Thursday, October 23, 2014

Stunning View of Solar Systems Largest Volcano and Valles Marineris Revealed by India’s Mars Orbiter Mission

Stunning View of Solar Systems Largest Volcano and Valles Marineris Revealed by India’s Mars Orbiter Mission:

Olympus Mons, Tharsis Bulge and Valles Marineris from from ISRO's Mars Orbiter Mission. Credit: ISRO


Olympus Mons, Tharsis Bulge trio of volcanoes, and Valles Marineris from ISRO’s Mars Orbiter Mission. Note the clouds and south polar ice cap. Credit: ISRO
India’s Mars Orbiter Mission (MOM) has delivered another sweet treat – a stunning view of our Solar System’s largest volcano and the largest canyon.

Just days ago, MOM captured a new global image of the Red Planet dominated by Olympus Mons and Valles Marineris – which is the largest known volcano and the largest known canyon in the Solar System, respectively.

Situated right in between lies a vast volcanic plateau holding a trio of huge volcanoes comprising the Tharsis Bulge: Arsia Mons, Pavonis Mons, and Ascraeus Mons. All four volcanoes are shield volcanoes.

To give an idea of its enormity, Olympus Mons stands about three times taller than Mount Everest and is about the size of Arizona.

Olympus Mons from Mars orbit compared to the state of Arizona. Credit: NASA


Olympus Mons from Mars orbit compared to the state of Arizona. Credit: NASA
Olympus Mons is located in Mars’ western hemisphere and measures 624 kilometers (374 miles) in diameter, 25 km (16 mi) high, and is rimmed by a 6 km (4 mi) high scarp.

Valles Marineris is often called the “Grand Canyon of Mars.” It spans about as wide as the entire United States.

The Indian Space Research Organization (ISRO), India’s space agency which designed and developed the orbiter released the image on Oct. 17, barely two days ahead of the planet’s and spacecrafts’ extremely close encounter with comet Siding Spring.

By the way, a relieved ISRO tweeted MOM’s survival of her close shave with the once-in-a-lifetime cometary passage with gusto, soon after the swingby:

“Phew! Experience of a lifetime. Watched the #MarsComet #SidingSpring whizzing past the planet. I’m in my orbit, safe and sound.”

The new global image was taken by the tri-color camera as MOM swooped around the Red Planet in a highly elliptical orbit whose nearest point to Mars (periapsis) is at 421.7 km and farthest point (apoapsis) at 76,993.6 km, according to ISRO.

To date ISRO has released four global images of the Red Planet, including a 3-D view, reported here.

Olympus Mons, the Tharsis Bulge, and Valles Marineris are near the equator.

Valles Marineris stretches over 4,000 km (2,500 mi) across the Red Planet, is as much as 600 km wide, and measures as much as 7 kilometers (4 mi) deep.

Here’s a comparison view of the region taken by NASA’s Viking 1 orbiter in the 1970s.

Global Mosaic of Mars Centered on Valles Marineris


Global Mosaic of Mars Centered on Valles Marineris from NASA’s Viking 1 orbiter. Credit: NASA
MOM is India’s first deep space voyager to explore beyond the confines of her home planet’s influence and successfully arrived at the Red Planet only one month ago after the “history creating” orbital insertion maneuver on Sept. 23/24 following a ten month journey.

The $73 million MOM mission is expected to last at least six months.

MOM’s success follows closely on the heels of NASA’s MAVEN orbiter which also successfully achieved orbit barely two days earlier on Sept. 21 and could last 10 years or more.

With MOM’s arrival, India became the newest member of an elite club of only four entities that have launched probes that successfully investigated Mars – following the Soviet Union, the United States, and the European Space Agency (ESA).

Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.

Ken Kremer

ISRO's Mars Orbiter Mission captures spectacular portrait of the Red Planet and swirling dust storms with the on-board Mars Color Camera from an altitude of 74500 km on Sept. 28, 2014. Credit: ISRO


ISRO’s Mars Orbiter Mission captures spectacular portrait of the Red Planet and swirling dust storms with the on-board Mars Color Camera from an altitude of 74,500 km on Sept. 28, 2014. Credit: ISRO


About 

Dr. Ken Kremer is a speaker, scientist, freelance science journalist (Princeton, NJ) and photographer whose articles, space exploration images and Mars mosaics have appeared in magazines, books, websites and calanders including Astronomy Picture of the Day, NBC, BBC, SPACE.com, Spaceflight Now and the covers of Aviation Week & Space Technology, Spaceflight and the Explorers Club magazines. Ken has presented at numerous educational institutions, civic & religious organizations, museums and astronomy clubs. Ken has reported first hand from the Kennedy Space Center, Cape Canaveral and NASA Wallops on over 40 launches including 8 shuttle launches. He lectures on both Human and Robotic spaceflight - www.kenkremer.com. Follow Ken on Facebook and Twitter
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No, This Is Not a Photo of India on Diwali

No, This Is Not a Photo of India on Diwali:

Yes, it's India, but it's not a photo captured from space during Diwali night. (Credit: NASA)


Yes, it’s India, but it’s not a photo captured from space during Diwali night. (Credit: NOAA)
Diwali, the Indian festival of lights, falls on Thursday, Oct. 23 this year and with it come celebrations, gift-giving, and brilliant lighting and firework displays all across the subcontinent of India… but this isn’t a picture of that. What is it exactly? Find out below…

Over the past several years this image has repeatedly resurfaced online, especially around the time of Diwali. And understandably so: it’s a beautiful view of India seemingly decorated for the festival… one can easily imagine the entire country awash in colorful lights from shore to shore.

But it’s not a photo at all, or even a singular image. Rather it’s a composite of many images acquired from a USAF Defense Meteorological Satellite Program (DMSP) satellite over the course of several years, and assembled by NOAA scientist Chris Elvidge to show the country’s growing population and urban areas.

In a 2012 article by Robert Johnson on Business Insider a NASA spokesperson described the colors in the image: “The white lights were the only illumination visible before 1992. The blue lights appeared in 1992. The green lights in 1998. And the red lights appeared in 2003.”

So what does India look like at night during the five-day-long Diwali festival? Click here and see.

While city lighting in India is definitely visible from space, it’s not the rainbow explosion of neon colors that Internet hoaxers and uninformed online enthusiasts would eagerly have you believe. According to Adam Voiland on the NASA Earth Observatory site, “in reality, any extra light produced during Diwali is so subtle that it is likely imperceptible when observed from space.”

So this year, don’t fall for any false descriptions of this picture… and, Happy Diwali!

Sources: Business Insider, Mashable, NASA Earth Observatory, EarthSky. Read more about the 2014 celebration of Diwali here.

HT to Peter Caltner on Twitter for re-alerting me of this.



