A Recipe for Returning Pluto to Full Planethood

A storm is brewing, a battle of words and a war of the worlds. The Earth is not at risk. It is mostly a civil dispute, but it has the potential to influence the path of careers. In 2014, a Harvard led debate was undertaken on the question: Is Pluto a planet. The impact of the definition of planet and everything else is far reaching – to the ends of the Universe.

It could mean a count of trillions of planets in our galaxy alone or it means leaving the planet Pluto out of the count – designation, just a dwarf planet. This is a question of how to classify non-stellar objects. What is a planet, asteroid, comet, planetoid or dwarf planet? Does our Solar System have 8 planets or some other number? Even the count of planets in our Milky Way galaxy is at stake.

"Dawn arising." The latest image of Ceres - February 12, 2015 -  by the Dawn spacecraft from 80,000 km. With icy deposits pock marking its surface, a possible reservoir of water below its surface, is Ceres a planet, dwarf planet, an asteroid or all three? (Credit: NASA/Dawn)
“Dawn arising.” The latest image of Ceres – February 12, 2015 – by the Dawn spacecraft from 80,000 km. With icy deposits pock marking its surface, a possible reservoir of water below its surface, is Ceres a planet, dwarf planet, an asteroid or all three? (Credit: NASA/Dawn)

Not to dwell on the Harvard debate, let it be known that if given their way, the debates outcome would reset the Solar System to nine planets. For over eight years, the solar system has had eight planets. During the period  1807 to 1845, our Solar System had eleven planets. Neptune was discovered in 1846 and astronomers began to discover many more asteroids. They were eliminated from the club. This is very similar to what is now happening to Pluto-like objects – Plutoids. So from 1846 to 1930, there were 8 planets – the ones as defined today.

The discoverer of Pluto - Clyde Tombaugh in the 1930s and again with homebuilt telescope in the 1990s that earned him an assignment at Lowell Observatory - discover Planet X. Cremated remains of Clyde are attached to the New Horizons space probe now approaching the dwarf planet Pluto.
The discoverer of Pluto – Clyde Tombaugh in the 1930s and again with homebuilt telescope in the 1990s that earned him an assignment at Lowell Observatory – discover Planet X. The cremated remains of Clyde are attached to the New Horizons space probe that is now approaching the dwarf planet Pluto.

In 1930, a Kansas farm boy, Clyde Tombaugh, hired by Lowell Observatory discovered Pluto and for 76 years there were 9 planets. In the year 2006, the International Astronomical Union (IAU) took up a debate using a “democratic process” to accept a new definition of planet, define a new type – dwarf planet and then set everything else as “Small Bodies.” If your head is spinning with planets, you are not alone.

All two body systems have a barycenter, the shared point in space around which they orbit. Pluto and Charon’s happens to be between both bodies due to their proximity and similar mass. (Credit: NASA/New Horizons)

Two NASA missions were launched immediately before and after the IAU announcement took affect. The Dawn mission suddenly was to be launched to an asteroid and a dwarf planet and the New Horizons had rather embarked on a nine year journey to a planet belittled to a dwarf planet – Pluto. Principal Investigator, Dr. Alan Stern was upset. Furthermore, from the discoveries of the Kuiper mission and other discoveries, we now know that there are hundreds of billions of planets in our Milky Way galaxy; possibly trillions. The present definition excludes hundreds of billions of bodies from planethood status.

The presently known largest trans-Neptunian objects (TSO) - are likely to be surpassed by future discoveries. Which of these trans-Neptunian objects (TSO) would you call planets and which "dwarf planets"? (Illustration Credit: Larry McNish, Data: M.Brown)
The presently known largest trans-Neptunian objects (TSO) – are likely to be surpassed by future discoveries. Which of these trans-Neptunian objects (TSO) would you call planets and which “dwarf planets”? (Illustration Credit: Larry McNish, Data: M.Brown)

There are two main camps with de facto leaders. One camp has Dr. Mike Brown of Caltech and the other, Dr. Stern of the Southwest Research Institute (SWRI) as leading figures. A primary focus of Dr. Brown’s research is the study of trans-Neptunian objects while Dr. Sterns’s activities are many but specifically, the New Horizons mission which is 6 months away from its flyby of Pluto. Consider first the IAU Resolution 5A that its members approved:

(1) A “planet” is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighborhood around its orbit.

(2) A “dwarf planet” is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape2, (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.

(3) All other objects, except satellites, orbiting the Sun shall be referred to collectively as “Small Solar System Bodies”.

This is our starting point – planet, dwarf planet, everything else. Consider “everything else”. This broad category includes meteoroids, asteroids, comets and planetesimals. Perhaps other small body types will arise as we look more closely at the Universe. Within the category, there is now a question of what is an asteroid and what is a comet. NASA’s flybys of comets and now ESA’s Rosetta at 67P/Churyumov–Gerasimenko are making the delineation between the two types difficult. The difference between a meteoroid and an asteroid is simply defined as less than or greater than one meter in size, respectively. So the Chelyabinsk event absolutely involved a small asteroid – about 20 meters in diameter. Planetesimals are small bodies in a solar nebula that are the building blocks of planets but they could lead to the creation of all the other types of small bodies.

Dr. Alan Stern, project scientist for New Horizons and Neil deGrasse Tyson discuss the New Horizons spacecraft in the mission operations center at JHU/APL. The interview was for a NOVA special (12/14/2011), the Pluto Files, about a Kansas farm boy, a missing planet and the 70 years of astronomical discoveries leading to the present day. (Credit: JHU/APL,PBS)
Dr. Alan Stern, project scientist for New Horizons and Neil deGrasse Tyson discuss the New Horizons spacecraft in the mission operations center at JHU/APL. The interview was for a NOVA special (12/14/2011), the Pluto Files, about a Kansas farm boy, a missing planet and the 70 years of astronomical discoveries leading to the present day. (Credit: JHU/APL,PBS)

Putting aside the question of “Small Bodies” and its sub-classes, what should be the definition of planet and dwarf planet? These are the two terms that demoted Pluto and raised Ceres to dwarf planet. It is also interesting to note how Resolution 5A is meant exclusively for our Solar System. In 2006, there were not thousands of exo-planets but just a few dozen extreme cases but nevertheless, the IAU did not choose to extend the definition to “stars” but rather just in reference to our pretty well known star, the Sun.

Recall Tim Allen’s movie, “The Santa Clause”. Clauses can cause a heap of trouble. The IAU has such a clause – Clause C which has caused much of the present controversy around the definition of planets. Clause (c) of Resolution 5A: “has cleared the neighborhood around its orbit.” This is the Pluto killer-clause which demoted it to dwarf planet status and reduced the number of planets in our solar system to eight. In a sense, the IAU chose to cauterize a wound, a weakness in the definitions, that if left unchanged, would have led to who knows how many planets in our Solar System.

The question of what is Pluto is open for public discussion so armed with enough knowledge to be dangerous, the following is my proposed alternative to the IAU’s that are arguably an improvement. The present challenge to Pluto’s status lies in the Kuiper Belt and Oort Cloud. Such belts or clouds are probably not uncommon throughout the galaxy. Plutoids are the 500 lb gorilla in the room.

