel reported observing four other moons at the time, the Royal Astronomical Society would later determine that this claim was spurious.
It would be almost five decades after Titania and Oberon was discovered that an astronomer other than Herschel would observe them. In addition, Titania would be referred to as “the first satellite of Uranus” for many years – or by the designation Uranus I, which was given to it by William Lassell in 1848.
A montage of Uranus’s moons. Image credit: NASA
By 1851, Lassell began to number all four known satellites in order of their distance from the planet by Roman numerals, at which point Titania’s designation became Uranus III. By 1852, Herschel’s son John, and at the behest of Lassell himself, suggested the moon’s name be changed to Titania, the Queen of the Fairies in A Midsummer Night’s Dream. This was consistent with all of Uranus’ satellites, which were given names from the works of William Shakespeare and Alexander Pope.
Size, Mass and Orbit:
With a diameter of 1,578 kilometers, a surface area of 7,820,000 km² and a mass of 3.527±0.09 × 1021 kg, Titania is the largest of Uranus’ moons and the eighth largest moon in the Solar System. At a distance of about 436,000 km (271,000 mi), Titania is also the second farthest from the planet of the five major moons.
Titania’s moon also has a small eccentricity and is inclined very little relative to the equator of Uranus. It’s orbital period, which is 8.7 days, is also coincident with it’s rotational period. This means that Titania is a synchronous (or tidally-locked) satellite, with one face always pointing towards Uranus at all times.
Because Uranus orbits the Sun on its side, and its moons orbit the planet’s equatorial plane, they are all subject to an extreme seasonal cycle, where the northern and southern poles experience 42 years of either complete darkness or complete sunlight.
Uranus and its five major moons, with Titania being the farthest left. Credit: space.com
Composition:
Scientists believe Titania is composed of equal parts rock (which may include carbonaceous materials and organic compounds) and ice. This is supported by examinations that indicate that Titania has an unusually high-density for a Uranian satellite (1.71 g/cm³). The presence of water ice is supported by infrared spectroscopic observations made in 2001–2005, which have revealed crystalline water ice on the surface of the moon.
It is also believed that Titania is differentiated into a rocky core surrounded by an icy mantle. If true, this would mean that the core’s radius is approx. 520 km (320 mi), which would mean the core accounts for 66% of the radius of the moon, and 58% of its mass.
As with Uranus’ other major moons, the current state of the icy mantle is unknown. However, if the ice contains enough ammonia or other antifreeze, Titania may have a liquid ocean layer at the core-mantle boundary. The thickness of this ocean, if it exists, is up to 50 km (31 mi) and its temperature is around 190 K.
Naturally, it is unlikely that such an ocean could support life. But assuming this ocean supports hydrothermal vents on its floor, it is possible life could exist in small patches close to the core. However, the internal structure of Oberon depends heavily on its thermal history, which is poorly known at present.
Voyager 2:
The only direct observations made of Titania were conducted by the Voyager 2 space probe, which photographed the moon during its flyby of Uranus in January 1986. These images covered about 40% of the surface, but only 24% was photographed with the precision required for geological mapping.
Voyager’s flyby of Titania coincided with the southern hemisphere’s summer solstice, when nearly the entire northern hemisphere was unilluminated. As with the other major moon’s of Uranus, this prevented the surface from being mapped in any detail. No other spacecraft has visited the Uranian system or Titania before or since, and no mission is planned in the foreseeable future.
Interesting Facts:
Titania is intermediate in terms of brightness, occupying a middle spot between the dark moons of Oberon and Umbriel and the bright moons of Ariel and Miranda. It’s surface is generally red in color (less so than Oberon), except where fresh impact have taken place, which have left the surface blue in color. The surface of Titania is less heavily cratered than the surface of either Oberon or Umbriel, suggesting that its surface is much younger.
Like all of Uranus’ major moons, it’s geology is influenced by a combination of impact craters and endogenic resurfacing. Whereas the former acted over the moon’s entire history and influenced all its surfaces, the latter processes were mainly active following the moon’s formation and resulted in a smoothing out of its features – hence the low number of present-day impact craters.
Overall, scientists have recognized three classes of geological feature on Titania. These include craters, faults (or scarps) and what are known as grabens (sometimes called canyons). Titania’s craters range in diameter from a few kilometers to 326 kilometers – in the case of the largest known crater, Gertrude. Titania’s surface is also intersected by a system of enormous faults (scarps); and in some places, two parallel scarps mark depressions in the satellite’s crust, forming grabens (aka. canyons).
Voyager 2 image of Titania’s southern hemisphere. Credit: NASA/JPL
The grabens on Titania range in diameter from 20 to 50 kilometers (12–31 mi) and in a relief (i.e. depth) from 2 to 5 km. The most prominent graben on Titania is the Messina Chasma, which runs for about 1,500 kilometers (930 mi) from the equator almost to the south pole. The grabens are probably the youngest geological features on Titania, since they cut through all craters and even the smooth plains.
Like Oberon, the surface features on Titania have been named after characters in works by Shakespeare, with all of the physical features are named after female characters. For instance, the crater Gertrude is named after Hamlet’s mother, while other craters – Ursula, Jessica, and Imogen – are named after characters from Much Ado About Nothing, The Merchant of Venice, and Cymebline, respectively.