About 

A graphic designer in Rhode Island, Jason writes about space exploration on his blog Lights In The Dark, Discovery News, and, of course, here on Universe Today. Ad astra!
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X-Ray Telescope Cracks Open Archives, Comes Up With Gassy Black Hole Gem

X-Ray Telescope Cracks Open Archives, Comes Up With Gassy Black Hole Gem:

by Elizabeth Howell on October 22, 2014
Six images that combine Chandra data with those from other telescopes. Credit: X-ray: NASA/CXC/SAO, Optical: NASA/STScI, Radio: NSF/NRAO/VLA).


Six images that combine Chandra data with those from other telescopes. Credit: X-ray: NASA/CXC/SAO, Optical: NASA/STScI, Radio: NSF/NRAO/VLA).
What a gem! This huge black hole in the middle of Hercules A is making gas around it super-heated to millions of degrees, making it shine brightly in X-Rays. The Chandra X-Ray Telescope captured the scene and in a new data release this week, telescope officials cracked open the archives to give us gems such as this.

The release comes as a part of American Archives Month, where every year Chandra officials go through the archives and pull out old Chandra data, combining it with the work of other telescopes to get as much information as possible about the objects being studied.

Chandra is one of three NASA “Great Observatories” still active, with the other two being the Hubble Space Telescope and the Spitzer Space Telescope. It’s been in operation now for more than 15 years.

You can see the six new pictures below. To read more about each of these objects, head on over to this link.

Six photos released from the Chandra X-Ray Observatory's archive in October 2014. Credit: NASA/CXC/SAO


Six photos released from the Chandra X-Ray Observatory’s archive in October 2014. Credit: NASA/CXC/SAO


About 

Elizabeth Howell is the senior writer at Universe Today. She also works for Space.com, Space Exploration Network, the NASA Lunar Science Institute, NASA Astrobiology Magazine and LiveScience, among others. Career highlights include watching three shuttle launches, and going on a two-week simulated Mars expedition in rural Utah. You can follow her on Twitter @howellspace or contact her at her website.
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Beastly Sunspot Amazes, Heightens Eclipse Excitement

Beastly Sunspot Amazes, Heightens Eclipse Excitement:

Ron Cottrell captured the sunspot group 2192 in all its swirly magnetic goodness in hydrogen-alpha light on October 19. To appreciate its size, he included the Earth (lower left) for reference. Credit: Ron Cottrell


Ron Cottrell captured the sunspot group 2192 in all its swirly magnetic goodness in hydrogen-alpha light on October 19. To appreciate its size, he included the Earth (lower left) for reference. Credit: Ron Cottrell
That’s one big, black blemish on the Sun today! Rarely have we been witness to such an enormous sunspot. Lifting the #14 welder’s glass to my eyes this morning I about jumped back and bumped into the garage.

Properly shielded, it was very easy to see with the naked eye. Unlike some other naked eye sunspots, this one showed structure. The eastern end was darker, the western half grayer and more extended.


Watch the giant spot rotate into view and grow right before your eyes in this 72-hour time-lapse video taken by SOHO’s HMI imager Oct. 18-20, 2014

Through a small telescope, the mix of dark umbras scattered amid weirdly sculpted penumbral “islands” was incredible to see. Photographs like the one above are wonderful documents, but witnessing this beautiful complex magnetic mess with your own eyes is another experience altogether. Region 2192 continues to grow and size and complexity and is now the largest sunspot group of solar cycle 24 which began in 2009 – more than five years ago!

Active region 2192 is now the largest sunspot group to appear in over five years. Credit: Alex Young


Active region 2192 is now the largest sunspot group to appear in over five years. Compare to Jupiter and the Earth. Credit: SDO/HMI/Alex Young
Every sunspot marks a region on the Sun’s shiny outer skin called the photosphere where magnetic energy is concentrated. Strong magnetic fields within a sunspot group quell the turbulent churning of the photosphere, chilling the region by several thousand degrees. Sunspots appear dark against the Sun’s blazing disk because they’re cooler. Cooler meaning 8,000 F instead of 11,000 F, so yes, they’re still VERY hot.


Watch as Region 2192 crackles with energy and flares as seen in far ultraviolet light with NASA’s Solar Dynamics Observatory.

Energy stored in sunspots’ twisted magnetic fields can suddenly be released in violent, explosions called solar flares. Billions of tons of solar plasma – the sizzling mix of protons and electrons that composes the Sun – are heated to millions of degrees during the explosion and rapidly accelerated into space. Radiation from radio waves to X-rays and gamma rays fans out at the speed of light. Fortunately for us, our atmosphere and planetary magnetic field protect us from most of what flares can fling our way.

NASA's Solar Dynamics Observatory took this photo of the sun and Jupiter-sized sunspot 2192 this morning Oct. 22 at 8:45 a.m. CDT. The view in a small telescope equipped with a safe solar filter is even better! Credit: NASA


NASA’s Solar Dynamics Observatory took this photo of the Sun and Jupiter-sized sunspot region 2192 this morning Oct. 22 at 8:45 a.m. CDT. The view in a small telescope equipped with a safe solar filter is even better! Credit: NASA
But as the Sun rotates this monster into our line of sight, possibilities for Earth-directed flares and coronal mass ejections increase as do geomagnetic storms, the bringer of auroras. Already in the past 48 hours, the spot has dished out seven M-class flares and a powerful X-1 flare even before it has fully come into view.  There’s more to come – Region 2192 harbors an unstable beta-gamma-delta magnetic field ripe for additional flaring including more of the X-class variety.

The sun on October 21 showing smaller sunspot regions along with our featured group. Credit: Sarah and Simon Fisher


The Sun on October 21 showing smaller sunspot regions along with our featured group. Credit: Sarah and Simon Fisher
There’s no doubt now that this behemoth will stick around to add a whole new dimension to tomorrow’s partial solar eclipse. I can’t wait to see the Moon’s black curve approach and at least partially occult the group from view. If you’re interested in getting some one-of-a-kind pictures of the scene, please see our own Dave Dickinson’s excellent guide on photographing the partial eclipse.

A sliver of a Moon rises in morning twilight today October 22 just a day away from its appointment with the Sun. Credit: Bob King


A sliver of a Moon rises in morning twilight today October 22 just a day away from its appointment with the Sun. Credit: Bob King
While we’re on the Moon, early morning risers had the pleasure of its company just one day before New Moon and solar eclipse. I was out watching the Orionid meteor shower. While not rich like the Perseids or Geminids I managed to catch a few including a few lucky shots with the camera.

An Orionid meteor slashes across the top of the frame directly above the constellation Orion early this morning October 22, 2014. Details: 24mm lens, f/2.8, 30-seconds at ISO 1600. Credit: Bob King


An Orionid meteor slashes across the top of the frame directly above the constellation Orion early this morning October 22, 2014. Details: 24mm lens, f/2.8, 30-seconds at ISO 1600. Credit: Bob King
The shower has peaked but will still be active the remainder of the week if you’re inclined to take a look. And I can’t resist. How about one last sweet close-up photo of sunspot group 2192? I have a feeling you won’t mind.