Two spacecraft, Dawn and New Horizon will reach their final objectives in 2015 - Dwarf Planets - Ceres and Pluto. (Credit: NASA, Illustration - T.Reyes)
Two spacecraft, Dawn and New Horizon will reach their final objectives in 2015 – Dwarf Planets – Ceres and Pluto. (Credit: NASA, Illustration – T.Reyes)

This year, as touted by the likes of Planetary Society, Universe Today and elsewhere, is the year of the dwarf planet. How remarkable and surprising will the study of Ceres, Pluto and Charon by NASA spacecraft be? There is a strong possibility that after the celestial dust clears and data analysis is published, the IAU will take on the challenge again to better define what is a planet and everything else. It is impossible to imagine that the definitions can remain unchanged for long. Even now, there is sufficient information to independently assess the definitions and weigh in on the approaching debate. Anyone or any group – from grade schools to astronomical societies – can take on the challenge.

To encourage a debate and educate the public on the incredible universe that space probes and advanced telescopes are revealing, what follows is one proposed solution to what is a planet and everything else.

planet: is a celestial body that a) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium – nearly round shape, b) has a differentiated interior as a result of its formation c) has insufficient mass to fuse hydrogen in its core, d) does not match the definition of a moon.

minor planet: is a planet with a mass less than one Pluto mass and does not match the definition of a moon.

inter-Stellar (minor) planet: is a (minor) planet that is not gravitationally bound to a stellar object.

binary (minor) planet: is a celestial body that is orbiting another (minor) planet for which the system’s barycenter resides above the surface of both bodies.

These definitions solve some hairy dilemmas. For one, planets orbit around the majority of most stars in the Universe, not just the Sun as Resolution 5A was only intended. Planets can also exist gravitationally not bound to a star –  the result of it own molecular cloud collapse without a star or expulsion from a stellar system. One could specify gravitational expulsion however, it is possible that explosive events occur that cause the disintegration of a star and its binding gravity or creates such an impulse that a planet is thrusted out of a stellar system. Having an atmosphere certainly doesn’t work. Astronomers are already anticipating Mars or Earth-sized objects deep in the Oort cloud that could have no atmosphere – frozen out and also despite their size, not be able to “clear their neighborhood.”

An animation (above) of Kepler mission planet candidates compiled by Jeff Thorpe. Kepler and other exoplanet projects are revealing that the properties of planets – orbits, size, temperature, makeup – are all extreme. Does Pluto represent one of those extremes – the smallest of planets? (Credit: NASA/Kepler, Jeff Thorp)

 

The need to create a lower-end limit to what is a planet reached a near fever pitch with the discovery of a Trans-Nepturnian Object (TNO) in 2005 that is bigger than Pluto – Eris.  Dr. Michael Brown of Caltech and his team led in the discovery of bright large KBOs. There was not just Eris but many of nearly the same size as Pluto. So without clause (c), one would be left with a definition for planet that could allow the count of planets in our Solar System to rise into the hundreds maybe even thousands. This would become a rather unmanageable problem; the number of planets rising year after year and never settled and with no means to make reasonable comparisons between planetary systems throughout our galaxy and even the Universe.

The book that tells the story of discovery - trans-Neptunian objects (TNO) that led to the downfall of Pluto from full planethood to that of a dwarf. The 2006 IAU decision was a pre-emptive strike to stave off a proliferation of planets in our system. It worked but "killed" Pluto. Did it have it coming? Dr. Brown also agrees that the present definition of planet is flawed and incomplete. (Photo Credits: Caltech/M.Brown)
The book that tells the story of discovery – trans-Neptunian objects (TNO) that led to the downfall of Pluto from full planethood to that of a dwarf. The 2006 IAU decision was a pre-emptive strike to stave off a proliferation of planets in our system. It worked but “killed” Pluto. Did it have it coming? Dr. Brown also agrees that the present definition of planet is flawed and incomplete. (Photo Credits: Caltech/M.Brown)

Two more celestial body types follow that are proposed to round out the set.

moon: is a celestial body that a) orbits a (minor) planet and b) for which the barycenter of its orbit is below the surface of its parent (minor) planet.

This creates the possibility of a planet-moon system such that its barycenter is above the surface of the larger body. Pluto and Charon are the most prominent case in our Solar System. In such cases, if one body meets the criteria of a (minor)planet, then the other body can also be assessed to determine if it is also a (minor) planet and the pair as binary (minor) planets. If the primary body was a minor planet, it is possible that the barycenter could be above its surface but the secondary body does not meet all the criteria of a minor planet, specifically “differentiated interior”.

The definition of moon is compounded by the existence of, for example, asteroids with moons. For such objects, the smaller object is defined as a satellite.

Satellite: is a celestial body that a) orbits another celestial body, b) whose parent body is not a (minor) planet.

Another permissible term is moonlet which could be used to describe both very small moons such as those found in the Jovian and Saturn systems or a small body orbiting an asteroid or comet. Moonlet could replace satellite.

The discriminator between planet and moon is not mass but simply whether the celestial body orbits a (minor) planet and the barycenter resides inside the larger body. The definition of moon excludes the possibility of a planet orbiting another planet except in the special case of binary (minor) planet.

Defining a lower size limit to “Planet” is necessary to compare stellar systems and classify. A limit based on the body’s average surface pressure and temperature or the surface gravity could define a limit. While they could, they are not practical because of the extremes and diverse combinations of conditions. Strange objects would fall through the cracks.

Removing clause (c) – “has cleared the neighborhood around its orbit” – will avoid a future conflict such as a very low mass star with a plutoid-sized object or smaller, in a close orbit that has cleared its neighborhood.

Additionally, choosing to declare that Pluto becomes the “standard weight” that differentiates minor planet from planet sets a precedent. In an era in which computers measure and tally the state of our existence, setting this limit to include Pluto and return it as the ninth planet of our Solar System, is, in a small but significant way, a re-declaration of our humanity. Soon we will be challenged by artificial intelligence greater than ours; we are already have. Where will we stand our ground?

Forget about Pluto for a moment. Should Eris be our tenth Planet? Like Pluto it has a prominent moon- Dysnomia. Human perception and conceptions of the Universe have shaped our view of the Solar System. The Ptolemaic system (Earth centered), Kepler's Harmonic Spheres, even the fact that ten digits reside on our hands impact our impression of the Solar System (Photo Credits:NASA/ESA and M. Brown / Caltech)
Forget about Pluto for a moment. Should Eris be our tenth planet? Like Pluto it has a prominent moon- Dysnomia. Human perception and conceptions of the Universe have shaped our view of the Solar System. The Ptolemaic system (Earth centered), Kepler’s Harmonic Spheres, even the fact that ten digits reside on our hands impact our impression of the Solar System (Photo Credits:NASA/ESA and M. Brown / Caltech)

The consequences of this proposed set of definitions, makes Ceres a minor planet and no longer an asteroid. Many trans-Neptunian objects discovered in this century become minor planets. Of the known TNOs only Pluto and Eris meets the criteria of planet.The dwarf planet Eris would become the tenth planet. Makemake, Sedna, Quaoar, Orcus, Haumea would be minor planets. By keeping Pluto a planet and defining it as the standard bearer, only one new planet must be declared. Surely, more will be found, very distant, in odd elliptical and tilted orbits. The count of planets in our solar system could rise by 10, 20 maybe 50 and perhaps this would make the definition untenable but maybe not. So be it. New Horizons will fly by a dwarf planet in July but this should mark the beginning of the end of the present set of definitions.

