Changing Planet

Monster Comet may have Mars in its Crosshairs

Mars may have a really bad day next year on October 19th.    That’s when there is a very slight chance a newly discovered comet may impact our neighboring planet, says NASA.

Comet C/2013 A1 (Siding Spring) was discovered by Australian Robert H. McNaught, a prolific comet and asteroid hunter just two months ago and NASA’s Near-Earth Object Program Office at the Jet Propulsion Laboratory , in Pasadena, Calif., has been constantly refining the comet’s exact trajectory ever since.

Latest orbital calculations have the icy visitor passing by Mars  at only 31,000 miles (50,000 kilometers) – only two-and-a-half times the distance that the outer moon Deimos orbits.

A giant comet is heading for a close encounter with the planet Mars in October 2014. Image courtesy of NASA/JPL
A giant comet is heading for a close encounter with the planet Mars in October 2014. Image courtesy of NASA/JPL


Astronomers watching the icy interloper predict that as more observations are accumulated over time,  it’s more and more likely Mars is going to dodge the bullet and only get a close shave . The possibility of impact however has not been completely ruled out yet, says NASA, giving the comet a 1 in 600 chance of walloping the Red Planet.

If Siding Spring would hit, the force of impact may truly be monumental. Based on observations to date the comet nucleus could be a real monster – as big as 9 miles (15 km) to 31 miles (50 km) wide. With it’s velocity clocked at 35 miles (56 km) per second, the energy force of the collision could be measured in the billions of megatons, resulting in a crater hundreds of miles wide.  This could be an impact that rivals the one that wiped out the dinosaurs 65 million years ago on our planet and would be bright enough to be even seen with the naked eye from Earth. (See “Russian Meteorite Spotlights History’s Other Crashes.”)

Chances are however that it will just barely miss the planet, but comet Siding Spring may still become visible through binoculars and backyard scopes for us Earthlings in the Southern Hemisphere around mid-September 2014.  It  should also produce quite a sky show as seen from the surface of Mars.  (See: New Comet Discovered—May Become “One of Brightest in History”)

Current brightness magnitudes estimate that  the comet will be very bright to even the digital eyes of the two working Mars rovers – Opportunity and Curiosity. Can hardly wait to see the amazing photos from these intrepid robotic explorers!

So it will definitely be worth watching what the comet does in the coming weeks and months- whether it impacts Mars or not.

Andrew Fazekas, aka The Night Sky Guy, is a science writer, broadcaster, and lecturer who loves to share his passion for the wonders of the universe through all media. He is a regular contributor to National Geographic News and is the national cosmic correspondent for Canada’s Weather Network TV channel, space columnist for CBC Radio network, and a consultant for the Canadian Space Agency. As a member of the Royal Astronomical Society of Canada, Andrew has been observing the heavens from Montreal for over a quarter century and has never met a clear night sky he didn’t like.
  • jasper johns

    All this recent asteroid business reminds me of this novel I just read called THE MYOSHI EFFECT which is about an asteroid headed toward earth and how everybody reacts and the government tries to find a way to deflect it. Granted the novel is humorous, like Dr Strangelove or Douglas Adams or something, but how we just reacted to these last 2 space rocks is almost taken from the pages of the book. Fiction and fact are fast becoming one.

  • Kevin

    If the comet is made of ICE this could create oceans on mars and the impact could restart the core moving.

  • pos

    I want to see this comet hit one of the Mars moons.
    Phobos measuring 13.4×9.2 km (8.3×5.7 miles) and Deimos at 7.5×5.2 km (4.7×3.2 miles). Mars should not have more moons than us.

  • clark

    With an impact that large what will it do to the rovers if it does hit the planet.

  • Michael

    If the comet hit, wouldn’t it create a greenhouse affect that would warm the planet? If that were the case, then the ice it carries would add oxygen to mars’ atmosphere would it not? Some interesting possibilities.

  • john scarponi

    This is the test we have been waiting for. It is the perfect chance to try to deflect an asteroid/comet from striking a planet. Sure, maybe we don’t care if it hits Mars, but if we could learn how to deflect it, maybe it will save us in the future. Also, could a strike affect Mars’ orbit, thus the Earth’s orbit? Probably can’t get a rocket there that fast, but it’d still be cool to try!

