Comet ATLAS continues to brighten, now with an impressive tail, and it could put on quite a dazzling show next month

Guest post by Paul Dorian,


“According to my observations, the tail of Comet ATLAS is 1.2 degrees long,” reports Gerald Rhemann who recorded this image on Friday, March 27th from his backyard observatory in Eichgraben, Lower Austria (courtesy


About a month ago, Comet ATLAS was very difficult to find, but it is now as bright as an 8th magnitude star and has generated quite an impressive tail. This brightness is hundreds of times brighter than astronomers predicted when it discovered the comet several months ago. While it is still too dim to see with the unaided eye, it is becoming an increasingly easy target for backyard telescopes. The comet is expected to become much brighter by the time it sweeps by the sun closer than Mercury during late May, it could even rival Venus in the evening sky.


The orbit of Comet ATLAS and position as of Thursday, April 2nd; courtesy NASA,


Comet ATLAS was discovered by the Asteroid Terrestrial-impact Last Alert System (ATLAS) and has been given the nickname of ATLAS, but its official name is C/2019 Y4.  ATLAS is an asteroid impact early warning system being developed by the University of Hawaii and is funded by NASA. It consists of two telescopes, 100 miles apart, which automatically scan the whole sky several times every night looking for moving objects.  ATLAS will provide one day’s warning for a 30-kiloton “town killer,” a week for a 5-megaton “city killer,” and three weeks for a 100-megaton “county killer”. So far, ATLAS has discovered 427 near-earth asteroids and as many as 37 comets included the one now being referred to as Comet ATLAS.


Location of the ATLAS telescopes; courtesy The ATLAS project, NASA

The comet’s last Earth fly-by was sometime around 4000 BC when it was witnessed by early ancient Egyptian farmers as well as Neolithic tribes in Ireland, northern Scotland and across Scandinavia, but this most recent pass was first spotted on December 28, 2019 by ATLAS. The comet is hundreds of times brighter than originally predicted at the time of discovery and there is increasing hope that it will become quite bright when it approaches the sun during the latter part of the month of May.  Brightness estimates for Comet ATLAS range from magnitude +1 to -10 which is somewhere between a 1st magnitude star and the waxing crescent moon.

The image (top) of Comet ATLAS was taken from a backyard observatory (12-inch telescope) in Austria on Friday, March 27th and shows quite an impressive tail.  In fact, an estimate of the tails length of 1.2 degrees is roughly equivalent to 3.3 million kilometers or more than twice as wide as the sun.  Comet tails are dust and gas that get illuminated by the sun as the comet gets closer. By late May, Comet ATLAS will be only about 0.25 AU away from the sun and getting closer than Mercury (one AU (astronomical unit) is equivalent to the distance between the Earth and the Sun).  Comet ATLAS is known as a hyperbolic comet and is currently in the constellation Ursa Major (the Big Dipper) in the northern sky orbiting Mars.

Stay tuned…predictions of comet brightness have certainly had mixed results in recent history, but there is increasing hope that this one can put on quite a dazzling show later next month. By the end of April, Comet ATLAS will be in the constellation of Camelopardalis and best seen just after sunset, in the western twilight sky. After May, ATLAS will continue its journey towards the center of our solar system, getting closer to the Sun which will make it harder to see. It is expected to come back around in June when it may be visible again on its way out of sight once more.

Meteorologist Paul Dorian
Perspecta, Inc.

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76 thoughts on “Comet ATLAS continues to brighten, now with an impressive tail, and it could put on quite a dazzling show next month

  1. “predictions of comet brightness have certainly had mixed results in recent history, but there is increasing hope that this one can put on quite a dazzling show later next month.”
    So if they are wrong and it passes even closer to earth than currently predicted,what will be the official line;
    “We wanted it bright,but not this bright”?

        • Portends. The coming man-made economic crisis will be far worse than the virus, which has does not even show up on seasonally averaged mortality data.

          Comet ATLAS is known as a hyperbolic comet and is currently in the constellation Ursa Major (the Big Dipper) in the northern sky orbiting Mars.