Three perspectives of a ten planet Solar System. No longer Earth centered, or with harmonic spheres but now with planets outside the ecliptic plane and growing. How many planets would be too many? (Credits: Wikimedia, T.Reyes)
Three perspectives of a ten planet Solar System. No longer Earth centered, or with harmonic spheres but now with planets outside the ecliptic plane and growing. How many planets would be too many? (Credits: Wikimedia, T.Reyes)

This set of definitions defines a set of celestial bodies that consistently covers the spectrum of known bodies. There is the potential of exotic celestial objects that are spawned from cataclysmic events or from the unique conditions during the early epochs of the Universe or from remnants of old or dying stellar objects. Their discovery will likely trigger new or revised definitions but these definitions are a good working set for the time being. Ultimately, it is the decision of the IAU but the sharing of knowledge and the democratic processes that we cherish permits anyone to question and evaluate such definitions or proclamations.To all that share an interest in Pluto as or as not a planet raise your hand and be heard.

A video from 2014 by Kurz Gesagt describing the Pluto-Charon system. Is this a binary planet system or one of the “dwarf” variety?

Further Reading

Learn All About Pluto, The Most Famous Dwarf Planet, E. Howell, Universe Today, 1/17/2015

A synopsis of Pluto facts and figures at Universe Today, compendium of pages on Pluto

What is the Kuiper Belt?, video, Universe Today, 12/30/2013, Fraser Cain asks Mike Brown to explain the Kuiper Belt

Is The Moon A Planet?, E. Howell, Universe Today, 1/27/2015

It Looks Like These Are All the Bright Kuiper Belt Objects We’ll Ever FindUniverse Today, 1/12/2015

2015, NASA’s Year of the Dwarf Planet, Universe Today, 12/14/2014

A Serendipitous All Sky Survey For Bright Objects In The Outer Solar SystemCornell University Library, 1/5/2015

Ten Years of Eris, at Mike Brown’s Planets, 1/5/2015

My condolences to the friends and family of Tammy Plotner, the first regular contributing writer to Universe Today. Can’t we all relate to what drew Tammy to write about the Universe? She wrote outstanding articles for U.T.

me_and_the_dob

A Star Passed Through the Solar System Just 70,000 Years Ago

Astronomers have reported the discovery of a star that passed within the outer reaches of our Solar System just 70,000 years ago, when early humans were beginning to take a foothold here on Earth. The stellar flyby was likely close enough to have influenced the orbits of comets in the outer Oort Cloud, but Neandertals and Cro Magnons – our early ancestors – were not in danger. But now astronomers are ready to look for more stars like this one.

A comparison of the Solar System and its Oort Cloud. 70,000 years ago, Scholz's Star and companion passed along the outer boundaries of our Solar System (Credit: NASA, Michael Osadciw/University of Rochester)
A comparison of the Solar System and its Oort Cloud. 70,000 years ago, Scholz’s Star and companion passed along the outer boundaries of our Solar System (Credit: NASA, Michael Osadciw/University of Rochester, Illustration-T.Reyes)

Lead author Eric Mamajek from the University of Rochester and collaborators report in The Closest Known Flyby Of A Star To The Solar System (published in Astrophysical Journal on February 12, 2015) that “the flyby of this system likely caused negligible impact on the flux of long-period comets, the recent discovery of this binary highlights that dynamically important Oort Cloud perturbers may be lurking among nearby stars.”

The star, named Scholz’s star, was just 8/10ths of a light year at closest approach to the Sun. In comparison, the nearest known star to the Sun is Proxima Centauri at 4.2 light years.

While the internet has been rife with threads and accusations of a Nemesis star that is approaching the inner Solar System and is somehow being “hidden” by NASA, this small red dwarf star with a companion represents the real thing.

In 1984, the paleontologists David Raup and Jack Sepkoski postulated that a dim dwarf star, now widely known on the internet as the Nemesis Star, was in a very long period Solar orbit. The elliptical orbit brought the proposed star into the inner Solar System every 26 million years, causing a rain of comets and mass extinctions on that time period. By no coincidence, because of the sheer numbers of red dwarfs throughout the galaxy, Scholz’s star nearly fits such a scenario. Nemesis was proposed to be in a orbit extending 95,000 A.U. compared to Scholz’s nearest flyby distance of 50,000 A.U. Recent studies of impact rates on Earth, the Moon and Mars have discounted the existence of a Nemesis star (see New Impact Rate Count Lays Nemesis Theory to Rest, Universe Today, 8/1/2011)

But Scholz’s star — a real-life Oort Cloud perturber — was a small red dwarf star star with a M9 spectral classification. M-class stars are the most common star in our galaxy and likely the whole Universe, as 75% of all stars are of this type. Scholz’s is just 15% of the mass of our Sun. Furthermore, Scholz’s is a binary star system with the secondary being a brown dwarf of class T5. Brown Dwarfs are believed to be plentiful in the Universe but due to their very low intrinsic brightness, they are very difficult to discover … except, as in this case, as companions to brighter stars.

The astronomers reported that their survey of new astrometric data of nearby stars identified Scholz’s as an object of interest. The star’s transverse velocity was very low, that is, the stars sideways motion. Additionally, they recognized that its radial velocity – motion towards or away from us, was quite high. For Scholz’s, the star was speeding directly away from our Solar System. How close could Scholz’s star have been to our system in the past? They needed more accurate data.

The collaborators turned to two large telescopes in the southern hemisphere. Spectrographs were employed on the Southern African Large Telescope (SALT) in South Africa and the Magellan telescope at Las Campanas Observatory, Chile. With more accurate trangental and radial velocities, the researchers were able to calculate the trajectory, accounting for the Sun’s and Scholz’s motion around the Milky Way galaxy.

Scholz’s star is an active star and the researchers added that while it was nearby, it shined at a dimly of about 11th magnitude but eruptions and flares on its surface could have raised its brightness to visible levels and could have been seen as a “new” star by primitive humans of the time.

The relative sizes of the inner Solar System, Kuiper Belt and the Oort Cloud. (Credit: NASA, William Crochot)
The relative sizes of the inner Solar System, Kuiper Belt and the Oort Cloud. (Credit: NASA, William Crochot)

At present, Scholz’s star is 20 light years away, one of the 70 closest stars to our Solar System. However, the astronomers calculated, with a 98% certainty, that Scholz’s passed within 0.5 light years, approximately 50,000 Astronomical Units (A.U.) of the Sun.

An A.U. is the mean distance from the Earth to the Sun and 50,000 is an important mile marker in our Solar System. It is the outer reaches of the Oort Cloud where billions of comets reside in cold storage, in orbits that take hundreds of thousands of years to circle the Sun.

With this first extraordinary close encounter discovered, the collaborators of this paper as well as other researchers are planning new searches for “Nemesis” type stars. The Large Synoptic Survey Telescope (LSST) and other telescopes within the next decade will bring an incredible array of data sets that will uncover many more red dwarf, brown dwarf and possibly orphan planets roaming in nearby space. Some of these could likewise be traced to past or future near misses to the Sun and Earth system.

Astronomers are Predicting at Least Two More Large Planets in the Solar System

Could there be another Pluto-like object out in the far reaches of the Solar System? How about two or more?

Earlier this week, we discussed a recent paper from planet-hunter Mike Brown, who said that while there aren’t likely to be any bright, easy-to-find objects, there could be dark ones “lurking far away.” Now, a group of astronomers from the UK and Spain maintain at least two planets must exist beyond Neptune and Pluto in order to explain the orbital behavior of objects that are even farther out, called extreme trans-Neptunian objects (ETNO).