Monster Sunspot AR12192 taken by Karzaman Ahmad on October 21, 2014 from Langkawi Nagtional Observatory, Malaysia credit: Karzaman Ahmad and shared at spaceweather.com


Monster Sunspot AR12192 taken by Karzaman Ahmad on October 21, 2014, from Langkawi Nagtional Observatory, Malaysia. Credit: Karzaman Ahmad and shared at spaceweather.com. Click the image to see additional animations and photos on Alex Young’s site


About 

I'm a long-time amateur astronomer and member of the American Association of Variable Star Observers (AAVSO). My observing passions include everything from auroras to Z Cam stars. Every day the universe offers up something both beautiful and thought-provoking. I also write a daily astronomy blog called Astro Bob.
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Is Dark Matter Coming From The Sun?

Is Dark Matter Coming From The Sun?:

A huge filament erupts from the Sun in 2012. Credit: NASA Goddard Space Flight Center


A huge filament erupts from the Sun in 2012. Credit: NASA Goddard Space Flight Center
For decades, astronomers and cosmologists have postulated that the Universe is filled with an invisible, mysterious mass known as “dark matter.” For decades, the search for this elusive matter has dominated the field of cosmology. Precise measurements were obtained over 20 years ago when dark matter was first mapped in galaxy halos. Only recently has the existence of dark matter over much larger scales than even galaxy clusters been detected.

Recently, a group of physicists analyzed over 12 years’ worth of telescope data, and have found a signal that some think could be the first detection of a source of dark matter.

And it appears to be coming from … our Sun.

Distribution of dark matter when the Universe was about 3 billion years old, obtained from a numerical simulation of galaxy formation. The left panel displays the continuous distribution of dark matter particles, showing the typical wispy structure of the cosmic web, with a network of sheets and filaments, while the right panel highlights the dark matter halos representing the most efficient cosmic sites for the formation of star-bursting galaxies with a minimum dark matter halo mass of 300 billion times that of the Sun. Credit: VIRGO Consortium/Alexandre Amblard/ESA


Distribution of dark matter when the Universe was about 3 billion years old, obtained from a numerical simulation of galaxy formation. Credit: VIRGO Consortium/Alexandre Amblard/ESA
Using information obtained from the European Space Agency observatory, astronomers from the University of Leicester found variations in a stream of X-rays emanating from the Sun that match what would be expected if axions – a hypothetical dark-matter particle – were interacting with Earth’s magnetic field. If confirmed, the axion finding would be a huge discovery.

Axions were originally proposed to explain an anomaly in a different area of physics – the theory of the strong nuclear force, one of the four fundamental forces of nature. These uncharged, very light particles would be created in the Sun’s core and would barely interact with ordinary matter, which would allow them to zip through thousands of kilometers of solar plasma and escape into outer space.

But the axions that interacted with magnetic fields, such as the one that surrounds Earth, would be expected to turn into X-ray photons. Those photons are the particles the researchers say they may have seen.

The team found that as the European space telescope XMM-Newton (also called the X-ray Multi-Mirror Mission) passed through the strong magnetic field on the Sun-side of Earth, it saw a slightly more intense X-ray signal than when it was on the far side of Earth. Discounting known sources of X-rays, the background signal should be the same wherever the spacecraft is, according to the Leicester team.

In their 67-page paper, which was submitted in March of this year and appeared in this month’s issue of Monthly Notices of the Royal Astronomical Society, the researchers did their best to rule out more mundane phenomena – such as interaction between the solar wind and Earth’s magnetic field – before invoking axions as a source.

Axions interacting with Earth's magnetic field to form x-rays. Credit: University of Leicester


Axions interacting with Earth’s magnetic field to form x-rays, as detected by the ESA’s XMM-Newton probe. Credit: University of Leicester
One unusual aspect of this analysis is that it shows XMM-Newton picking up the X-ray photons, even though it is not looking straight into the Sun but at a right angle to it. This is odd because the photons are generally expected to continue in the same direction as the axions they were created from.

But the authors say that the axions could be scattered and end up in the telescope. The authors also show that hints of a similar signal can be found in data produced by NASA’s Chandra X-Ray Observatory, although a formal corroboration will take more data and years of analysis.

The concept of dark matter was first proposed by Jan Oort in 1932 to account for the orbital velocities of stars in the Milky Way, and then again by Fritz Zwicky in 1933 to account for evidence of “missing mass” in the orbital velocities of galaxies in clusters.

Dark matter has been widely studied, but much like the Higgs Boson, its existence was inferred despite a lack of direct evidence simply because it accounted for discrepancies in the observable data. According to consensus among cosmologists, dark matter could be composed primarily of a not yet characterized type of subatomic particle.

The leader of this most recent study, George Fraser  – an astronomer at the University of Leicester, UK – died just two days after he and his co-authors submitted the paper for publication. According to Andy Lawrence, an astronomer at the Institute for Astronomy in Edinburgh, UK, the study was Fraser’s “most astonishing swan song”.

Mike Watson, another astronomer at the University of Leicester (but who was not involved in the study), says that Fraser was an “exceptional scientist” and the mastermind behind the work. Even so, he expressed some skepticism towards the findings.

“The interpretation is quite appealing,” he said, “and on the human side of this is that we would all like it to be right, as it would be a great tribute to George. But that’s not how you do science.”

In addition, Fraser’s research team are not yet celebrating the publication of their findings, as there appears to be some anomalies in the data that has even them concerned.

“We found an unusual result that we can’t explain by any conventional method, and this axion theory does explain it,” said the study’s co-author Andy Read. “But it is just a hypothesis, and most hypotheses don’t make it.”

Others within the astronomical community are also not convinced that the axion interpretation is correct. Astronomer Peter Coles of the University of Sussex, UK, called the evidence “circumstantial.” In a post on his blog, “In the Dark”, he wrote, “It’s tantalising, but if you want to ask me where I’d put my money I’m afraid I’d probably go for messy local plasma physics rather than anything more fundamental.”

Still, the theory has its share of potential supporters. One such person is Igor Garcia Irastorza, who works on the CERN Axion Solar Telescope (CAST), based at the CERN physics laboratory near Geneva, Switzerland. He expressed that the idea was intriguing, but the kind of axion that would fit such a signal would clash with other astrophysical observations. And, as he said, the particles’ properties would have to be different than what has been theorized for decades.

Corroborating the Leicester findings will take cross-checks from other axion experiments that work in completely different ways to the telescopes, adds Konstantin Zioutas, who leads the CAST experiment. Only time will tell if a source of dark matter has been found, or if this is merely a hiccup in the ongoing search.

Further Reading: MNRAS
University of Leicester press release.



About 

Author, freelance writer, educator, Taekwon-Do instructor, and loving hubby, son and Island boy!
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Questioning the Impact Theory: What Really Killed the Dinosaurs?