          Well I seriously doubt that it is “orbiting” anything but the sun.
          Can someone explain what a “hyperbolic orbit” is supposed to be? A hyperbola is conic section which is NOT closed, so you can have a hyperbolic trajectory but not a “hyperbolic orbit” . The fact this it allegedly passed by in 4000BC is again not consistent with a hyperbolic trajectory. Has someone redefined what a hyperbola is ??

          • Greg, that sentence had me scratching my head too.

            A hyperbolic comet with a 6000 year period… I thought hyperbolic implies a one-shot pass of an object that has never been seen before and will never be seen again.

            I can’t make sense of either the Big Dipper or a comet currently orbiting Mars.
            That would give a brand new meaning to ‘New Moon’.

            Knowing to look for the comet in the vicinity of the Big Dipper is helpful. Assuming any of the rest of that sentence is intended to inform I wonder what it means.

          • I think what they mean by “hyperbolic comet” is a “breathtaking, fantastic, stupendous, colossal, once-in-a-million generations, etc, comet.”

            Actually, I don’t know why c/2019 Y4 (ATLAS) was called “hyperbolic,” since its eccentricity is 0.99923. Nearly parabolic, and with perturbation could be driven to hyperbolic some time in the future – but not on this pass. Its incoming period on this pass is about 4,800 years, and its outbound period will be about 5,200 years.

        • Or worse – second term for Trump! Nah… no country could have that many idiots…

          In other news: Gun shops in LA have reopened after being deemed “an essential service”. You couldn’t make it up.

          US gun deaths 2019: 39,773
          US Covid-19 deaths (so far): 6,072

          Look! A squirrel!

          • ” Or worse – second term for Trump! Nah… no country could have that many idiots… ”
            Obama advisor David Plouffe disagrees …..

          • What, are you looking in a mirror?

            I really love the way Trump drives the socialists bonkers (not that they weren’t already bonkers).

            His refusal to kowtow to their inanity causes them to drool on themselves even more than they normally due.

          • The following data is taken from the CDC’s 2017 report :
            1. Heart disease

            Number of deaths per year: 635,260

            Percent of total deaths: 23.1 percent

            2. Cancer

            Number of deaths per year: 598,038

            Percent of total deaths: 21.7 percent

            3. Accidents (unintentional injuries)

            Number of deaths per year: 161,374

            Percent of total deaths: 5.9 percent

            4. Chronic lower respiratory diseases

            Number of deaths per year: 154,596

            Percent of total deaths: 5.6 percent

            5. Stroke

            Number of deaths per year: 142,142

            Percent of total deaths: 5.18 percent

            6. Alzheimer’s disease

            Number of deaths per year: 116,103

            Percent of total deaths: 4.23 percent

            7. Diabetes

            Number of deaths per year: 80,058

            Percent of total deaths: 2.9 percent

            8. Influenza and pneumonia

            Number of deaths per year: 51,537

            Percent of total deaths: 1.88 percent

            9. Kidney disease

            Number of deaths per year: 50,046

            10. Suicide

            Number of deaths per year: 44,965
            (24,000 by self inflicted gun shot.)

            Percent of total deaths: 1.64 percent

            11. Septicemia

            Number of deaths per year: 38,940

            Percent of total deaths: 1.42 percent

            12. Chronic liver disease and cirrhosis

            Number of deaths per year: 38,170

            Percent of total deaths: 1.39 percent

          • Why are you unhappy that guns die? US gun deaths are from melting them down when people turn them in, aren’t they?

          • Not to belabor the subject, but just a reminder, depending on which research you take the time to actually read and comprehend, approximately 262,000,000 innocent unarmed civilians were murdered by governments in the 20th century. Thus even more important to realize the God given inalienable right to bear arms is more a defense against a tyrannical government. So casting aspersions directed at gun ownership makes who the idiot?

        • Biden in the White House would easily be eclipsed by this comet, even on a cloudy night!

          • By next January, the memory care facility nursing staff will be telling Joe he is the President and they need him to take his daily pills if he wants another jello, before he meets with the other G7 leaders to play their afternoon bingo.