The presently known largest small bodies in the Kuiper Belt are likely not to be surpassed by any future discoveries. This is the conclusion of Dr. Michael Brown, et al. (Illustration Credit: Larry McNish, Data: M.Brown)
The presently known largest small bodies in the Kuiper Belt are likely not to be surpassed by any future discoveries. This is the conclusion of Dr. Michael Brown, et al. (Illustration Credit: Larry McNish, Data: M.Brown)

We do know that Pluto shares its region Solar System with more than 1500 other tiny, icy worlds along with likely countless smaller and darker ones that have not yet been detected.

In two new paper published this week, scientists at the Complutense University of Madrid and the University of Cambridge noted that the most accepted theory of trans-Neptunian objects is that they should orbit at a distance of about 150 AU, be in an orbital plane – or inclination – similar to the planets in our Solar System, and they should be randomly distributed.

But that differs from what is actually observed. What astronomers see are groupings of objects with widely disperse distances (between 150 AU and 525 AU) and orbital inclinations that vary between 0 to 20 degrees.

“This excess of objects with unexpected orbital parameters makes us believe that some invisible forces are altering the distribution of the orbital elements of the ETNO,” said Carlos de la Fuente Marcos, scientist at UCM and co-author of the study, “ and we consider that the most probable explanation is that other unknown planets exist beyond Neptune and Pluto.”

He added that the exact number is uncertain, but given the limited data that is available, their calculations suggest “there are at least two planets, and probably more, within the confines of our solar system.”

In their studies, the team analyzed the effects of what is called the ‘Kozai mechanism,’ which is related to the gravitational perturbation that a large body exerts on the orbit of another much smaller and further away object. They looked at how the highly eccentric comet 96P/Machholz1 is influenced by Jupiter (it will come near the orbit of Mercury in 2017, but it travels as much as 6 AU at aphelion) and it may “provide the key to explain the puzzling clustering of orbits around argument of perihelion close to 0° recently found for the population of ETNOs,” the team wrote in one of their papers.

The discovery images of 2012 VP113. Each one was taken about two hours apart on Nov. 5, 2012. Behind the object, you can see background stars and galaxies that remained still (from Earth's perspective) in the picture frame. Credit: Scott S. Sheppard: Carnegie Institution for Science
The discovery images of 2012 VP113. Each one was taken about two hours apart on Nov. 5, 2012. Behind the object, you can see background stars and galaxies that remained still (from Earth’s perspective) in the picture frame. Credit: Scott S. Sheppard: Carnegie Institution for Science

They also looked at the dwarf planet discovered last year called 2012 VP113 in the Oort cloud (its closest approach to the Sun is about 80 astronomical units) and how some researchers say it appears its orbit might be influenced by the possible presence of a dark and icy super-Earth, up to ten times larger than our planet.

“This Sedna-like object has the most distant perihelion of any known minor planet and the value of its argument of perihelion is close to 0°,” the team writes in their second paper. “This property appears to be shared by almost all known asteroids with semimajor axis greater than 150 au and perihelion greater than 30 au (the extreme trans-Neptunian objects or ETNOs), and this fact has been interpreted as evidence for the existence of a super-Earth at 250 au. In this scenario, a population of stable asteroids may be shepherded by a distant, undiscovered planet larger than the Earth that keeps the value of their argument of perihelion librating around 0° as a result of the Kozai mechanism.”

Of course, the theory put forth in two papers published by the team goes against the predictions of current models on the formation of the Solar System, which state that there are no other planets moving in circular orbits beyond Neptune.

But the team pointed to the recent discovery of a planet-forming disk around the star HL Tauri that lies more than 100 astronomical units from the star. HL Tauri is more massive and younger than our Sun and the discovery suggests that planets can form several hundred astronomical units away from the center of the system.

The team based their analysis by studying 13 different objects, so what is needed is more observations of the outer regions of our Solar System to determine what might be hiding out there.

Further reading:
Carlos de la Fuente Marcos, Raúl de la Fuente Marcos, Sverre J. Aarseth. “Flipping minor bodies: what comet 96P/Machholz 1 can tell us about the orbital evolution of extreme trans-Neptunian objects and the production of near-Earth objects on retrograde orbits”. Monthly Notices of the Royal Astronomical Society 446(2):1867-1873, 2015.

C. de la Fuente Marcos, R. de la Fuente Marcos. “Extreme trans-Neptunian objects and the Kozai mechanism: signalling the presence of trans-Plutonian planets? Monthly Notices of the Royal Astronomical Society Letters 443(1): L59-L63, 2014.

SiNC press release

The Dark Energy Survey Begins to Reveal Previously Unknown Trans-Neptunian Objects

Sometimes when you stare at something long enough, you begin to see things. This is not the case with optical sensors and telescopes. Sure, there is noise from electronics, but it’s random and traceable. Stargazing with a telescope and camera is ideal for staring at the same patches of real estate for very long and repeated periods. This is the method used by the Dark Energy Survey (DES), and with less than one percent of the target area surveyed, astronomers are already discovering previously unknown objects in the outer Solar System.

The Dark Energy Survey is a five year collaborative effort that is observing Supernovae to better understand the structures and expansion of the universe. But in the meantime, transient objects much nearer to home are passing through the fields of view. Trans-Neptunian Objects (TNOs), small icy worlds beyond the planet Neptune, are being discovered. A new scientific paper, released as part of this year’s American Astronomical Society gathering in Seattle, Washington, discusses these newly discovered TNOs. The lead authors are two undergraduate students from Carleton College of Northfield, Minnesota, participating in a University of Michigan program.

The Palomar Sky Survey (POSS-1, POSS-2), the Sloan Digital Sky Survey, and every other sky survey have mapped not just the static, nearly unchanging night sky, but also transient events such as passing asteroids, comets, or novae events. The Dark Energy Survey is looking at the night sky for structures and expansion of the Universe. As part of the five year survey, DES is observing ten select 3 square degree fields for Type 1a supernovae on a weekly basis. As the survey proceeds, they are getting more than anticipated. The survey is revealing more trans-Neptunian objects. Once again, deep sky surveys are revealing more about our local environment – objects in the farther reaches of our Solar System.

DES is an optical imaging survey in search of Supernovae that can be used as weather vanes to measure the expansion of the universe. This expansion is dependent on the interaction of matter and the more elusive exotic materials of our Universe – Dark Energy and Dark Matter. The five year survey is necessary to achieve a level of temporal detail and a sufficient number of supernovae events from which to draw conclusions.

In the mean time, the young researchers of Carleton College – Ross Jennings and Zhilu Zhang – are discovering the transients inside our Solar System. Led by Professor David Gerdes of the University of Michigan, the researchers started with a list of nearly 100,000 observations of individual transients. Differencing software and trajectory analysis helped identify those objects that were trans-Neptunian rather than asteroids of the inner Solar System.

While asteroids residing in the inner solar system will pass quickly through such small fields, trans-Neptunian objects (TNOs) orbit the Sun much more slowly. For example, Pluto, at an approximate distance of 40 A.U. from the Sun, along with the object Eris, presently the largest of the TNOs, has an apparent motion of about 27 arc seconds per day – although for a half year, the Earth’s orbital motion slows and retrogrades Pluto’s apparent motion. The 27 arc seconds is approximately 1/60th the width of a full Moon. So, from one night to the next, TNOs can travel as much as 100 pixels across the field of view of the DES survey detectors since each pixel has a width of 0.27 arc seconds.