Interestingly, the presence of carbon dioxide on the surface suggests that Titania may also have a tenuous seasonal atmosphere of CO², much like that of the Jovian moon Callisto. Other gases, like nitrogen or methane, are unlikely to be present, because Titania’s weak gravity could not prevent them from escaping into space.
Like all of Uranus’ moons, much remains to be discovered about this most-massive of her satellites. In the coming years, one can only hope that NASA, the ESA, or other space agencies decide that another Voyager-like mission is need to the outer Solar System. Until such time, Uranus and the many moons that orbit it will continue to keep secrets from us.
So, just how do we keep our space stations, ships and astronauts from being riddled with holes from all of the space junk in orbit around Earth?
We revel in the terror grab bag of all the magical ways to get snuffed in space. Almost as much as we celebrate the giant brass backbones of the people who travel there.
We’ve already talked about all the scary ways that astronauts can die in space. My personal recurring “Hail Mary full of grace, please don’t let me die in space” nightmare is orbital debris.
We’re talking about a vast collection of spent rockets, dead satellites, flotsam, jetsam, lagan and derelict. It’s not a short list. NASA figures there are 21,000 bits of junk bigger than 10 cm, 500,000 particles between 1 and 10 cm, and more than 100 million smaller than 1 cm. Sound familiar, humans? This is our high tech, sci fi great Pacific garbage patch.
Sure, a tiny rivet or piece of scrap foil doesn’t sound very dangerous, but consider the fact that astronauts are orbiting the Earth at a velocity of about 28,000 km/h. And the Tang packets, uneaten dehydrated ice cream, and astronaut poops are also traveling at 28,000 km/h. Then think about what happens when they collide. Yikes… or yuck.
Here’s the International Space Station’s solar array. See that tiny hole? Embiggen and clarinosticate! That’s a tiny puncture hole made in the array by a piece of orbital crap.
The whole station is pummeled by tiny pieces of space program junk drawer contents. Back when the Space Shuttle was flying, NASA had to constantly replace their windows because of the damage they were experiencing from the orbital equivalent of Dennis the Menace hurling paint chips, fingernail clippings, and frozen scabs.
That’s just little pieces of paint. What can NASA do to keep Sandra Bullock safe from the larger, more dangerous chunks that could tear the station a new entry hatch?
For starters, NASA and the US Department of Defense are constantly tracking as much of the orbital debris that they can. They know the position of every piece of debris larger than a softball. Which I think, as far as careers go, would be grossly underestimated for its coolness and complexity at a cocktail party.
Artist’s impression of debris in low Earth orbit. Credit: ESA
“What do you do for a living?”
“Me, oh, I’m part of the program which tracks orbital debris to keep astronauts safe.”
“So…you track our space garbage?”
“Uh, actually, never mind, I’m an accountant.”
Furthermore, they’re tracking everything in low Earth orbit – where the astronauts fly – down to a size of 5 cm. That’s 21,000 discrete objects.
NASA then compares the movements of all these objects and compares it to the position of the Space Station. If there’s any risk of a collision, NASA takes preventative measures and moves the Space Station to avoid the debris.
The ISS has thrusters of its own, but it can also use the assistance of spacecraft which are docked to it at the time, such as a Russian Soyuz capsule.
NASA is ready to make these maneuvers at a moment’s notice if necessary, but often they’ll have a few days notice, and give the astronauts time to prepare. Plus, who doesn’t love a close call?
For example, in some alerts, the astronauts have gotten into their Soyuz escape craft, ready to abandon the Station if there’s a catastrophic impact. And if they have even less warning, the astronauts have to just hunker down in some of the Station’s more sturdy regions and wait out the debris flyby.
The Iridium constellation – a robust satellite network (Iridium)
This isn’t speculation and overcautious nannying on NASA’s part. In 2009 an Iridium communications satellite was smashed by a dead Russian Kosmos-2251 military satellite. The collision destroyed both satellites instantly. As icing on this whirling, screaming metallic orbital-terror-cake, it added 2,000 new chunks of debris to the growing collection.
Most material was in a fairly low orbit, and much of it has already been slowed down by the Earth’s atmosphere and burned up.
This wasn’t the first time two star-crossed satellites with a love that could-not-be had a shrapnel fountain suicide pact, and I promise it won’t be the last. Each collision adds to the total amount of debris in orbit, and increases the risk of a run-away cascade of orbital collisions.
We should never underestimate the bravery and commitment of astronauts. They strap themselves to massive explosion tubes and weather the metal squalls of earth orbit in tiny steel life-rafts. So, would you be willing to risk all that debris for a chance to fly in orbit? Tell us in the comments below.
The terrestrial planets of our Solar System at approximately relative sizes. From left, Mercury, Venus, Earth and Mars. Credit: Lunar and Planetary Institute
In studying our Solar System over the course of many centuries, astronomers learned a great deal about the types of planets that exist in our universe. This knowledge has since expanded thanks to the discovery of extrasolar planets, many of which are similar to what we have observed here at home.
For example, while hundreds of gas giants of varying size have been detected (which are easier to detect because of their size), numerous planets have also been spotted that are similar to Earth – aka. “Earth-like”. These are what is known as terrestrial planets, a designation which says a lot about a planet how it came to be.
Definition:
Also known as a telluric or rocky planet, a terrestrial planet is a celestial body that is composed primarily of silicate rocks or metals and has a solid surface. This distinguishes them from gas giants, which are primarily composed of gases like hydrogen and helium, water, and some heavier elements in various states.