    • Imagine if the Comet Impact Emergency Response Team (CIERT) enact the response simulation as well as the World Pandemic Response Team (WPRT) have done. There will not be a steel saucepan in a store let alone a hard hat. The least mental place will be a cruise ship in the middle of an ocean or Nepal this time as the coastal areas are evacuated to escape the modeled Tsunami.

      Latest Washington State results. Looks like COVID-19 has persisted at the same rate of detection for the month of March.

      Date %Positive
      02/03/20 3.2
      03/03/20 33.3
      04/03/20 3.3
      05/03/20 0.0
      06/03/20 7.8
      07/03/20 5.9
      08/03/20 14.1
      09/03/20 9.4
      10/03/20 6.0
      11/03/20 7.5
      12/03/20 6.5
      13/03/20 6.5
      14/03/20 5.8
      15/03/20 5.4
      16/03/20 8.3
      17/03/20 7.3
      18/03/20 6.0
      19/03/20 6.2
      20/03/20 6.6
      21/03/20 7.3
      22/03/20 9.0
      23/03/20 13.3
      24/03/20 10.0
      25/03/20 9.8
      26/03/20 9.1
      27/03/20 10.2
      28/03/20 13.7
      29/03/20 13.6
      30/03/20 13.5
      31/03/20 14.7
      01/04/20 11.8

      • I don’t understand your point. The % positive has risen from 3.2% to 11.8%

        That is neither constant, nor it is “the same rate of detection “.

        • Sorry Greg, Yes you do not understand my point. Everything is relative including whether a comet passing within tens of millions of miles is a near miss or you could view this data set as starting on the 3rd of March and then not understanding why the rate of detection had fallen from 33.3%.
          Let’s just say that I am pretty sure I will be around to enjoy watching this comet’s tail trail away from the sun like the magnificent and unexpected show of the Comet Hale-Bopp and not sitting in a biosphere with a face mask on worrying about images of increased detection due to increased testing.

          • I don’t see why you chose on outlier %age caused by noise of very small numbers and them manage to ignore the general rise in rest of that data.

            You talk of “rate of detection”, rate implies time variance. What it seems you meant was the proportion of +ve tests was persistent for the month of March, which it was not.

            You have a good point about testing rates inflating cases. In France testing rates (no. of tests per day ) have been increasing exponentially for more than a month , masking the fact that infection rates must have peaked at least a week or two ago.

            I’m trying to work out how to correct for that bias.

        • Unable to reply to your subsequent posts.

          Thanks Greg and I am not being facetious.

          My plot of the proportion of those tested and reported by the University of Washington as positive to the COVID-19 would appear to show little sign of a trend over the Month of March. I say that as I believe there is a large margin of error in the test itself. (The replication method is largely interpretive).
          Thanks for the French link.

    • Also cue the, “There is an alien space Mother ship hiding behind the comet coming to harvest Earth.”

    • Signs in the heavens are largely ignored in these modern times. Otherwise we would be making a big deal of the return of Jupiter and Saturn beside each other in the morning sky, with the God of war (Mars) passing in front of both, during this pandemic.

      • What a year for a HUGE comet. I hope it doesn’t break up or get swallowed by the Sun. Back in 2013 , I was really looking forward to the ISON comet, but it didn’t make it.

  2. ” Comet ATLAS is known as a hyperbolic comet and is currently in the constellation Ursa Major (the Big Dipper) in the northern sky orbiting Mars.” ???

    • @ Steve Reddish

      Comet ATLAS is known as a hyperbolic comet and is currently in the constellation Ursa Major (the Big Dipper) in the northern sky orbiting Mars.

      Me thinks an editor or reporter screwed up,….. and instead of writing “(currently) in the northern sky orbiting Mars”, ….. it should have stated “(currently) in the northern sky approaching the orbit of Mars”,

      Check the included graphic titled ….. “The orbit of Comet ATLAS

      • Or perhaps the comet’s distance from the sun is currently about the same as Mars’.