Composite Dark Energy Camera image of one of the sky regions that the collaboration will use to study supernovae, exploding stars that will help uncover the nature of dark energy. The outlines of each of the 62 charge-coupled devices can be seen. This picture spans 2 degrees across on the sky and contains 520 megapixels. (Credit: Fermilab)
Composite Dark Energy Camera image of one of the sky regions that the collaboration will use to study supernovae, exploding stars that will help uncover the nature of dark energy. The outlines of each of the 62 charge-coupled devices can be seen. This picture spans 2 degrees across on the sky and contains 520 megapixels. (Credit: Fermilab)

The scientific sensor array, DECam, is located at Cerro Tololo Inter-American Observatory (CTIO) in Chile utilizing the 4-meter (13 feet) diameter Victor M. Blanco Telescope. It is an array of 62 2048×4096 pixel back-illuminated CCDs totaling 520 megapixels, and altogether the camera weighs 20 tons.

A simple plot of the orbit of one of sixteen TNOs discovered by DES observatrions. (Credit: Dark Energy Detectives)
A simple plot of the orbit of one of sixteen TNOs discovered by DES observations. (Credit: Dark Energy Detectives)

With a little over 2 years of observations, the young astronomers stated, “Our analysis revealed sixteen previously unknown outer solar system objects, including one Neptune Trojan, several objects in mean motion resonances with Neptune, and a distant scattered disk object whose 1200-year orbital period is among the 50 longest known.”

Object 2013 TV158 is one of the objects discovered by Carleton College and University of Michigan team. Observed more than a dozen times over 10 months, the animated gif shows two image frames from August, 2014 taken two hours apart. 2013 TV158 takes 1200 years to orbit the Sun and is likely a few hundred kilometers across (about the size of the Grand Canyon. (Credit: Dark Energy Detectives)
Object 2013 TV158 is one of the objects discovered by the Carleton College and University of Michigan team. Observed more than a dozen times over 10 months, the animated gif shows two image frames from August 2014 taken two hours apart. 2013 TV158 takes 1200 years to orbit the Sun and is likely a few hundred kilometers across – about the size of the Grand Canyon. (Credit: Dark Energy Detectives)

“So far we’ve examined less than one percent of the area that DES will eventually cover,” says Dr. Gerdes. “No other survey has searched for TNOs with this combination of area and depth. We could discover something really unusual.”

Illustration of colour distribution of the trans-Neptunian objects. The horizontal axis represents the difference in intensity between visual (green & yellow) and blue of the object while the vertical is the difference between visual and red. The distribution indicates how TNOs share a common origin and physical makeup as well as common weathering in space. Yellow objects serve as reference: Neptune's moon Triton, Saturn's moon Phoebe, centaur Pholus, and the planet Mars. The objects color represents the hue of the object. The size of the objects are relative where the larger objects are more accurate estimates and smaller objects are simply based on absolute magnitude. (Credit: Wikimedia, Eurocommuter)
Illustration of color distribution of the trans-Neptunian objects. The horizontal axis represents the difference in intensity between visual (green & yellow) and blue of the object, while the vertical axis is the difference between visual and red. The distribution indicates how TNOs share a common origin and physical makeup, as well as common weathering in space. Yellow objects serve as reference: Neptune’s moon Triton, Saturn’s moon Phoebe, centaur Pholus, and the planet Mars. The object’s color represents the hue of the object. The size of the objects are relative – the larger objects are more accurate estimates, while smaller objects are simply based on absolute magnitude. (Credit: Wikimedia, Eurocommuter)

What does it all mean? It is further confirmation that the outer Solar System is chock-full of rocky-icy small bodies. There are other examples of recent discoveries, such as the search for a TNO for the New Horizons mission. As New Horizons has been approaching Pluto, the team turned to the Hubble space telescope to find a TNO to flyby after the dwarf planet. Hubble made short shrift of the work, finding three that the probe could reach. However, the demand for Hubble time does not allow long term searches for TNOs. A survey such as DES will serve to uncover many thousands of more objects in the outer Solar System. As Dr. Michael Brown of Caltech has stated, there is a fair likelihood that a Mars or Earth-sized object will be discovered beyond Neptune in the Oort Cloud.

References:
Observation of new trans-Neptunian Objects in the Dark Energy Survey Supernova Fields
Undergraduate Researchers Discover New Trans-Neptunian Objects
Dark Sky Detectives

For more details on the Dark Energy Survey: DES Website

Weekly Space Hangout – Nov. 21, 2014: New Images of Europa

Host: Fraser Cain (@fcain)

Guests:
Morgan Rehnberg (cosmicchatter.org / @cosmic_chatter)
Brian Koberlein (@briankoberlein)
Ramin Skibba (@raminskibba)
Dave Dickinson (@astroguyz / www.astroguyz.com)

Continue reading “Weekly Space Hangout – Nov. 21, 2014: New Images of Europa”

‘Naked’ Comets Could Expose Solar System’s Ancient Origin Story

What’s a comet that doesn’t look like a comet? The question sounds contradictory, but astronomers believe these objects exist. As comets pass through the solar system, they bleed ice and dust as the Sun’s effects wash over their small bodies. Over time, some of the objects can keep going like ghost ships — just without the ices that used to produce a show.

There already is a class of objects called damocloids that are believed to be extinct comets, but scientists believe they have found something new with two mysterious visitors — what they call “naked” comets — from the outer Solar System.

The two objects originate from an area that astronomers term the Oort Cloud, a hypothetical collection of icy bodies that orbit as far away as 100,000 times the Earth-Sun distance (astronomical unit). Gravitational influences then kick the objects in towards the Sun and they commence orbits that can last millions of years.

When Jan Oort first proposed this concept in the 1950s, he said that some of the objects there could have only a tiny layer of ice that would immediately evaporate during the first pass in near the Sun. That’s what astronomers think they are seeing in objects C/2013 P2 Pan-STARRS and C/2014 S3 Pan-STARRS.

The familiar solar system with its 8 planets occupies a tiny space inside a large spherical shell containing trillions of comets - the Oort Cloud. Credit: Wikimedia Commons
The familiar solar system with its 8 planets occupies a tiny space inside a large spherical shell containing trillions of comets – the Oort Cloud. Credit: Wikimedia Commons

“Objects on long-period orbits like this usually exhibit cometary tails, for example Comet ISON and Comet Hale Bopp, so we immediately knew this object was unusual,” stated Karen Meech, an astronomer at the University of Hawaii at Manoa who led the research. “I wondered if this could be the first evidence of movement of solar system building blocks from the inner solar system to the Oort Cloud.”

The automated Pan STARRS1 survey telescope found C/2013 P2 in August 2013, with astronomers remarking its orbit resembled that of a comet. But, C/2013 P2’s surface was quiet. A second look the next month with the 8-meter Gemini North telescope in Hawaii revealed a little bit of light and a dusty tail. The object stayed at about the same brightness, even when it got to its closest approach to the Sun (2.8 AU) in February 2014.

After the comet swung around the Sun and telescopes could look at it again, examinations with the Gemini North telescope found something weird: the object’s spectrum looked red. This makes it look more like a Kuiper Belt object — something that roams in shallower waters in the Solar System, beyond Neptune’s orbit — than a typical comet or asteroid.