The term terrestrial planet is derived from the Latin “Terra” (i.e. Earth). Terrestrial planets are therefore those that are “Earth-like”, meaning they are similar in structure and composition to planet Earth.
Artist’s concept for the range of Earth-like extrasolar planets that have been discovered in recent years. Credit: NASA/JPL
Composition and Characteristics:
All terrestrial planets have approximately the same type of structure: a central metallic core composed of mostly iron, with a surrounding silicate mantle. Such planets have common surface features, which include canyons, craters, mountains, volcanoes, and other similar structures, depending on the presence of water and tectonic activity.
Terrestrial planets also have secondary atmospheres, which are generated through volcanism or comet impacts. This also differentiates them from gas giants, where the planetary atmospheres are primary and were captured directly from the original solar nebula.
Terrestrial planets are also known for having few or no moons. Venus and Mercury have no moons, while Earth has only the one (the Moon). Mars has two satellites, Phobos and Deimos, but these are more akin to large asteroids than actual moons. Unlike the gas giants, terrestrial planets also have no planetary ring systems.
The Earth’s interior structure, shown here as consisting of multiple “layers”. Credit: discovermagazine.com
Solar Terrestrial Planets:
All those planets found within the Inner Solar System – Mercury, Venus, Earth and Mars – are examples of terrestrial planets. Each are composed primarily of silicate rock and metal, which is differentiated between a dense, metallic core and a silicate mantle. The Moon is similar, but has a much smaller iron core.
Io and Europa are also satellites that have internal structures similar to that of terrestrial planets. In the case of the former, models of the moon’s composition suggest that the mantle is composed primarily of silicate rock and iron, which surrounds a core of iron and iron sulphide. Europa, on the other hand, is believed to have an iron core that is surrounded by an outer layer of water.
Dwarf planets, like Ceres and Pluto, and other large asteroids are similar to terrestrial planets in the fact that they do have a solid surface. However, they differ in that they are, on average, composed of more icy materials than rock.
Extrasolar Terrestrial Planets:
Most of the planets detected outside of the Solar System have been gas giants, owing to the fact that they are easier to spot. However, since 2005, hundreds of potentially terrestrial extrasolar planets have been found – mainly by the Kepler space mission. Most of these have been what is known as “super-Earths” (i.e. planets with masses between Earth’s and Neptune’s).
Examples of extrasolar terrestrial planets include Gliese 876 d, a planet that has a mass 7 to 9 times that of Earth. This planet orbits the red dwarf Gliese 876, which is located approximately 15 light years from Earth. The existence of three (or possibly four) terrestrial exoplanets was also confirmed between 2007 and 2010 in the Gliese 581 system, another red dwarf roughly 20 light years from Earth.
The smallest of these, Gliese 581 e, is only about 1.9 Earth masses, but orbits very close to the star. Two others, Gliese 581 c and Gliese 581 d, as well as a proposed fourth planet (Gliese 581 g) are more-massive super-Earths orbiting in or close to the habitable zone of the star. If true, this could mean that these worlds are potentially habitable Earth-like planets.
The first confirmed terrestrial exoplanet, Kepler-10b – a planet with between 3 and 4 Earth masses and located some 460 light years from Earth – was found in 2011 by the Kepler space mission. In that same year, the Kepler Space Observatory team released a list of 1235 extrasolar planet candidates, including six that were “Earth-size” or “super-Earth-size” (i.e. less than 2 Earth radii) and which were located within their stars’ habitable zones.
Since then, Kepler has discovered hundreds of planets ranging from Moon-sized to super-Earths, with many more candidates in this size range. As of January, 2013, 2740 planet candidates have been discovered.
Categories:
Scientists have proposed several categories for classifying terrestrial planets. Silicate planets are the standard type of terrestrial planet seen in the Solar System, which are composed primarily of a silicon-based rocky mantle and a metallic (iron) core.
Iron planets are a theoretical type of terrestrial planet that consists almost entirely of iron and therefore has a greater density and a smaller radius than other terrestrial planets of comparable mass. Planets of this type are believed to form in the high-temperature regions close to a star, and where the protoplanetary disk is rich in iron. Mercury is possible example, which formed close to our Sun and has a metallic core equal to 60–70% of its planetary mass.
Coreless planets are another theoretical type of terrestrial planet, one that consists of silicate rock but has no metallic core. In other words, coreless planets are the opposite of an iron planet. Coreless planets are believed to form farther from the star where volatile oxidizing material is more common. Though the Solar System has no coreless planets, chondrite asteroids and meteorites are common.
And then there are Carbon planets (aka. “diamond planets”), a theoretical class of planets that are composed of a metal core surrounded by primarily carbon-based minerals. Again, the Solar System has no planets that fit this description, but has an abundance of carbonaceous asteroids.
Until recently, everything scientists knew about planets – which included how they form and the different types that exist – came from studying our own Solar System. But with the explosion that has taken place in exoplanet discovery in the past decade, what we know about planets has grown significantly.
For one, we have come to understand that the size and scale of planets is greater than previously thought. What’s more, we’ve seen for the first time that many planets similar to Earth (which could also include being habitable) do in fact exist in other Solar Systems.
Who knows what we will find once we have the option of sending probes and manned missions to other terrestrial planets?