        My first look at the included graphic interpreted the comet being in a different plane than planetary orbits, and not approaching any planet’s orbit other than Mercury’s. The graphic has the limitation of a 2D representation of a 3D system where different pairs of eyes can perceive it differently.

        • @ Nick Werner
          My first look at the included graphic interpreted the comet being in a different plane than planetary orbits

          I thought the same thing and it looked to me like it is shown to be at 35+- degrees to the ecliptic.

          Which is good because that increases its odds of getting in and back out of our solar system. 😊

    • In medieval Japanese Buddhist lore, the Big Dipper was called “Hagunsei,” or “the stars of martial destruction,” among celestial objects used by samurai strategists’ divination predictions before battle.

  3. “has been given the nickname of ATLAS, but its official name is C/2019 Y4.”
    Actually, ATLAS is not a nickname, but the comet’s “real” name.
    And C/2019 Y4 is not its “official name”, but its official designation.

    • Me neither. Did you understand a hyperbolic “orbit”. A hyperbola is non closed form, it cannot be an “orbit” and can not come every 6ka.

      Either someone redefined “orbit” or redefined hyperbolic.

      • Well GEEEEEZZE, …… look at the included graphic again and you can plainly see that “hyperbolic orbit”.

        the pictured “orbit” is not connected at the top left ….. because the graphic is not big enough to show

      • An orbit is the path described by an object, so it can be hyperbolic. Where is the problem?
        Some authors use the word “orbit” while they mean “revolution”. In the course of one year, the planet Mercury performs 4 revolutions (not 4 orbits) around the Sun.

  4. Of course comets were considered messengers of death or conflagration in ancient times. Guess this one was a little late but I doubt they would have paid attention to that little detail back then. IMO they are beautiful things to see despite the potential threat huge hunks of dirty ice represent when they come tearing into the inner solar system.

  5. “… orbiting Mars.” Are you sure about this? OTOH, could be worse. Could be orbiting Uranus.

  6. The statements of being a ‘hyperbolic’ comet and of having been seen 4000 years ago are mutually exclusive. If the orbit is hyperbolic it is a sporadic comet, never seen before. That might explain the unexpectedly increased brightness as it likely never has been close to a star. If it’s a returning comet its orbit is a very elogated ellipse and the comet has likely made several appearances before. Then it’s unexpected brightness could be a sign that it is on the point of breaking up and that it won’t survive this passage. Time will tell.

    • Agreed, I don’t understand that either. Hyperbolic orbit is an oxymoron, it would be a hyperbolic trajectory.

    • Oumuamua and Borisov seem to the only known examples of “hyperbolic orbits” before this. The term seems to be used, so someone in astronomy has redefined what these words mean.

      • More likely, someone in the PR department who took the astronomy equivalent of “Physics for Poets” in journalism school. And failed.

  7. Oh No! Plagues, Comets, Locusts, Climate Change… It’s the end of the world! /sarc/

  8. My favorite comet was Hail Bob!

    The comet’s last Earth fly-by was sometime around 4000 BC when it was witnessed by early ancient Egyptian farmers as well as Neolithic tribes in Ireland, northern Scotland and across Scandinavia, …

    The Chinese, who had writing then, didn’t think it was worth noting.

      • It’s listed among the ‘near parabolic’ comets.

        The following is a list of comets with a very high eccentricity (generally 0.99 or higher) and a period of over 1,000 years that don’t quite have a high enough velocity to escape the Solar System. Often, these comets, due to their extreme semimajor axes and eccentricity, will have small orbital interactions with planets and minor planets, most often ending up with the comets fluctuating significantly in their orbital path. link

        The comet has its own wiki page. link Various calculations put its orbital period between 4400 and 6000 years.

        • Hyperbolic is binary choice, it either is or it is not , it either returns or does not.

          I guess astromony is going the same way as climatology where you can scream about “ice free summers ” and walk it back to “nearly ice free, except for 1 million square km” once you get challenged.

          The age of enlightenment is coming to a rapid end.