While results were still being analyzed, in September a NASA survey found an object with curiously similar properties: C/2014 S3. When it was found, the object had already passed its closest approach to the Sun in August. But from analyzing the orbit, the scientists saw it had come to only within 2 AU. Also, the first observations showed barely a tail at all.

Distribution of Kuiper belt objects (green), along with various other outer Solar System bodies, based on data from the Minor Planet Center. [Credit:  Minor Planet Center; Murray and Dermott]
Distribution of Kuiper belt objects (green), along with various other outer Solar System bodies, based on data from the Minor Planet Center. [Credit: Minor Planet Center; Murray and Dermott]
A closer examination with the Canada-France-Hawaii Telescope revealed a mystery: the spectrum was more blue than red, hinting at materials similar to what you would find in the inner Solar System. The team says this could be a new class of objects altogether.

“I’ll be thrilled if this object turns out to have a surface composition similar to asteroids in the inner part of the asteroid belt.  If this is the case, it will be remarkable for a body found so far out in the Solar System,” stated Meech.

“There are several models that try to explain how the planets grew in the early Solar System, and some of these predict that material formed close to the sun could have been thrown outward into the outer Solar System and Oort Cloud, where it remains today. Maybe we are finally seeing that evidence.”

Results were presented today (Nov. 10) at the Division of Planetary Sciences meeting of the American Astronomical Society in Tucson, Arizona. A press release did not say if the research is peer-reviewed, or state publication plans.

Source: University of Hawaii Institute for Astronomy

A Compendium of Universe Today Comet Siding Spring Articles: January 2013 – October 2014

We present here a compendium of Universe Today articles on comet Siding Spring. Altogether 18 Universe Today stories and counting have represented our on-going coverage of a once in a lifetime event. The articles beginning in February 2013, just days after its discovery, lead to the comet’s penultimate event – the flyby of Mars, October 19, 2014. While comet Siding Spring will reach perihelion just 6 days later, October 25, 2014, it will hardly have sensed the true power and impact that our Sun can have on a comet.

Siding Spring’s Oort Cloud cousin, Comet ISON in November 2013 encountered the Sun at a mere 1.86 million km. The intensity of the Sun’s glare was 12,600 times greater than what Siding Spring will experience in a few days. Comet ISON did not survive its passage around the Sun but Comet Siding Spring will soon turn back and begin a very long journey to its place of origin, the Oort Cloud far beyond Pluto.

An animation of comet Siding Springs passage through the inner Solar System. The scale size of its place of origin would dwarf the orbits of the Solar System to little more than a small dot. (Illustration Credit: Near-Earth Object (NEO) office, NASA/JPL)
An animation of comet Siding Springs passage through the inner Solar System. The scale size of its place of origin would dwarf the orbits of the Solar System to little more than a small dot. (Illustration Credit: Near-Earth Object (NEO) office, NASA/JPL)

The closest approach for comet Siding Spring with the Sun – perihelion is at a distance of 1.39875 Astronomical Units (1 AU being the distance between the Earth and Sun), still 209 million km (130 million miles). The exact period of the comet is not exactly known but it is measured in millions of years. In my childhood astronomy book, it stated that comet Halley, when it is at its furthest distance from the Sun, is moving no faster than a galloping horse. This has also been all that comet Siding Spring could muster for millions of years – the slightest of movement in the direction of the Sun.

It is only in the last 3 years, out all the millions spent on its journey, that it has felt the heat of the Sun and been in proximity to the  planetary bodies of our Solar System. This is story of all long period comets. A video camera on Siding Spring would have recorded the emergence and evolution of one primate out of several, one that left the trees to stand on two legs, whose brain grew in size and complexity and has achieved all the technological wonders (and horrors) we know of today.

Now with its close encounter with Mars, the planet’s gravity will bend the trajectory of the comet and reduce its orbital period to approximately one million years. No one will be waiting up late for its next return to the inner Solar System.

It is also unknown what force in the depths of the Oort cloud nudged the comet into its encounter with Mars and the Sun. Like the millions of other Oort cloud objects, Siding Spring has spent its existence – 4.5 Billion years, in the darkness of deep space, with its parent star, the Sun, nothing more than a point of light, the brightest star in its sky. The gravitational force that nudged it may have been a passing star, another cometary body or possibly a larger trans-Neptunian object the size of Pluto and even as large as Mars or the Earth.

The forces of nature on Earth cause a constant turning over geological features. Our oceans and atmosphere are constantly recycling water and gases. The comets that we receive from the Oort Cloud are objects as old as our Solar System. Yet it is the close encounter with Mars that has raised the specter of an otherwise small ordinary comet. All these comets from deep space are fascinating gems nearly unaltered for 1/3rd of the time span of the known Universe.

Universe Today’s Siding Spring Compendium

2014/10/17: Here’s A Look At Comet Siding Spring Two Days Before Its Encounter With Mars

2014/10/17: Weekly Space Hangout Oct 17 2014

2014/10/15: Comet A1 Siding Spring vs Mars Views In Space And Time

2014/10/10: How To See Comet Siding Spring As It Encounters Mars

2014/10/08: Comet Siding Spring Close Call For Mars Wake Up Call For Earth

2014/09/19: How NASA’s Next Mars Spacecraft Will Greet The Red Planet On Sunday

2014/09/09: Tales Tails Of Three Comets

2014/09/05: Maven Mars Orbiter Ideally Poised To Uniquely Map Comet Siding Spring Composition Exclusive Interview With Principal Investigator Bruce Jakosky

2014/08/30: Caterpillar Comet Poses For Pictures En Route To Mars

2014/07/26: NASA Preps For Nail Biting Comet Flyby Of Mars

2014/05/08: Interesting Prospects For Comet A1 Siding Spring Versus The Martian Atmosphere

2014/03/27: Mars Bound Comet Siding Spring Sprouts Multiple Jets

2014/01/29: Neowise Spots Mars Crossing Comet

2014/01/02: Comets Prospects For 2014 A Look Into The Crystal Ball

2013/04/12: New Calculations Effectively Rule Out Comet Impacting Mars In 2014

2013/03/28: NASA Scientists Discuss Potential Comet Impact On Mars

2013/03/05: Update On The Comet That Might Hit Mars

2013/02/26: Is A Comet On A Collision Course With Mars

PanSTARRS K1, the Comet that Keeps Going and Going and Going

Thank you K1 PanSTARRS for hanging in there!  Some comets crumble and fade away. Others linger a few months and move on. But after looping across the night sky for more than a year, this one is nowhere near quitting. Matter of fact, the best is yet to come.

This new visitor from the Oort Cloud making its first passage through the inner solar system, C/2012 K1 was discovered in May 2012 by the Pan-STARRS 1 survey telescope atop Mt. Haleakala in Hawaii at magnitude 19.7. Faint! On its the inbound journey from the Oort Cloud, C/2012 K1 approached with an orbit estimated in the millions of years. Perturbed by its interactions with the planets, its new orbit has been reduced to a mere  ~400,000 years.  That makes the many observing opportunities PanSTARRS K1 has provided that much more appreciated. No one alive now will ever see the comet again once this performance is over.