Questioning the Impact Theory: What Really Killed the Dinosaurs?:

Which is the main culprit for the terminal Cretaceous extinction: the Chicxulub impact or Deccan Traps volcanism? Upper Image: Donald Davis, NASA JPL Lower Image: USGS


Which is the main culprit for the terminal Cretaceous extinction: the Chicxulub impact or Deccan Traps volcanism? Upper Image: Donald Davis, NASA JPL
Lower Image: USGS
About sixty five and a half million years ago, the Earth suffered its largest known cosmic impact. An asteroid or comet nucleus about 10 km in diameter slammed into what is now the Yucatan peninsula of Mexico. It gouged out a crater 180 to 200 km in diameter: nearly twice as large as the prominent crater Copernicus on Earth’s moon. But did this impact really cause the extinction of the dinosaurs and many other forms of life? Many earth scientists are convinced that it did, but some harbor nagging doubts. The doubters have marshaled a growing body of evidence for another culprit; the enormous volcanic eruptions that produced the Deccan Traps formation in India. The skeptics recently presented their case at a meeting of the Geological Society of America in Vancouver, Canada, on October 19.

The dinosaurs are the most well-known victims of the mass extinction event that ended the Cretaceous period. The extinction claimed almost all large vertebrates on land, at sea, or in the air, as well as numerous species of insects, plants, and aquatic invertebrates. At least 75% of all species then existing on Earth vanished in a short span in relation to the geological timescale of millions of years. The disaster is one of five global mass extinction events that paleontologists have identified over the tenure of complex life on Earth.

The hypothesis that the terminal Cretaceous extinction was caused by a cosmic impact has been the most popular explanation of this catastrophe among earth scientists and the public for several decades. It was proposed in 1980 by the father and son team of Luis and Walter Alvarez and their collaborators. The Alvarez team’s main line of evidence that an impact happened was an enrichment of the metal iridium in sediments dating roughly to the end of the Cretaceous. Iridium is rare in Earth’s crust, but common in meteorites. The link between iridium and impacts was first established by studies of the samples returned by the Apollo astronauts from the Moon.

Over the ensuing decades, evidence of an impact accumulated. In 1991, a team of scientists led by Dr. Alan Hildebrand of the Department of Planetary Sciences at Arizona University, published evidence of a gigantic buried impact crater, called Chicxulub, in Mexico. Other investigators found evidence of materials ejected by the impact, including glass spherules in Haiti and Mexico. Supporters of the impact hypothesis believe that vast amounts of dust hurtled into the stratosphere would have plunged the surface of the planet into the darkness and bitter cold of an “impact winter” lasting for at least months, and perhaps decades. Global ecosystems would have collapsed and mass extinction ensued. But, they’ve had a harder time finding evidence for these consequences than for the impact itself.

Doubters of the Alvarez hypothesis don’t question the ‘smoking gun’ evidence that an impact happened near the end of the Cretaceous, but they don’t think it was the main cause of the extinctions. For one thing, inferring the exact time of the impact from its putative geological traces has proved difficult. Dr. Gerta Keller of the Department of Geosciences of Princeton University, a prominent skeptic of the Alvarez hypothesis, has questioned estimates that make the impact and the extinctions simultaneous. Analyzing core samples taken from the Chicxulub crater, and glass spherule containing deposits in northeastern Mexico, she concludes that the Chicxulub impact preceded the mass extinction by 120,000 years and had little consequence for the fossil record of life in the geological formations which she studied. Of the five major mass extinction events in Earth’s history, she noted in a 2011 paper, none other than the terminal Cretaceous event has ever been even approximately associated with an impact. Several other large impact craters besides Chicxulub have been well studied by geologists and none is associated with fossil evidence of extinctions. On the other hand, four of the five major mass extinctions appear to have some connection with volcanic eruptions.

Keller and other Alvarez skeptics look to a major volcanic event that occurred towards the end of the Cretaceous as an alternate primary cause of the extinction. The Deccan Traps formation in central India is a plateau consisting of multiple layers of solidified lava 3500 m thick. Today, it extends over an area larger than all of France. It was once three times that large. It was formed in a series of three volcanic outbursts that may have been among the largest in Earth’s history. At the October conference, Dr. Theirry Adatte of the Institute of Earth Sciences at the University of Lausanne in France presented evidence that the second of these outbursts was by far the largest, and occurred over a period of 250,000 years prior to the end of the Cretaceous. During this period, 80% of the total lava thickness of the Deccan formation was deposited. The eruptions produced lava flows that may be the longest on Earth, extending more than 1500 km.

The blue area indicates the Deccan Traps, a massive remnant of immense volcanic eruptions at the end of the Cretaceous period that may have contributed to the terminal Cretaceous extinction. Credit: CamArchGrad, English Wikipedia Project


The blue area indicates the Deccan Traps, a massive remnant of immense volcanic eruptions at the end of the Cretaceous period that may have contributed to the terminal Cretaceous extinction. Credit: CamArchGrad, English Wikipedia Project
To illustrate the likely environmental consequences of such a super-eruption, Adatte invoked the worst volcanic catastrophe in human history. Over eight months from 1783-84 a major eruption in Laki, Iceland, deposited 14.3 square kilometers of lava and emitted an estimated 122 megatons of toxic sulfur dioxide into the atmosphere. About a quarter of the people and half of the livestock in Iceland died. Across Europe the sky was darkened by a pall of haze, and acid rain fell. Europe and America experienced the most severe winter in history and global climate was disrupted for a decade. Millions of people died from the resulting drought and famine. The Laki incident was nonetheless miniscule by comparison with the second Deccan Traps outburst, which produced 1.5 million square kilometers of lava and an estimated 6,500- 17,000 gigatons of sulfur dioxide.

The Deccan Traps eruptions would also have emitted immense quantities of carbon dioxide. Carbon dioxide is a heat trapping greenhouse gas responsible for the oven-like temperatures of the planet Venus. It is released by the burning of fossil fuels and plays a major role in human-caused global warming on Earth. Thus Geller surmised that the Deccan Traps eruptions could have produced both periods of intense cold due to sulfur dioxide haze, and intense heat due to carbon dioxide induced global warming.

At the October conference she presented the results of her studies of geological formations in Tunisia that preserved a high resolution record of climate change during the time of the main pulse of Deccan Traps volcanic activity. Her evidence shows that near the onset of the 250,000 year pulse, there was a ‘hyperthermal’ period of rapid warming that increased ocean temperatures by 3-4 degrees Celsius. She claimed that temperatures remained elevated through the pulse culminating with a second ‘hyperthermal’ warming of the oceans by an additional 4-5 degrees Celsius. This second hyperthermal warming occurred within a 10,000 year period of mega-eruptions, which corresponded with the terminal Cretaceous extinction. The Chicxulub impact occurred during the 250,000 year pulse, but well prior to the extinctions and the hyperthermal event.

The debate over the relative importance of the Chicxulub impact and the Deccan Trap volcanoes in producing the terminal Cretaceous extinction isn’t over. In May of this year, a team headed by Dr. Johan Vellekoop at the Department of Earth Sciences at Ulrecht University in the Netherlands published evidence of a geologically brief episode of cooling which they claim as the first direct evidence of an “impact winter”. Whatever the outcome of the debate, it seems clear that the end of the Cretaceous, with its super-volcanoes and giant impacts, was not a good time for life on Earth.