  • Dennis Reiley

    If it comes that close there should be a considerable course deviation unlike that shown in the diagram.

  • C/2013 A1

    I’m just out cruise’n by folks, nothing to see here…

  • Babu G. Ranganathan

    DOES GOD PARTICLE EXPLAIN UNIVERSE’S ORIGIN? Just google the title to access this popular Internet article of mine.

    Babu G. Ranganathan*
    (B.A. Bible/Biology)


    *I have given successful lectures (with question and answer period afterwards) defending creation before evolutionist science faculty and students at various colleges and universities. I’ve been privileged to be recognized in the 24th edition of Marquis “Who’s Who in The East” for my writings on religion and science.

  • wowlfie

    This is bad reporting. Rival the dino killer?

    If it hits Mars it will have 1800 times the energy and DWARF the dino killer into insignificance. That’s really bad reporting.

    The math for this comes straight from Wikipedia and it’s not wrong.

    Dino Killer–6.2 miles, 44,640 mph (est. 12.4 miles/second); total energy 100 teratons of TNT (4.2×1023 J); source Wikipedia.

    Shoemaker 9–9.3 miles, 134,000 mph (estimated); total energy 6,000 teratons of TNT (600 times the world’s nuclear arsenal) or 600 times more powerful than the dino killer. source: Wikipedia.

    Siding Spring -30 miles, 126,000 mph (fairly accurate); total energy estimated 29.7 times larger than the Shoemaker 9 Comet (assuming equal density, .884 velocity squared difference, mass difference of 33.5 difference); 178,200 teratons of TNT. or 178 petatons of TNT.

  • Shoreline Star

    Well as far as creating a greenhouse effect I will venture to say it would probably be more like a temporary pooling of water scattered across a certain amount of area. You must remember that mars has virtually no atmosphere to begin with and the comet if it hits would have nothing to really heat it up before impact. It would basically be a direct cold hit with only the friction of impact creating any vapors.Although the hit would be on a massive scale and there would definately be frictional heating it would not be the same as an object getting super glowing heated through an atmosphere and then deliver an impact. Also the comet is about 30 mi. which in relation to the size of mars is really not near enough water to make any significant changes that would last long enough to support the environments needed to sustain life for any period of time.As far as oxygen into the air Thats a Yes on that one . But again the amounts are relatively miniscule in relation to planet size.Restarting the core is an absolute NO on this one. To restart the core Mars would have to break apart and crumble and then coelesce and come together again spinning and heating into a glowing ball of materiel then the outer layers would have to cool and form a crust to then form a molten core once again and then many thousands of comets over millions of years would have to impact to form oceans and an atmosphere.then just maybe you would get some life forms to begin to take shape.Mars is too far away for the possible impact to effect our orbit however a really large impact like this would would be absolutely fascinating to see. Im afraid that our mars rovers will not fare well as they would be buried under alot of fallout debris no matter where they are located.I will be bold to say I guarantee they would be buried without question.But the data and pics they would send just prior to that would and should be amazing to say the least.Thank You Everyone ! please excuse me for now im going to the kitchen for a big bowl of Captain Crunch and watch cartoons. Sincerely,Shoreline Star

  • LisF

    If Siding Spring slam into Mars, any manned mission to the red planet will be post pone for a very long time.

  • emily

    If it really does hit mars won`t the piece that breaks off go somewhere else

  • GregtheThird

    If the comet impacted, the rovers would be toast due to re-entry of flaming ejecta all over the planet. Opportunity would also lose access to sunlight which it needs to recharge. Global warming would be assured but not for a sustained period of time. There would be regional flooding from the widespread melting of permafrost from the heat generated by the impact. One comet will not release a significant amount of green-house gasses into the atmosphere to create enough global warming to make a long-term difference. Hundreds of comets would, but not one.

  • Albert Rogers

    There are two or three influences that seem not to have been mentioned. One is like the thermal neutron effect. The slower a neutron travels, the more likely it is that the “strong force” between it and a big nucleus will capture it. So the larger the planet, and the slower the missile travels towards it (planetary coordinates) the more likely it will be captured. The energy of impact includes the energy of the fall into that gravity.
    So the largest contributor to the speed at which Shoemaker-Levi hit Jupiter, was probably the gravtational energy of that fall. Earth can capture faster or more distant rocks than Mars can.
    The other thing is, that if the comet is mostly frozen water and methane, the energy of the impact will certainly vaporise, and probably ionise, those compounds. Very little of that wildly energetic hydrogen is likely to remain, in my humble estimation.