Astronomy Cast has episodes on the terrestrial planets including Mars, and an interview with Darin Ragozzine, one of the Kepler Space Mission scientists.
Bootprint in the lunar regolith left behing by the Apollo 11 crew. Credit: NASA
On July 20th, 1969, history was made when men walked on the Moon for the very first time. The result of almost a decade’s worth of preparation, billions of dollars of investment, strenuous technical development and endless training, the Moon Landing was the high point of the Space Age and the single greatest accomplishment ever made.
Because they were the first men to walk on the Moon, Neil Armstrong and Edwin “Buzz” Aldrin are forever written in history. And since that time, only ten men have had the honor of following in their footsteps. But with plans to return to the Moon, a new generation of lunar explorers is sure to be coming soon. So just who were these twelve men who walked on the Moon?
Prelude to the Moon Landing:
Before the historic Apollo 11 mission and Moon Landing took place, NASA conducted two manned missions to test the Apollo spacecraft and the Saturn V rockets that would be responsible for bringing astronauts to the lunar surface. The Apollo 8 mission – which took place on Dec. 21st, 1968 – would be the first time a spacecraft left Earth orbit, orbited the Moon, and then returned safely to Earth.
During the mission, the three-astronaut crew – Commander Frank Borman, Command Module Pilot James Lovell, and Lunar Module Pilot William Anders – spent three days flying to the Moon, then completed 10 circumlunar orbits in the course of 20 hours before returning to Earth on Dec. 27th.
During one of their lunar orbits, the crew made a Christmas Eve television broadcast where they read the first 10 verses from the Book of Genesis. At the time, the broadcast was the most watched TV program in history, and the crew was named Time magazine’s “Men of the Year” for 1968 upon their return.
On May 18th, 1969, in what was described as a “dress rehearsal” for a lunar landing, the Apollo 10 mission blasted off. This involved testing all the components and procedures that would be used for the sake of the Moon Landing.
The crew – which consisted of Thomas P. Stafford as Commander, John W. Young as the Command Module Pilot, and Eugene A. Cernan as the Lunar Module Pilot – flew to the Moon and passed within 15.6 km (8.4 nautical miles) of the lunar surface before returning home.
Apollo 11:
On July 16th, 1969, at 13:32:00 UTC (9:32:00 a.m. EDT local time) the historic Apollo 11 mission took off from the Kennedy Space Center in Florida. The crew consisted of Neil Armstrong as the Commander, Michael Collins as the Command Module Pilot), and Edwin “Buzz” Aldrin as the Lunar Module Pilot.
Neil Armstrong and Buzz Aldrin plant the US flag on the Lunar Surface during the first human moonwalk in history on July 20, 1969. Credit: NASA
On July 19th at 17:21:50 UTC, Apollo 11 passed behind the Moon and fired its service propulsion engine to enter lunar orbit. On the following day, the Lunar Module Eagle separated from the Command Module Columbia, and Armstrong and Aldrin commenced their Lunar descent.
Taking manual control of the Lunar Module, Armstrong brought them down to a landing spot in the Sea of Tranquility, and then announced their arrival by saying: “Houston, Tranquility Base here. The Eagle has landed.” After conducting post-landing checks and depressurizing the cabin, Armstrong and Aldrin began descending the ladder to the lunar surface.
When he reached the bottom of the ladder, Armstrong said: “I’m going to step off the LEM now” (Lunar Excursion Module). He then turned and set his left boot on the surface of the Moon at 2:56 UTC July 21st, 1969, and spoke the famous words “That’s one small step for [a] man, one giant leap for mankind.”
About 20 minutes after the first step, Aldrin joined Armstrong on the surface, and the two men began conducting the planned surface operations. In so doing, they became the first and second humans to set foot on the Moon.
Apollo 12:
Four months later, on November 14th, 1969, the Apollo 12 mission took off from the Kennedy Space Center. Crewed by Commander Charles “Pete” Conrad, Lunar Module Pilot Alan L. Bean and Command Module Pilot Richard F. Gordon, this mission would be the second time astronauts would walk on the Moon.
Ten days later, the Lunar Module touched down without incident on the southeastern portion of the Ocean of Storms. When Conrad and Bean reached the lunar surface, Bean’s first words were: “Whoopie! Man, that may have been a small one step for Neil, but that’s a long one for me.” In the course of conducting a Extra-Vehicular Activities (EVAs), the two astronauts became the third and fourth men to walk on the Moon.
The crew also brought the first color television camera to film the mission, but transmission was lost after Bean accidentally destroyed the camera by pointing it at the Sun. On one of the two EVAs, the crew visited the Surveyor3 unmanned probe, which had landed in the Ocean of Storms on April 20th, 1967. The mission ended on November 24th with a successful splashdown.
Pete Conrad descends from the Lunar Module (LM). Credit: NASA
Apollo 14:
TheApollo 13 mission was intended to be the third lunar landing; but unfortunately, the explosion of the oxygen tank aboard the Service Module forced the crew to abort the landing. Using the Lunar Module as a “lifeboat”, the crew executed a single loop around the Moon before safely making it back to Earth.
As a result, Apollo 14 would be the third manned mission to the lunar surface, crewed by veteran Alan Shepard (as Commander), Stuart Roosa as Command Module Pilot, and Edgar Mitchell as Lunar Module Pilot. The mission launched on January 31st, 1971 and Shepard and Mitchell made their lunar landing on February 5th in the Fra Mauro formation, which had originally been targeted for the Apollo 13 mission.