References and Further Reading:
J. Coffey (2009) The Asteroid that Killed the Dinosaurs, Universe Today.

I. O’Neill (2009) (Were the Dinosaurs Really Wiped Out by an Asteroid? Possibly Not (Update), Universe Today.

G. Keller (2012), The Cretaceous-Tertiary Mass Extinction, Chicxulub Impact, and Deccan Volcanism, Earth and Life, J.A. Talent, Editor, Springer Science and Business media.

E. Klemetti (2013) Local and global impacts of the 1783-84 Laki eruption in Iceland, Wired Science Blogs/Eruptions

J. Vellekoop et al. (2014) Rapid short-term cooling following the Chicxulub impact at the Cretaceous-Paleogene boundary, Proceedings of the National Academy of Sciences USA, 111(2) p. 7537-7541.



About 

Paul Patton is a freelance science writer. He holds a Bachelor's degree in physics from the University of Wisconsin Green Bay, a Master's degree in the history and philosophy of science from Indiana University, and a Doctorate in neuroscience from the University of Chicago. He has been interested in space, astronomy, and extraterrestrial life since early childhood.
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Two Comet Groups Discovered Around Beta Pictoris

Two Comet Groups Discovered Around Beta Pictoris:

This artist’s impression shows exocomets orbiting the star Beta Pictoris. Credit: ESO/L. Cacada


This artist’s impression shows exocomets orbiting the star Beta Pictoris. Credit:
ESO/L. Cacada
Between the years 2003 and 2011, the High Accuracy Radial velocity Planet Searcher – better known as HARPS – made more than a thousand observations of nearby star, Beta Pictoris. On board the ESO 3.6-metre telescope at the La Silla Observatory in Chile, the sensitive instrument normally combs the sky nightly in search of exoplanets, but lately it has contributed to another astounding discovery… exocomets!

Located about 63 light-years from the Sun, Beta Pictoris is a youthful star, estimated to be only around 20 million years old. Keeping it company in space is a vast disc of material. This swarm of gas and dust is the beginnings of an active planetary system and was likely created by the destruction of comets and collisions of rocky bodies like asteroids. Now a French team using HARPS has been able to create the most complete catalog of comets to date from this system. Researchers have found no less than five hundred comets belonging to Beta Pictoris and they divide in two unique branches of exocomets. Split into both old and new, these two active flows behave much like our own cometary groups… They have either made many trips around the parent star or are the product of a recent breakup of one or more objects.

Flavien Kiefer (IAP/CNRS/UPMC), lead author of the new study, sets the scene: “Beta Pictoris is a very exciting target! The detailed observations of its exocomets give us clues to help understand what processes occur in this kind of young planetary system.”

Beta Pictoris is located about 60 light-years away towards the constellation of Pictor (the Painter's Easel) and is one of the best-known examples of a star surrounded by a dusty debris disc. Earlier observations showed a warp of the disc, a secondary inclined disc and comets falling onto the star, all indirect, but tell-tale signs that strongly suggested the presence of a massive planet. Observations done with the NACO instrument on ESO’s Very Large Telescope in 2003, 2008 and 2009, have proven the presence of a planet around Beta Pictoris. It is located at a distance between 8 and 15 times the Earth-Sun separation — or Astronomical Units — which is about the distance Saturn is from the Sun. The planet has a mass of about nine Jupiter masses and the right mass and location to explain the observed warp in the inner parts of the disc. This image, based on data from the Digitized Sky Survey 2, shows a region of approximately 1.7 x 2.3 degrees around Beta Pictoris. Credit: ESO/Sky Survey II


Beta Pictoris is located about 60 light-years away towards the constellation of Pictor (the Painter’s Easel) and is one of the best-known examples of a star surrounded by a dusty debris disc. Earlier observations showed a warp of the disc, a secondary inclined disc, and comets falling onto the star, all indirect, but tell-tale signs that strongly suggested the presence of a massive planet. Observations done with the NACO instrument on ESO’s Very Large Telescope in 2003, 2008, and 2009, have proven the presence of a planet around Beta Pictoris. It is located at a distance between 8 and 15 times the Earth-Sun separation — or Astronomical Units — which is about the distance Saturn is from the Sun. The planet has a mass of about nine Jupiter masses and the right mass and location to explain the observed warp in the inner parts of the disc. This image, based on data from the Digitized Sky Survey 2, shows a region of approximately 1.7 x 2.3 degrees around Beta Pictoris. Credit: ESO/Sky Survey II
Just like discovering planets through the transit method, astronomers believe exocomets can cause a disturbance in the amount of light we can see from a given star. When these icy travelers exhaust themselves, their gas and dust tails could absorb a portion of the star light passing through them. For nearly three decades scientists had been aware of minute changes in the light from Beta Pictoris, but attributing it to comets was next to impossible to prove. Their tiny light was simply overpowered by the light of the star and could not be imaged from Earth.

Enter HARPS…

Using more than a thousand observations taken by this sensitive equipment, astronomers chose a sample of 493 exocomets unrelated to each other, but sharing in the Beta Pictoris system. Of these, some were dutifully followed for hours at several different times. The size and speed of the gas clouds produced were carefully measured. Researchers were even able to document the orbital properties of some of these exocomets – the size and shape of their passage paths in relation to the parent star allowing scientists to infer their distances.

Knowing that comets exist around other stars is very exciting – and knowing that solar systems around other stars work much like our own is downright rewarding. Through this study, we’re able to take a unique look at what might be several hundreds of exocomets connected to a solitary exo-planet system. What the research has revealed is two distinct branches of the comet family tree. One of these is old comets – their orbit dictated by a single, massive planet. The other half of the family fork belongs to comets that might have arisen from the destruction of a larger object.

The older group behaves in a predictable manner. These exocomets have differing orbital patterns, and their gas and dust production is greatly reduced. If they follow the same rules as the ones in our solar system, it’s typical behavior for a comet which has exhausted its volatiles during multiple trips around the parent star and is also being controlled by the system’s massive planet. This is exciting because it confirms the planet’s presence and distance!

“Moreover, the orbits of these comets (eccentricity and orientation) are exactly as predicted for comets trapped in orbital resonance with a massive planet.” says the science team. “The properties of the comets of the first family show that this planet in resonance must be at about 700 million kilometres from the star – close to where the planet Beta Pictoris b was discovered.”

The second group also behaves in a predictable manner. These exocomets have nearly identical orbits and their emissions are active and radical. Observations of this cometary type tell us they more than likely originated from the destruction of a larger body and the rubble is caught in a orbit which allows the fragments to graze Beta Pictoris. According to the research team: “This makes them similar to the comets of the Kreutz family in the Solar System, or the fragments of Comet Shoemaker-Levy 9, which impacted Jupiter in July 1994.”