Comet C/2012 K1 PanSTARRS' changing appearance over the past year. Credit upper left clockwise: Carl Hergenrother, Damian Peach, Chris Schur and Rolando Ligustri
Comet C/2012 K1 PanSTARRS’ changing appearance over the past year. Credit upper left clockwise: Carl Hergenrother, Damian Peach, Chris Schur and Rolando Ligustri

Many amateur astronomers first picked up the comet’s trail in the spring of 2013 when it had brightened to around magnitude 13.5. My observing notes from June 2, 2013, read:

“Very small, about 20 arc seconds in diameter. Pretty faint at ~13.5 and moderately condensed but not too difficult at 142x . Well placed in Hercules.” Let’s just say it was a faint, fuzzy blob.

K1 PanSTARRS slowly brightened in Serpens last fall until it was lost in evening twilight. Come January this year it returned to the morning sky a little closer to Earth and Sun and a magnitude brighter. As winter snow gave way to frogs and flowers, the comet rocketed across Corona Borealis, Bootes and Ursa Major. Its fat, well-condensed coma towed a pair of tails and grew bright enough to spot in binoculars at magnitude 8.5 in late May.

Skywatchers can find C/2012 K1 PanSTARRS in the morning just in Hydra-Puppis just before dawn. The map shows its location daily with stars to magnitude 8.5. The numbers next to some stars are standard Flamsteed atllas catalog numbers. Source: Chris Marriott's SkyMap
Skywatchers can find C/2012 K1 PanSTARRS in the morning sky in the Hydra and Puppis just before dawn when it’s highest in the southeastern sky. The map shows its location daily with stars to magnitude 8.5. The numbers next to some stars are standard Flamsteed atlas catalog numbers. Click for a larger version. Source: Chris Marriott’s SkyMap

By July, it hid away in the solar glare a second time only to come back swinging in September’s pre-dawn sky.  Now in the constellation Hydra and even closer to Earth, C/2012 K1 has further brightened to magnitude 7.5. Though low in the southeast at dawn, I was pleasantly surprised to see it several mornings ago. Through my 15-inch (37-cm) reflector at 64x I saw a fluffy, bright coma punctuated by a brighter, not-quite-stellar nucleus and a faint tail extending 1/4º to the northeast.

Mid-northern observers can watch the comet’s antics through mid-October. From then on, K1 will only be accessible from the far southern U.S. and points south as it makes the rounds of Pictor, Dorado and Horologium. After all this time you might think the comet is ready to depart Earth’s vicinity. Not even. C/2012 K1 will finally make its closest approach to our planet on Halloween (88.6 million miles – 143 million km) when it could easily shine at magnitude 6.5, making it very nearly a naked-eye comet.

PanSTARRS K1’s not giving up anytime soon. Southern skywatchers will keep it in view through the spring of 2015 before it returns to the deep chill from whence it came. After delighting skywatchers for nearly two years, it’ll be hard to let this one go.

MAVEN Mars Orbiter Ideally Poised to Uniquely Map Comet Siding Spring Composition – Exclusive Interview with Principal Investigator Bruce Jakosky

MAVEN to conduct up close observations of Comet Siding Spring during Oct. 2014
MAVEN is NASA’s next Mars Orbiter and will investigate how the planet lost most of its atmosphere and water over time. Credit: NASA
Story updated[/caption]

NASA’s MAVEN Mars Orbiter is “ideally” instrumented to uniquely “map the composition of Comet Siding Spring” in great detail when it streaks past the Red Planet during an extremely close flyby on Oct. 19, 2014 – thereby providing a totally “unexpected science opportunity … and a before and after look at Mars atmosphere,” Prof. Bruce Jakosky, MAVEN’s Principal Investigator of CU-Boulder, CO, told Universe Today in an exclusive interview.

The probes state-of-the-art ultraviolet spectrograph will be the key instrument making the one-of-a-kind compositional observations of this Oort cloud comet making its first passage through the inner solar system on its millions year orbital journey.

“MAVEN’s Imaging Ultraviolet Spectrograph (IUVS) is the ideal way to observe the comet coma and tail,” Jakosky explained.

“The IUVS can do spectroscopy that will allow derivation of compositional information.”

“It will do imaging of the entire coma and tail, allowing mapping of composition.”

Comet: Siding Spring. The images above show -- before and after filtering -- comet C/2013 A1, also known as Siding Spring, as captured by Wide Field Camera 3 on NASA's Hubble Space Telescope.  Image Credit: NASA, ESA, and J.-Y. Li (Planetary Science Institute)
Comet: Siding Spring
The images above show — before and after filtering — comet C/2013 A1, also known as Siding Spring, as captured by Wide Field Camera 3 on NASA’s Hubble Space Telescope. Image Credit: NASA, ESA, and J.-Y. Li (Planetary Science Institute)

Moreover the UV spectrometer is the only one of its kind amongst NASA’s trio of Martian orbiters making its investigations completely unique.

“IUVS is the only ultraviolet spectrometer that will be observing the comet close up, and that gives the detailed compositional information,” Jakosky elaborated

And MAVEN, or the Mars Atmosphere and Volatile Evolution, is arriving just in the nick of time to fortuitously capture this fantastically rich data set of a pristine remnant from the solar system’s formation.

The spacecraft reaches Mars in less than 15 days. It will rendezvous with the Red Planet on Sept. 21 after a 10 month interplanetary journey from Earth.

Furthermore, since MAVEN’s purpose is the first ever detailed study of Mars upper atmosphere, it will get a before and after look at atmospheric changes.

“We’ll take advantage of this unexpected science opportunity to make observations both of the comet and of the Mars upper atmosphere before and after the comet passage – to look for any changes,” Jakosky stated.

How do MAVEN’s observations compare to NASA’s other orbiters Mars Odyssey (MO) and Mars Reconnaissance Orbiter (MRO), I asked?

“The data from the other orbiters will be complementary to the data from IUVS.”

“Visible light imaging from the other orbiters provides data on the structure of dust in the coma and tail. And infrared imaging provides information on the dust size distribution.”

IUVS is one of MAVENS’s nine science sensors in three instrument suites targeted to study why and exactly when did Mars undergo the radical climatic transformation.

How long will MAVEN make observations of Comet C/2013 A1 Siding Spring?

“We’ll be using IUVS to look at the comet itself, about 2 days before comet nucleus closest approach.”

“In addition, for about two days before and two days after nucleus closest approach, we’ll be using one of our “canned” sequences to observe the upper atmosphere and solar-wind interactions.”

“This will give us a detailed look at the upper atmosphere both before and after the comet, allowing us to look for differences.”

Describe the risk that Comet Siding Spring poses to MAVEN, and the timing?

“We have the encounter with Comet Siding Spring about 2/3 of the way through the commissioning phase we call transition.”

“We think that the risk to the spacecraft from comet dust is minimal, but we’ll be taking steps to reduce the risk even further so that we can move on toward our science mission.”

“Throughout this entire period, though, spacecraft and instrument health and safety come first.”

This graphic depicts the orbit of comet C/2013 A1 Siding Spring as it swings around the sun in 2014. On Oct. 19, 2014 the comet will have a very close pass at Mars. Its nucleus will miss Mars by about 82,000 miles (132,000 kilometers).   Credit: NASA/JPL-Caltech
This graphic depicts the orbit of comet C/2013 A1 Siding Spring as it swings around the sun in 2014. On Oct. 19, 2014 the comet will have a very close pass at Mars. Its nucleus will miss Mars by about 82,000 miles (132,000 kilometers). Credit: NASA/JPL-Caltech

What’s your overall hope and expectation from the comet encounter?