During two lunar EVAs, Shepard and Mitchell became the fifth and sixth men to walk on the Moon. They also collected 42 kilograms (93 lb) of Moon rocks and conducted several surface experiments – which including seismic studies. During the 33 hours they spent on the Moon (9½ hours of which were dedicated to EVAs), Shepard famously hit two golf balls on the lunar surface with a makeshift club he had brought from Earth.
Shepard poses next to the American flag on the Moon during Apollo 14. Credit: NASA
Apollo 15:
The seventh and eight men to walk on the Moon were David R. Scott, and James B. Irwin – the Commander and Lunar Module Pilot of the Apollo 15 mission. This mission began on July 26th, 1971, and landed near Hadley rille – in an area of the Mare Imbrium called Palus Putredinus (Marsh of Decay) – on August 7th.
The mission was the first time a crew explored the lunar surface using a Lunar Vehicular Rover (LVR), which allowed them to travel farther and faster from the Lunar Module (LM) than was ever before possible. In the course of conducting multiple EVAs, the crew collected 77 kilograms (170 lb) of lunar surface material.
While in orbit, the crew also deployed a sub-satellite, and used it and the Scientific Instrument Module (SIM) to study the lunar surface with a panoramic camera, a gamma-ray spectrometer, a mapping camera, a laser altimeter, and a mass spectrometer. At the time, NASA hailed the mission as “the most successful manned flight ever achieved.”
Image from Apollo 15, taken by Commander David Scott at the end of EVA-1. Credit: NASA
Apollo 16:
It was during the Apollo 16 mission – the penultimate manned lunar mission – that the ninth and tenth men were to walk on the Moon. After launching from the Kennedy Space Center on April 16th, 1972, the mission arrived on the lunar surface by April 21st. Over the course of three days, Commander John Young and Lunar Module Pilot Charles Duke conducted three EVAs, totaling 20 hours and 14 minutes on the lunar surface.
The mission was also the second occasion where an LVR was used, and Young and Duke collected 95.8 kilograms (211 lb) of lunar samples for return to Earth, while Command Module Pilot Ken Mattingly orbited in the Command/Service Module (CSM) above to perform observations.
Apollo 16’s landing spot in the highlands was chosen to allow the astronauts to gather geologically older lunar material than the samples obtained in the first four landings. Because of this, samples from the Descartes Cayley Formations disproved a hypothesis that the formations were volcanic in origin. The Apollo 16 crew also released a subsatellite from the Service Module before breaking orbit and returning to Earth, making splashdown by April 27th.
John W. Young standing next to the LM Orion during the Apollo 16 mission, April 21, 1972. Credit: NASA
Apollo 17:
The last of the Apollo missions, and the final time astronauts would set foot on the moon, began at 12:33 am Eastern Standard Time (EST) on December 7th, 1972. The mission was crewed by Eugene Cernan, Ronald Evans, and Harrison Schmitt – in the roles of Commander, Command Module Pilot and Lunar Module Pilot, respectively.
After reaching the lunar surface, Cernan and Schmitt conducted EVAs and became the eleventh and twelve men to walk on the lunar surface. The mission also broke several records set by previous flights, which included the longest manned lunar landing flight, the longest total lunar surface extravehicular activities, the largest lunar sample return, and the longest time in lunar orbit.
While Evans remained in lunar orbit above in the Command/Service Module (CSM), Cernan and Schmitt spent just over three days on the lunar surface in the Taurus–Littrow valley, conducting three periods of extra-vehicular activity with an LRV, collecting lunar samples and deploying scientific instruments. Cernan, After an approximately 12 day mission, Evans, and Schmitt returned to Earth.
Astronaut Eugene A. Cernan, commander of the Apollo 17 mission, using a Lunar Roving Vehicle (LRV) for an EVA on December 11th 1972. Credit: NASA
Apollo 17 remains the most recent manned Moon mission and also the last time humans have traveled beyond low Earth orbit. Until such time as astronauts begin to go to the Moon again (or manned missions are made to Mars) these twelve men – Neil Armstrong, Edwin “Buzz” Aldrin, Charles “Pete” Conrad, Alan L. Bean, Alan Shepard, Edgar Mitchell, David R. Scott, James B. Irwin, John Young, Charles Duke, Eugene Cernan, and Harrison Schmitt – will remain the only human beings to ever walk on a celestial body other than Earth.
We’ve found hundreds of exoplanets in the galaxy. But only a few of them have just the right combination of factors to hold life like Earth’s.
The weather in your hometown is downright uninhabitable. There’s scorching heatwaves, annual tyhpoonic deluges, and snow deep enough to bury a corn silo.
The bad news is planet Earth is the only habitable place we know of in the entire Universe. Also, are the Niburians suffering from Niburian made climate change? Only Niburian Al Gore can answer that question.
We as a species are interested in habitability for an assortment of reasons, political, financial, humanitarian and scientific. We want to understand how our own climate is changing. How we’ll live in the climate of the future and what we can do to stem the tide of what our carbon consumption causes.
There could be agendas to push for cleaner energy sources, or driving politicians towards climate change denial to maintain nefarious financial gain.