  • Albert Rogers

    I had another look at the diagram, and the reported speed. Relative to the planet, that speed is so high I think it would take a direct hit, virtually no gravitational diversion and capture is likely.

  • Ron

    If the impact calculations are correct, according to wowlfie, this comet, at 30 miles across, has the potential of being a planet-killer instead of being just an E.L.E. type comet. Then we on Earth have to be fearful of the particle fallout from the destruction of Mars. Back in 1993, a lot of scientists scoffed at the idea of any sizeable impact Comet Shoemaker-Levy 9 could do to Jupiter. When it hit, it outdid what anyone predicted. The largest of those fragments were only 1.2 miles! If Comet Siding Spring does hit Mars, we should be very afraid of the fallout of Mars’ destruction. Here’s hoping for all of us that it does pass Mars by a whisker! The photos from Opportunity and Curiosity, in either case, would be spectacular, from a scientific perspective.

  • Henry

    There are many stories of comets, near-miss asteroids, and fireballs in the news lately. Comet ISON may dazzle the world on Christmas Day 2013 with its rare brilliance. Comet Siding Spring may indeed spectacularly impact Mars in 2014. Could Michael Rampino’s “Shiva Hypothesis” be correct? Is Earth facing a cosmic hailstorm? Could National Geographic present Rampino’s theory to the general public with a feature article in its magazine? It might sell big-time around Christmas!

  • I Like Food

    Hey, Mars might just lucky, and the comet might destroy Phobos. Wouldn’t that be hell of a reprieve for mars.

  • baba

    we could blow the comet with liquid nitrogen

  • baba

    try using the NUKE at north america

  • baba

    with fireworks and lets bring an astronaut to

    space maybe we should bring cameras if there is something
    terrible happened who knows we can meet aliens at the moon

  • admin 776

    examine the crater

  • Nicole

    I like mars

  • Jasper

    Mars is cool nicole

  • Jasper

    I liked goats on mars.
    From jasper

  • Tail

    If it make impact, it would be really more interesting that if we deviate its course (IMO). Also, if it hit on of the Mars moons, it would create a really spectacular martian ring. Of different colors because the different compositions of the martian moons and the icy comet.

  • Ben Altman

    The impact will not destroy mars nor will it affect us here on earth other than providing us with a rather spectacular light show. Consult the online asteroid impact damage calculator from Purdue and the university of London to see what it would do in terms of ejecta distribution, crater and initial fireball diameters, and quake data, then adjust for mars conditions. It will not affect our orbit nor should it significantly disturb mars orbit, other than perhaps lengthening or shortening the martian day by a few milliseconds. just like Shoemaker-levy made a tiny blip in Jupiter’s enormous mass, siding spring, if it hits (1/2000 chance according to nasas website) will cause plenty of ejecta in mars scant atmosphere for a time and may or may not directly affect the rovers depending on where tgey are when it hits. opportunity will likely go offline, at least til the dust settles. No sweat.

  • Bjorn R.

    I am really scared about this impact of a comet hitting to Mars next year!

  • Kevin Curran

    JPL decreased the odds from 1 in 600 to 1 in 120,000 within a couple months of new observations in early 2013. Looks like Levy-Shoemaker remains the sole comet observed in known human history hitting a planet.

    For more on Comet Siding Spring, including images, video, orbital path, etc, visit

  • Rick Carter

    I am of the opinion that the enormous down range debris field which would be created by a direct hit to Mars (or even one of the moons of Mars) could easily represent an E.L.E. threat to the Earth within a matter of months. But clearly I am almost alone in that concern. – RC

  • Andrew Myers

    Good I want that comet hit mars because it is going to save our billions if not trillions of dollars because that is the cost to terraform mars. And it will be quicker too!

  • Jamie

    How about the Americans use the haarp against the comet if it becomes a threat to earth rather using it to destroy this beautiful planet we call hm

  • cyndi

    I understand Phobos is a rubble pile. Let’s say siding spring doesn’t hit Mars but Phobos, instead. Isn’t this likely to create a debris field Earth will encounter next spring? I for one do not look forward to Earth slamming into the Monolith on Phobos

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