Flavien Kiefer concludes: “For the first time a statistical study has determined the physics and orbits for a large number of exocomets. This work provides a remarkable look at the mechanisms that were at work in the Solar System just after its formation 4.5 billion years ago.”

Original Story Source: “Two Families of Comets Found Around Nearby Star – Biggest census ever of exocomets around Beta Pictoris” – ESO Science News Release



About 

Tammy is a professional astronomy author, President Emeritus of Warren Rupp Observatory and retired Astronomical League Executive Secretary. She’s received a vast number of astronomy achievement and observing awards, including the Great Lakes Astronomy Achievement Award, RG Wright Service Award and the first woman astronomer to achieve Comet Hunter's Gold Status.
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The Physics Behind “Intellstellar’s” Visual Effects Was So Good, it Lead to a Scientific Discovery

The Physics Behind “Intellstellar’s” Visual Effects Was So Good, it Lead to a Scientific Discovery:

Image Credit: Paramount Pictures


Kip Thorne’s concept for a black hole in Interstellar. Credit: Paramount Pictures
While he was working on the film Interstellar, executive producer Kip Thorne was tasked with creating the black hole that would be central to the plot. As a theoretical physicist, he also wanted to create something that was truly realistic and as close to the real thing as movie-goers would ever see.

On the other hand, Christopher Nolan – the film’s director – wanted to create something that would be a visually-mesmerizing experience. As you can see from the image above, they certainly succeeded as far as the aesthetics were concerned. But even more impressive was how the creation of this fictitious black hole led to an actual scientific discovery.


In short, in order to accurately create a visual for the story’s black hole, Kip Thorne produced an entirely new set of equations which guided the special effects team’s rendering software. The end result was a visual representation that accurately depicts what a wormhole/black hole would look like in space.

Artist's conception of the event horizon of a black hole. Credit: Victor de Schwanberg/Science Photo Library


Artist’s conception of the event horizon of a black hole. Credit: Victor de Schwanberg/Science Photo Library
This was no easy task, since black holes (as the name suggests) suck in all light around them, warp space and time, and are invisible to all but X-ray telescopes (due to the bursts of energy they periodically emit). But after a year of work by 30 people and thousands of computers, Thorne and the movie’s special effects team managed to create something entirely realistic.

Relying entirely on known scientific principles, the black hole appears to spin at nearly the speed of light, dragging bits of the universe along with it. Based on the idea that it was once a star that collapsed into a singularity, the hole forms a glowing ring that orbits around a spheroidal maelstrom of light, which seems to curve over the top and under the bottom simultaneously.

To simulate the accretion disk, the special effects team generated a flat, multicolored ring and positioned it around their spinning black hole. Then something very weird and inspiring happened.

McConaughey explores another world in Interstellar (top). Thorne’s diagram of how a black hole distorts light. Credit: Kip Thorne


Thorne’s diagram of how a black hole distorts light. Credit: Kip Thorne
“We found that warping space around the black hole also warps the accretion disk,” explained Paul Franklin, a senior supervisor of Academy Award-winning effects house Double Negative. “So rather than looking like Saturn’s rings around a black sphere, the light creates this extraordinary halo.”

The Double Negative team thought it must be a bug in the renderer. But Thorne realized that they had correctly modeled a phenomenon inherent in the math he’d supplied.

“This is our observational data,” he said of the movie’s visualizations. “That’s the way nature behaves. Period.” Thorne also stated that he thinks he can get at least two published articles out of it.

But more important than that is the fact that Thorne, a thoroughgoing scientist and lover of the mysteries of space and physics, has a chance to show a mass audience some real, accurate science.

The movie premiers in North America on November 7th.

Christopher Nolan and Kip Thorne explain the science behind creating the movie’s black hole.



Further reading: Wired



About 

Author, freelance writer, educator, Taekwon-Do instructor, and loving hubby, son and Island boy!
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Hubble Composite Picture Shows How Close Siding Spring Comet Was To Mars

Hubble Composite Picture Shows How Close Siding Spring Comet Was To Mars:

Comet Siding Spring near Mars in a composite image by the Hubble Space Telescope, capturing their positions between Oct. 18 8:06 a.m. EDT (12:06 p.m. UTC) and Oct. 19 11:17 p.m. EDT (Oct. 20, 3:17 a.m. UTC). Credit: NASA, ESA, PSI, JHU/APL, STScI/AURA


Comet Siding Spring near Mars in a composite image by the Hubble Space Telescope, capturing their positions between Oct. 18 8:06 a.m. EDT (12:06 p.m. UTC) and Oct. 19 11:17 p.m. EDT (Oct. 20, 3:17 a.m. UTC). Credit: NASA, ESA, PSI, JHU/APL, STScI/AURA
We’ve seen spectacular images of Comet Siding Spring from Mars spacecraft, showing just how close the small body was to the Red Planet when it whizzed by Sunday (Oct. 19). But how close were the two objects actually, in the sky? This Hubble Space Telescope composite image shows just how astoundingly near they were.

Above are two separate exposures taken Oct. 18-19 EDT (Oct. 18-20 UTC) against the same starry field image from another survey. It was a complicated shot to get, NASA explains, but it does serve as a powerful illustration of the celestial close encounter.

“This is a composite image because a single exposure of the stellar background, comet Siding Spring, and Mars would be problematic. Mars is actually 10,000 times brighter than the comet, and so could not be properly exposed to show detail in the Red Planet,” NASA stated.

High resolution image pairs made with HiRISE camera on MRO during Comet Siding Spring's closest approach to Mars on October 19. Shown at top are images of the nucleus region and inner coma. Those at bottom were exposed to show the bigger coma beginning of a tail. Credit: NASA/JPL/Univ. of Arizona

High resolution image pairs made with HiRISE camera on MRO during Comet Siding Spring’s closest approach to Mars on October 19. Shown at top are images of the nucleus region and inner coma. Those at bottom were exposed to show the bigger coma beginning of a tail. Credit: NASA/JPL/Univ. of Arizona
“The comet and Mars were also moving with respect to each other and so could not be imaged simultaneously in one exposure without one of the objects being motion blurred. Hubble had to be programmed to track on the comet and Mars separately in two different observations.”

The two images were blended together in this single shot, showing their separation of 1.5 arc minutes (1/20 of the Moon’s apparent diameter.) The background stars comes from data from the Palomar Digital Sky Survey “reprocessed to approximate Hubble’s resolution”, NASA stated.

While the nucleus is too small to be imaged by Hubble, you can see what it looks like in the image above from the Mars Reconnaissance Orbiter. Siding Spring passed by the Red Planet at a distance of just 87,000 miles (140,000 km).