“Together [with the other orbiters], I’m hoping it will all provide quite a data set!

“From Mars, the comet truly will fill the sky!” Jakosky gushed.

The comet’s nucleus will fly by Mars at a distance of only about 82,000 miles (132,000 kilometers) at 2:28 p.m. ET (18:28 GMT) on Oct. 19, 2014. That’s barely 1/3 the distance from the Earth to the Moon.

What’s the spacecraft status today?

“Everything is on track.”

Maven spacecraft trajectory to Mars. Credit: NASA
Maven spacecraft trajectory to Mars on Sept. 4, 2014. Credit: NASA

The $671 Million MAVEN spacecraft’s goal is to study Mars upper atmosphere to explore how the Red Planet lost most of its atmosphere and water over billions of years and the transition from its ancient, water-covered past, to the cold, dry, dusty world that it has become today.

MAVEN soared to space over nine months ago on Nov. 18, 2013 following a flawless blastoff from Cape Canaveral Air Force Station’s Space Launch Complex 41 atop a powerful Atlas V rocket and thus began a 10 month interplanetary voyage from Earth to the Red Planet.

It is streaking to Mars along with ISRO’s MOM orbiter, which arrives a few days later on September 24, 2014.

So far it has traveled 95% of the distance to the Red Planet, amounting to over 678,070,879 km (421,332,902 mi).

As of Sept. 4, MAVEN was 205,304,736 km (127,570,449 miles) from Earth and 4,705,429 km (2,923,818 mi) from Mars. Its Earth-centered velocity is 27.95 km/s (17.37 mi/s or 62,532 mph) and Sun-centered velocity is 22.29 km/s (13.58 mi/s or 48,892 mph) as it moves on its heliocentric arc around the Sun.

One-way light time from MAVEN to Earth is 11 minutes and 24 seconds.

MAVEN is NASA’s next Mars orbiter and launched on Nov. 18, 2014 from Cape Canaveral, Florida. It will study the evolution of the Red Planet’s atmosphere and climate. Universe Today visited MAVEN inside the clean room at the Kennedy Space Center. With solar panels unfurled, this is exactly how MAVEN looks when flying through space and circling Mars and observing Comet Siding Spring. Credit: Ken Kremer/kenkremer.com
MAVEN is NASA’s next Mars orbiter and launched on Nov. 18, 2014 from Cape Canaveral, Florida. It will study the evolution of the Red Planet’s atmosphere and climate. Universe Today visited MAVEN inside the clean room at the Kennedy Space Center. With solar panels unfurled, this is exactly how MAVEN looks when flying through space and circling Mars and observing Comet Siding Spring. Credit: Ken Kremer/kenkremer.com

Stay tuned here for Ken’s continuing MAVEN, MOM, Rosetta, Opportunity, Curiosity, Mars rover and more Earth and planetary science and human spaceflight news.

Ken Kremer

NASA’s Mars bound MAVEN spacecraft launches atop Atlas V booster at 1:28 p.m. EST from Space Launch Complex 41 at Cape Canaveral Air Force Station on Nov. 18, 2013. Image taken from the roof of the Vehicle Assembly Building (VAB) at NASA’s Kennedy Space Center.  Credit: Ken Kremer/kenkremer.com
NASA’s Mars bound MAVEN spacecraft launches atop Atlas V booster at 1:28 p.m. EST from Space Launch Complex 41 at Cape Canaveral Air Force Station on Nov. 18, 2013. Image taken from the roof of the Vehicle Assembly Building (VAB) at NASA’s Kennedy Space Center. Credit: Ken Kremer/kenkremer.com
NASA’s MAVEN Mars orbiter, chief scientist Prof. Bruce Jakosky of CU-Boulder and Ken Kremer of Universe Today inside the clean room at the Kennedy Space Center on Sept. 27, 2013. MAVEN launches to Mars on Nov. 18, 2013 from Florida. Credit: Ken Kremer/kenkremer.com
NASA’s MAVEN Mars orbiter, chief scientist Prof. Bruce Jakosky of CU-Boulder and Ken Kremer of Universe Today inside the clean room at the Kennedy Space Center on Sept. 27, 2013. MAVEN launched to Mars on Nov. 18, 2013 from Florida. Credit: Ken Kremer/kenkremer.com

How Can We Move the Earth?

Sooner or later we’re going to want to move the Earth further away from the Sun. It turns out, there are a few techniques that might actually make this possible. Not easy, but possible.

You live here. I live here. Everybody lives here. For now.

In 500 million years the gradual heating of the Sun will burn away all life on Earth. Then we might have to move. Even if we get past the 500 million year deadline, the Sun will die as a red giant in about 5 billion years.

Let’s review our options? We could die… orrrr we could move the Earth. Just like any other mad science scheme, there’s a hundred ways to skin this cat. We could launch powerful rockets off the Earth, which would push the Earth a little bit in the opposite direction.

We could build a giant teleporter and disassemble the Earth atom by atom into a new location. We could repeatedly smash things into the Earth. Eventually knocking it off orbit, possibly also changing its axis and or rotation.

We could paint half the Earth silver, stop it rotating and let the Sun push it away. We could dig a giant hole down to the core and repeatedly detonate warheads inside the Earth forcing molten material to fly off into space, propelling us forwards like a deflating balloon.

Sure, maybe that does all sound a little crazy. We could build a gravity tug, and slowly pull the Earth away from the Sun. What’s a gravity tug? I’m so glad you asked.

You could build a solar sail with a huge mass connected to it. This gigantic weight would want to fall towards the Earth, and the Earth slowly drifts towards the weight. The solar sail is being pushed away by the Sun dragging both the weight and as a result the Earth along with it. This would take a very, very, very long time.

The Solar Sail demonstration mission.  Credit: NASA
The Solar Sail demonstration mission. Credit: NASA

Here’s the best idea scientists have come up with so far. Gravity assists: Attach rockets to an asteroid, comet or Kuiper belt object and have it fall on a trajectory that takes it close to the Earth. Earth and this space rock would exchange a little momentum.

The rock slows down a bit and goes into a new orbit, and the Earth speeds up a little. That additional momentum pushes our orbit up a tiny little bit, and now we’re further away from the Sun. You’d need to do this tens of thousands or even a million times.

You might think, “Hey, that’s crazy. Where would you get all this stuff to hurl past the Earth?”. Don’t worry, the Oort cloud alone has billions of objects with a total of 30 times the mass of the Earth.

To prepare for Roastpocalypse, If we started now, we should cause a close pass with a large object every few thousand years. We bring them within 10,000 km of the surface of the Earth, which would have the likely side effect of causing severe tides and storms.

The layout of the solar system, including the Oort Cloud, on a logarithmic scale. Credit: NASA
The layout of the solar system, including the Oort Cloud, on a logarithmic scale. Credit: NASA

Oh, and get the math wrong and you’ll smash an asteroid into the Earth. Just so you know, these would be way bigger than the object that killed the dinosaurs. One hit from a 100km diameter object would sterilize the biosphere.

If we pushed the Earth out to about 1.5 times its current orbit, which might get a little too cozy with Mars for comfort, we’d give the Earth another 5 billion years of habitability,

Then the Sun turns into a red giant, and then dies as a white dwarf. And nothing can help us then… except perhaps some kind of planet sized star gate.

What do you think? What’s the best suggestion you’ve got to move the Earth out to a safe distance? Tell us in the comments below.