We also might need a new lilypad to jump to, assuming we can sort out the travel obstacles. The thing that interests me personally the most is, when can I see an alien?
The habitable zone, also known as the “Goldilocks Zone”, is the region around a star where the average temperature on a planet allows for liquid water with which to make porridge. It’s that liquid water that we hunt for not only for our future uses, but as an indicator of where alien life could be in the Universe.
Problems outside this range are pretty obvious. Too hot, it’s a perpetual steam bath, or it produces separate piles of hydrogen and oxygen. Then your oxygen combines with carbon to form carbon dioxide, and then hydrogen just buggers off into space.
This is what happened with Venus. If the planet’s too cold, then bodies of water are solid skating rinks. There could be pockets of liquid water deep beneath the icy surface, but overall, they’re bad places to live.
We’ve got this on Mars and the moons of Jupiter and Saturn. The habitable zone is a rough measurement. It’s a place where liquid water might exist.
“The Chemistry of the Solar System” by Compound Interest’s Andy Brunning
Unfortunately, it’s not just a simple equation of the distance to the star versus the amount of energy output. The atmosphere of the planet matters a lot. In fact, both Venus and Mars are considered to be within the Solar System’s habitable zone.
Venusian atmosphere is so thick with carbon dioxide that it traps energy from the Sun and creates an inhospitable oven of heat that would quickboil any life faster than you can say “pass the garlic butter”.
It’s the opposite on Mars. The thin atmosphere won’t trap any heat at all, so the planet is bun-chillingly cold. Upgrade the atmospheres of either planet and you could get worlds which would be perfectly reasonable to live on. Maybe if we could bash them together and we could spill the atmosphere of one onto the other? Tell Blackbolt to ring up Franklin Richards, I have an idea!
When we look at other worlds in the Milky Way and wonder if they have life, it’s not enough to just check to see if they’re in the habitable zone. We need to know what shape their atmosphere is in.
Astronomers have actually discovered planets located in the habitable zones around other stars, but from what we can tell, they’re probably not places you’d want to live. They’re all orbiting red dwarf stars.
Artists impression of Gliese 581g. Credit: Lynette Cook/NSF
It doesn’t sound too bad to live in a red tinted landscape, provided it came with an Angelo Badalamenti soundtrack, red dwarf stars are extremely violent in their youth. They blast out enormous solar flares and coronal mass ejections. These would scour the surface of any planets caught orbiting them close enough for liquid water to be present.
There is some hope. After a few hundred million years of high activity, these red dwarf stars settle down and sip away at their fuel reserves of hydrogen for potentially trillions of years. If life can hold on long enough to get through the early stages, it might have a long existence ahead of it.
When you’re thinking about a new home among the stars, or trying to seek out new life in the Universe, look for planets in the habitable zone.
As we’ve seen, it’s only a rough guideline. You probably want to check out the place first and make sure it’s truly liveable before you commit to a timeshare condo around Gliese 581.
Do you think habitable planets are common in the Milky Way? Tell us what your perfect planet environment might be in the comments below.
Portrait of Galileo Galilei by Giusto Sustermans (1636). Credit: nmm.ac.uk
Galileo is considered one of the greatest astronomers of all time. His discovery of Jupiter’s major moons (Io, Europa, Ganymede and Callisto) revolutionized astronomy and helped speed the acceptance of the Copernican Model of the universe. However, Galileo is also known for the numerous scientific inventions he made during his lifetime.
These included his famous telescope, but also a series of devices that would have a profound impact on surveying, the use of artillery, the development of clocks, and meteorology. Galileo created many of these in order to earn extra money to support his family. But ultimately, they would help cement his reputation as the man who challenged centuries worth of previously-held notions and revolutionized the sciences.
Hydrostatic Balance:
Inspired by the story of Archimedes’ and his “Eureka” moment, Galileo began looking into how jewelers weighed precious metals in air, and then by displacement, to determine their specific gravity. In 1586, at the age of 22, he theorized of a better method, which he described in a treatise entitled La Bilancetta (or “The Little Balance”).
In this tract, he described an accurate balance for weighing things in air and water, in which the part of the arm on which the counter weight was hung was wrapped with metal wire. The amount by which the counterweight had to be moved when weighing in water could then be determined very accurately by counting the number of turns of the wire. In so doing, the proportion of metals like gold to silver in the object could be read off directly.
Galileo’s “La Billancetta”, in which he describes a new method of measuring the specific gravity of precious metals. Credit: Museo Galileo
Galileo’s Pump:
In 1592, Galileo was appointed professor of mathematics at the University of Padua and made frequent trips to the Arsenal – the inner harbor where Venetian ships were fitted out. The Arsenal had been a place of practical invention and innovation for centuries, and Galileo used the opportunity to study mechanical devices in detail.
In 1593, he was consulted on the placement of oars in galleys and submitted a report in which he treated the oar as a lever and correctly made the water the fulcrum. A year later the Venetian Senate awarded him a patent for a device for raising water that relied on a single horse for operation. This became the basis of modern pumps.
To some, Galileo’s Pump was a merely an improvement on the Archimedes Screw, which was first developed in the third century BCE and patented in the Venetian Republic in 1567. However, there is apparent evidence connecting Galileo’s invention to Archimedes earlier and less sophisticated design.