Source: NASA



About 

Elizabeth Howell is the senior writer at Universe Today. She also works for Space.com, Space Exploration Network, the NASA Lunar Science Institute, NASA Astrobiology Magazine and LiveScience, among others. Career highlights include watching three shuttle launches, and going on a two-week simulated Mars expedition in rural Utah. You can follow her on Twitter @howellspace or contact her at her website.
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Asteroid 2014 SC324 Zips By Earth Friday Afternoon – Tips on How to See it

Asteroid 2014 SC324 Zips By Earth Friday Afternoon – Tips on How to See it:

Here comes another asteroid! 2014 SC324 will miss Earth by 1.5 times the distance to the Moon early Friday afternoon October 24, 2014. Credit: Gianluca Masi / Software Bisque


Here comes another asteroid! 2014 SC324 will miss Earth by 1.5 times the distance to the Moon early Friday afternoon October 24, 2014. Credit: Gianluca Masi / Software Bisque
What a roller coaster week it’s been. If partial eclipses and giant sunspots aren’t your thing, how about a close flyby of an Earth-approaching asteroid?  2014 SC324 was discovered on September 30 this year by the Mt. Lemmon Survey high in the Catalina Mountains north of Tucson, Arizona. Based on brightness, the tumbling rock’s size is estimated at around 197 feet (60-m), on the large side compared to the many small asteroids that whip harmlessly by Earth each year.

Illustration of small asteroids passing near Earth. Credit: ESA / P. Carril


Illustration of small asteroids passing near Earth. Credit: ESA / P. Carril
Closest approach happens around 2 p.m. CDT (7 p.m. UT) Friday afternoon when our fast friend flies misses Earth by just 351,000 miles (565,000 km) or 1.5 times the distance to the Moon. This is a very safe distance, so we can finish up our lunches without a jot of concern. But the asteroid’s  combination of size and proximity means amateur astronomers with a 10-inch or larger telescope will be able to track it across the sky beginning tonight (Oct. 23) and continuing through tomorrow night. 2014 SC324 should shine tolerably bright this evening at around magnitude +13.5.

Bright here is something of a euphemism, but when it comes to new Earth-approaching asteroids, this is within range of many amateur instruments. And because 2014 SC324 is “only” a half million miles away tonight, it’s not moving so fast that you can’t plot its arc on a single star chart, spot it and go for a ride.


Simulation based on recent data showing the known asteroids orbiting the Sun

By Friday evening, the new visitor will have faded a bit to magnitude +14. You can create a track for 2014 SC324 by inputting its orbital elements into a variety of astro software programs like MegaStar, the Sky and Le Ciel. Elements are available via the Minor Planet Center and Horizons. Once saved, the program will make a track of the asteroid’s movement at selected time intervals. Print out the chart and you’re ready for the hunt!

You can also go to Horizons, ask for a list of positions every 15 minutes for example and then hand plot those positions in right ascension (R.A.) and declination (Dec.) on a star map.  This is what I do. I find the the general chunk of sky the asteroid’s passing through, print the map and then mark positions in pencil and connect them all with a line. Now I’ve got a chart I can use at the telescope based on the most current orbit.

Tonight the errant mountain will rumble through Aries the Ram, which is conveniently located in the eastern sky below Andromeda and the Great Square of Pegasus at nightfall.

Finding a dim, fast-moving object is doubtless an exciting challenge, but if you lack the equipment or the weather doesn’t cooperate, you can see the show online courtesy of Italian astrophysicist Gianluca Masi. He’ll stream the close encounter live on his Virtual Telescope Project website beginning at 7 p.m. CDT (midnight UT) tomorrow night October 24-25.

Clear skies!



About 

I'm a long-time amateur astronomer and member of the American Association of Variable Star Observers (AAVSO). My observing passions include everything from auroras to Z Cam stars. Every day the universe offers up something both beautiful and thought-provoking. I also write a daily astronomy blog called Astro Bob.
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All Three NASA Mars Orbiters Healthy After Comet Flyby

All Three NASA Mars Orbiters Healthy After Comet Flyby:

Artist's concept showing NASA's Mars orbiters lining up behind the Red Planet This artist's concept shows NASA's Mars orbiters lining up behind the Red Planet for their "duck and cover" maneuver to shield them from comet dust from the close flyby of comet Siding Spring (C/2013 A1) on Oct. 19, 2014.

› Full image and caption
All three NASA orbiters around Mars confirmed their healthy status Sunday after each took shelter behind Mars during a period of risk from dust released by a passing comet.

Mars Odyssey, Mars Reconnaissance Orbiter and the Mars Atmosphere and Volatile Evolution (MAVEN) orbiter all are part of a campaign to study comet C/2013 A1 Siding Spring and possible effects on the Martian atmosphere from gases and dust released by the comet. The comet sped past Mars today much closer than any other known comet flyby of Mars or Earth.

Additional information about the precautions and observations by each of the three orbiters is at:

› Mars Odyssey mission status report

› Mars Reconnaissance Orbiter mission status report

› MAVEN mission status report

For more information about comet Siding Spring and the investigations of its Mars flyby, visit:

http://mars.jpl.nasa.gov/comets/sidingspring/

Media Contact

Guy Webster

Jet Propulsion Laboratory, Pasadena, California

818-354-6278

guy.webster@jpl.nasa.gov

Dwayne Brown

NASA Headquarters, Washington

202-358-1726

dwayne.c.brown@nasa.gov

Nancy Jones / Bill Steigerwald

Goddard Space Flight Center, Greenbelt, Maryland

301-286-0039 / 301-286-5017

nancy.n.jones@nasa.gov / william.a.steigerwald@nasa.gov
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Sunday, October 19, 2014

Gravity’s Magic: New Seafloor Map Shows Earth’s Uncharted Depths

Gravity’s Magic: New Seafloor Map Shows Earth’s Uncharted Depths:

An October 2014 gravity map of the Earth's oceans using data from the European Space Agency's CryoSat mission and the CNES-NASA Jason-1 satellite. Findings include "continental connections" between South American and Africa, and evidence of seafloor spreading in the Gulf of Mexico that took place 150 million years ago. The red dots are volcanoes. Credit: Scripps Institution of Oceanography


An October 2014 gravity map of the Earth’s oceans using data from the European Space Agency’s CryoSat mission and the CNES-NASA Jason-1 satellite. Findings include “continental connections” between South American and Africa, and evidence of seafloor spreading in the Gulf of Mexico that took place 150 million years ago. The red dots are volcanoes. Credit: Scripps Institution of Oceanography
Volcanoes! Seafloor spreading! Hidden ridges and mountains! These are the wonders being revealed in new maps of Earth’s sea floor. And no, it didn’t require a deep-sea dive to get there. Instead we got this information from a clever use of gravity (combining the data of two satellites making measurements from orbit.)

The data has caught the attention of Google, which plans to use this data for its upcoming ocean maps release. Scientists also say the information will tell us more about the 80% of the ocean floor that is either unexamined or obscured by thick sand.

So here’s where the data came from. The Scripps Institution of Oceanography combined information from two satellites — the European Space Agency’s ongoing CryoSat mission and the now defunct Jason-1 satellite from NASA and the French space agency CNES, which was decommissioned in 2013 after nearly 12 years of operations.