Pendulum Clock:
During the 16th century, Aristotelian physics was still the predominant way of explaining the behavior of bodies near the Earth. For example, it was believed that heavy bodies sought their natural place or rest – i.e at the center of things. As a result, no means existed to explain the behavior of pendulums, where a heavy body suspended from a rope would swing back and forth and not seek rest in the middle.
Spring driven pendulum clock, designed by Huygens, built by instrument maker Salomon Coster (1657),[96] and copy of the Horologium Oscillatorium,[97] Museum Boerhaave, Leiden.
Already, Galileo had conducted experiments that demonstrated that heavier bodies did not fall faster than lighter ones – another belief consistent with Aristotelian theory. In addition, he also demonstrated that objects thrown into the air travel in parabolic arcs. Based on this and his fascination with the back and forth motion of a suspended weight, he began to research pendulums in 1588.
In 1602, he explained his observations in a letter to a friend, in which he described the principle of isochronism. According to Galileo, this principle asserted that the time it takes for the pendulum to swing is not linked to the arc of the pendulum, but rather the pendulum’s length. Comparing two pendulum’s of similar length, Galileo demonstrated that they would swing at the same speed, despite being pulled at different lengths.
According to Vincenzo Vivian, one of Galileo’s contemporaries, it was in 1641 while under house arrest that Galileo created a design for a pendulum clock. Unfortunately, being blind at the time, he was unable to complete it before his death in 1642. As a result, Christiaan Huygens’ publication of Horologrium Oscillatoriumin 1657 is recognized as the first recorded proposal for a pendulum clock.
The Sector:
The cannon, which was first introduced to Europe in 1325, had become a mainstay of war by Galileo’s time. Having become more sophisticated and mobile, gunners needed instrumentation to help them coordinate and calculate their fire. As such, between 1595 and 1598, Galileo devised and improved a geometric and military compass for use by gunners and surveyors.
The Sector, a military/geometric compass designed by Galileo Galilei. Credit: chsi.harvard.edu
Existing gunner’s compasses relied on two arms at right angles and a circular scale with a plumb line to determine elevations. Meanwhile, mathematical compasses, or dividers, developed during this time were designed with various useful scales on their legs. Galileo combined the uses of both instruments, designing a compass or sector that had many useful scales engraved on its legs that could be used for a variety of purposes.
In addition to offering a new and safer way for gunners to elevate their cannons accurately, it also offered a quicker way of computing the amount of gunpowder needed based on the size and material of the cannonball. As a geometric instrument, it enabled the construction of any regular polygon, computation of the area of any polygon or circular sector, and a variety of other calculations.
Galileo’s Thermometer:
During the late 16th century, there existed no practical means for scientists to measure heat and temperature. Attempts to rectify this within the Venetian intelligentsia resulted in the thermoscope, an instrument that built on the idea of the expansion of air due to the presence of heat.
In ca. 1593, Galileo constructed his own version of a thermoscope that relied on the expansion and contraction of air in a bulb to move water in an attached tube. Over time, he and his colleagues worked to develop a numerical scale that would measure the heat based on the expansion of the water inside the tube.
Galileo Galilei’s telescope with his handwritten note specifying the magnifying power of the lens, at an exhibition at The Franklin Institute in Philadelphia. Credit: AP Photo/Matt Rourke
And while it would take another century before scientists – such as Daniel G. Fahrenheit and Anders Celsius – began developing universal temperature scales that could be used in such instrument, Galileo’s thermoscope was a major breakthrough. In addition to being able to measure heat in air, it also provided quantitative meteorological information for the first time ever.
Galileo’s Telescope:
While Galileo did not invent the telescope, he greatly improved upon them. Over the course of many months during 1609, he unveiled multiple telescope designs that would collectively come to be known as Galilean Telescopes. The first, which he constructed between June and July of 1609, was a three-powered spyglass, which he replaced by August with an eight-powered instrument that he presented to the Venetian Senate.
By the following October or November, he managed to improve upon this with the creation a twenty-powered telescope – the very telescope that he used to observe the Moon, discover the four satellites of Jupiter (thereafter known as the Galilean Moons), discern the phases of Venus, and resolve nebular patches into stars.
These discoveries helped Galileo to advance the Copernican Model, which essentially stated that the Sun (and not the Earth) was the center of the universe (aka. heliocentrism). He would go on to refine his designs further, eventually creating a telescope that could magnify objects by a factor of 30.
Though these telescopes were humble by modern standards, they were a vast improvement over the models that existed during Galileo’s time. The fact that he managed to construct them all himself is yet another reason why they are considered his most impressive inventions.
Because of the instruments he created and the discoveries they helped make, Galileo is rightly recognized as one of the most important figures of the Scientific Revolution. His many theoretical contributions to the fields of mathematics, engineering and physics also challenged Aristotelian theories that had been accepted for centuries.
In short, he was one of just a few people who – through their tireless pursuit of scientific truth – forever changed our understanding of the universe and the fundamental laws that govern it.
The symbols of the eight planets, and Pluto, Credit: insightastrology.net
In our long history of staring up at the stars, human beings have assigned various qualities, names, and symbols for all the objects they have found there. Determined to find patterns in the heavens that might shed light on life here on Earth, many of these designations also ascribed (and were based on) the observable behavior of the celestial bodies.
When it came to assigning signs to the planets, astrologists and astronomers – which were entwined disciplines in the past -made sure that these particular symbols were linked to the planets’ names or their history in some way.