CryoSat is designed to map the thickness of ice using a radar altimeter (which is a clue to the effects of climate change). But this altimeter can be used all over the world, including to look at how high the sea floor is. Jason-1, for its part, was told to look at the Earth’s gravity field in the last year of its mission. And what a world pops out when this data is used.

A 2014 view of the Earth's sea floor using data from the European Space Agency's CryoSat mission and the CNES-NASA Jason-1 satellite. Credit: Scripps Institution of Oceanography


A 2014 view of the Earth’s sea floor using data from the European Space Agency’s CryoSat mission and the CNES-NASA Jason-1 satellite. Credit: Scripps Institution of Oceanography
“The effect of the slight increase in gravity caused by the mass of rock in an undersea mountain is to attract a mound of water several meters high over the seamount. Deep ocean trenches have the reverse effect,” ESA wrote in a statement.  “These features can only be detected by using radar altimetry from space.”

Some of the new findings include finding new bridges between Africa and South America and uncovering seafloor spreading that happened in the Gulf of Mexico 150 million years ago. Results based on the study, led by Scripps’ David Sandwell, recently appeared in the journal Science.

Long-time readers of Universe Today may also recall a gravity map from ESA’s Gravity Field and Steady-State Ocean Circulation Explorer (GOCE), which revealed Earth’s gravity as a lumpy potato shape in 2011.

Source: European Space Agency

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Comet A1 Siding Spring vs Mars: Views in Space and Time

Comet A1 Siding Spring vs Mars: Views in Space and Time:

NEOWise


Incoming: NEOWise spies Comet A1 Siding Spring in early August of 2014. Credit: NASA.
Oh, to be a stranded astronaut on the surface of the planet Mars this week.  There’s a great scene from Andy Weir’s recent novel The Martian where chief protagonist Mark Watney uses the swift moving moons of Phobos and Deimos to roughly gauge his direction while travelling across the expansive Martian desert.

This week, the skies over Mars will also be graced by an unforgettable and spectacular sight: the extremely close passage of Comet C/2013 A1 Siding Spring. The first comet discovered in 2013, A1 Siding Spring was spotted by veteran comet hunter Robert McNaught from the Siding Spring Observatory in Australia. Dozens of comets are discovered in any given year, but this one soon gained the attention of astronomers when it was found that the comet could possibly hit Mars in October 2014.

And although further observations refined A1 Siding Spring’s orbit and ruled out such an impact, the particulars of the close passage of the comet past Mars are still stunning: A1 Siding Spring will pass within 87,000 miles (139,500 kilometres) from the center of Mars on Sunday, October 19th at 18:27 Universal Time (UT) or 2:27 PM EDT.

And although we’ve yet to set “boots” on Mars, a fleet of spacecraft arrayed throughout the inner solar system are set to study the comet from both near and far. NASA has taken measures to assure that spacecraft in orbit are afforded maximum protection from incoming cometary debris, and the exciting possibility exists that we’ll be able to study first-hand the interaction of the comet’s tail with the Martian atmosphere.

Credit NASA


Mars-based spacecraft set to observe Comet A1 Siding Spring: a scorecard. Credit: NASA.
Universe Today has written extensively on the scientific efforts to study the event, how to observe the comet from Earth, and the unprecedented amateur and professional campaign in progress to witness the close pass.

What we’d like to do now is imagine the unparalleled view under alien skies as the comet slides gracefully overhead.

The nucleus of A1 Siding Spring is thought to be 700 metres across, and the coma extends 19,300 km in diameter. The comet’s closest passage is just under six times the distance of Mars’ outer moon Deimos, and at closest approach, the coma will appear almost 8 degrees in size to any would-be Martian — that’s 16 times the diameter of a Full Moon as seen from the Earth — and will be crossing the skies at a staggering 1.5 degrees a minute. You would be able to easily see the motion of the comet as it moves across the Martian sky with the unaided (well, space suit helmet protected) eye after just a few dozen seconds worth of watching! The comet’s magnitude may reach -5 as seen from Mars, though that would also be extended over its huge expanded surface area.

The enormous tail of the comet would also span the sky, and NASA has already released several mind blowing simulations to this effect.  We’ve also constructed some brief simulations using Starry Night that show the view of the encounter from Earth, Phobos, and the perspective from the comet itself:



There’s also been some discussion as of late that A1 Siding Spring has slowed down in terms of its predicted brightening, though this is not unusual or unexpected.

From Acidalia Planitia (the setting for The Martian) located in the mid-northern latitudes on the surface of Mars, the comet would be a fine morning object, sitting 48 degrees above the northeastern horizon at dawn at closest passage for one morning only, and perhaps staying visible even after sunrise. Earth would be in the picture too, shining at magnitude -2.5 in the Martian dawn.

Mars


Dawn on  October 19th, 2014, as seen from Mars. Created using Starry Night.
And the view from the comet?  Now that would be a truly spectacular ride, as Mars swells to 3 degrees in diameter as it approaches and recedes. The comet itself is on a million year plus orbit, never to again visit the realm of the inner solar system in our lifetimes.

Such a view has never been seen in recorded history from the Earth. The closest confirmed passage of a large comet near our planet was Comet D/1770 L1 Lexell, which passed over 15 times more distant than A1 Siding Spring from Mars, at 2.2 million km from Earth on July 1st, 1770. Note that an even closer cometary passage in 1491 remains unverified. In more recent times, Comet Hyakutake passed 15.8 million km from Earth on March 25th, 1996, with a tail that spanned half the sky as seen from a dark sky site, and long-time comet observers might also remember the 1983 passage of Comet IRAS-Araki-Alcock, which passed just 4.7 million kilometres from the Earth.

Credit:


A1 Siding Spring imaged from Earth on October 11th, 2014. Credit: Efrain Morales Rivera.
And then there was the historic impact on Comet Shoemaker-Levy 9 into Jupiter in 1994, reminding us that cosmic catastrophes can and do indeed occur… the upper size limit estimate for the nucleus of A1 Siding Spring compares to 70% the size of Fragment G, and an impact on Earth or Mars of such a dirty snowball would be a very bad day, for rovers or the humans. An extinction level event such as the Chicxulub impactor, however, was estimated to be much larger, at about 10 km in size.

Credit:


A1 Siding Springs as imaged on September 3rd, 2014. Credit: Roger Hutchinson.
Thankfully, we’ve merely got a front row seat to the show this weekend, and our planet is not the main event. From Earth, Comet A1 Siding Spring will be a binocular object, shining at magnitude +9 as it passes 3’ from +0.9 magnitude Mars. Both will be visible briefly in dusk skies, and the Virtual Telescope Project also plans to broadcast the event live starting at 16:45 UT on October 19th.

Don’t miss the historic passage of Comet A1 Siding Spring past Mars… by this time next week, we fully expect more images of the comet — both amateur and professional — to grace the cyber-pages of Universe Today!

  • Imaging A1 Siding Spring and/or Mars? Send those astro-pics into Universe Today at our Flickr forum.
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