Mercury:
This planet is named after the Roman god who was himself the messenger of the gods, noted for his speed and swiftness. The name was assigned to this body largely because it is the planet closest to the Sun, and which therefore has the fastest rotational period. Hence, the symbol is meant to represent Mercury’s helmet and caduceus – a herald’s staff with snakes and wings intertwined.
Mercury, as imaged by the MESSENGER spacecraft, which was named after the messenger of the gods because it has the fastest orbit around the Sun. Image Credit: NASA/JHU/Carnegie Institution.
Venus:
Venus’ symbol has more than one meaning. Not only is it the sign for “female”, but it also represents the goddess Venus’ hand mirror. This representation of femininity makes sense considering Venus was the goddess of love and beauty in the Roman Pantheon. The symbol is also the chemical sign for copper; since copper was used to make mirrors in ancient times.
Earth:
Earth’s sign also has a variety of meanings, although it does not refer to a mythological god. The most popular view is that the circle with a cross in the middle represents the four main compass points. It has also been interpreted as the Globus Cruciger, an old Christian symbol for Christ’s reign on Earth.
This symbol is not just limited to Christianity though, and has been used in various culture around the world. These include, but are not limited to, Norse mythology (where it appears as the Solar or Odin’s Cross), Native American cultures (where it typically represented the four spirits of direction and the four sacred elements), the Celtic Cross, the Greek Cross, and the Egyptian Ankh.
In fact, perhaps owing to the simplicity of the design, cross-shaped incisions have made appearances as petroglyphs in European cult caves dating all the way back to the beginning of the Upper Paleolithic, and throughout prehistory to the Iron Age.
Mars, as photographed with the Mars Global Surveyor, is identified with the Roman god of war. Credit: NASA
Mars:
Mars is named after the Roman god of war, owing perhaps to the planet’s reddish hue, which gives it the color of blood. For this reason, the symbol associated with Mars represents the god of wars’ shield and spear. Additionally, it is the same sign as the one used to represent “male”, and hence is associated with self-assertion, aggression, sexuality, energy, strength, ambition and impulsiveness.
Jupiter:
Jupiter’s sign, which looks like an ornate, oddly shaped “four,” also stands for a number of symbols. It has been said to represent an eagle, which was the Jovian god’s bird. Additionally, the symbol can stand for a “Z,” which is the first letter of Zeus – who was Jupiter’s Greek counterpart.
The line through the symbol is consistent with this, since it would indicate that it was an abbreviation for Zeus’ name. And last, but not least, there is the addition of the swirled line which is believed to represent a lighting bolt – which just happens to Jupiter’s (and Zeus’) weapon of choice.
Saturn:
Like Jupiter, Saturn resembles another recognizable character – this time, it’s an “h.” However, this symbol is actually supposed to represent Saturn’s scythe or sickle, because Saturn is named after the Roman god of agriculture (after the Greek god Cronus, leader of the Titans, who was also depicted as holding a scythe).
Jupiter, the largest planet in the Solar System, is appropriately named after the Roman father of the gods. Credit: NASA/ESA/A. Simon (Goddard Space Flight Center)
Uranus:
The sign for Uranus is a combination of two other signs – Mars’ sign and the symbol of the Sun – because the planet is connected to these two in mythology. Uranus represented heaven in Roman mythology, and this ancient civilization believed that the Sun’s light and Mars’ power ruled the heavens.
Neptune:
Neptune’s sign is linked to the sea god Neptune, who the planet was named after. Appropriately, the symbol represents this planet is in the shape of the sea god’s trident.
Pluto:
Although Pluto was demoted to a dwarf planet in 2006, it still retains its old symbol. Pluto’s sign is a combination of a “P” and a “L,” which are the first two letters in Pluto as well as the initials of Percival Lowell, the astronomer who discovered the planet.
A full Moon flyby, as seen from Paris, France. Credit and copyright: Sebastien Lebrigand.
Moon:
The Moon is represented by a crescent shape, which is a clear allusion to how the Moon appears in the night sky more often than not. Since the Moon is also tied to people’s perceptions, moods, and emotional make-up, the symbol has also come to represents the mind’s receptivity.
Sun:
And then there’s the Sun, which is represented by a circle with a dot in the middle. In the case of the Sun, this symbol represents the divine spirit (circle) surrounding the seed of potential, which is a direct association with ancient Sun worship and the central role the Sun gods played in their respective ancient pantheons.
A picture of Earth taken by Apollo 11 astronauts. Credit: NASA
With the end of World War II, the Allies and the Soviet Bloc found themselves locked in a state of anatgonism. As they poured over the remains of the Nazi war machine, they discovered incredible advances in rocketry and aerospace engineering, and began scrambling to procure all they could.
For many of the many decades that followed, this state would continue as both sides struggled to make advancements in the field of space exploration ahead of the other. This was what is popularly known as the “Space Age”, an era that was born of the advent of nuclear power, advances in rocketry, and the desire to be the first to put men into space and on the Moon.
![Spring driven pendulum clock, designed by Huygens, built by instrument maker Salomon Coster (1657),[96] and copy of the Horologium Oscillatorium,[97] Museum Boerhaave, Leiden](https://www.universetoday.com/wp-content/uploads/2008/11/Christiaan_Huygens_Clock_and_Horologii_Oscillatorii.jpg)