          • Right: if it is returning, the orbit is elliptical, by definition. A hyperbolic comet is a one-time event.

        • Thanks Bob, ‘near parabolic’ , right. Parabolic is the dividing line between elliptic and hyperbolic, so I guess that means nearly near hyperbolic.

          So the allegedly recurring hyperbolic “orbit” is a load of hyperbollix.

    • “The Chinese, who had writing then”

      No. Nobody had writing 4000 BC. The first pictographic scripts (Sumerian and Proto-Elamite) are from c. 3500 BC. The oldest known Chinese writing is fom the Shang Dynasty, about 1350 BC, but it was already fairly elaborate then, so it might actually have been invented during the Hsia Dynasty three or four centuries earlier.

      • It depends on a lot of things. Our alphabet is phonetic. Chinese is not. Many modern symbols are based on ancient pictographs with the same meaning. That makes it difficult to nail down when the Chinese had a fully developed writing system. link

  9. Greg,
    you are rightly ‘hung up’ on the hyperbolic thing which I agree seems an oxymoron. We should heed my early ancestors (the Neolithic Irish) fear of fairies pookas and asteroids or even haemorrhoids – I am not too sure of the difference!
    I do, however, take issue with the term ‘near miss’

    Think about it for a second -it should be a near hit.
    I could never understand the former term, a near miss means we have been ‘slightly hit’
    Ok I am being pedantic.

    • Hung up, no, but I do think that using the right term matters in science. We are not writing poetry here, it is supposed to be a scientific description of the orbit. That is clearly defined mathematically. Astronomy is supposed to be an exact science, not an oxymoronic poetry convention.

      A near miss is a miss which came near. I would rather take issue with all these “near misses” which are nowhere near at all. If it comes within the lunar orbit it may be worth looking twice.

  10. This has Lucifer’s hammer qualities written all over it. if you have not read the book, you should. People are saying it is not a danger to the earth, although it will pass very close to earth. Is anyone taking into account that leaking gasses from the comet, as it gets closer to the sun, could push the orbit/trajectory closer to earth or further away for that matter? This is a near miss as far as I’m concerned. Any insight from people who know a lot more than me would be appreciated.

    Really, if this was going to hit, what would be the perfect distraction from a life ending event like a Comet hitting us? Well a pandemic would be the perfect distraction. While we are all focused on the pandemic no one is thinking about a comet. I’m playing devils advocate here, not trying to stir up a conspiracy theory.

    • Beng,

      Hale Bopp was better, 1995. Where were you observing from? Though Hyakutake was also very good. Though I do have pics of both, and others, they were the best in my opinion. And that was with old fashioned real film!


      • JimG1 Comet Hale-Bopp was discovered in 1995 but reached perihelion and closest to the earth in March 1997. H-B was an intrinsically monster of a comet. In 1996 a much smaller comet, Hyakutake, was discovered. Hyakutake became the Great Comet of 1996 and is rated in the top five of Great Comets by modern observers. The following year H-B put on its lengthy display mostly in Feb & March of ’97. H-B never approached the size, in this case we refer to comet tail length, seen the year before with Hyakutake, but H-B made up for that with brightness. This was mainly in the form of the very strong dust tail that could be seen from even downtown city locations! H-B became the Great Comet of 1997 & went on to take the record for being visible to the naked-eye for the longest period! The difference between the two comets was geocentric distance. From memory the much smaller Hyakutake came as close as 10 million miles to earth. H-B always remained on the far side of the sun in relation to the earth. Had H-B come as close to us as Hyakutake, H-B would probably have been visible in daylight for weeks, and we would have seen not only those 29 souls who tried to hitch a ride, but hundreds if not thousands of like minded creatures susceptible to those sort of influences. It is all in the timing. If the earth is at the right place at the right time we could all be dazzled by a fleeting spectacle in the night sky just as our ancestors were, but with the knowledge we have now to appreciate comets for what they really are. At perihelion (May 31st) ATLAS will emerge into our southern hemisphere dawn sky with its tail pointing up and directly away from the sun. We will know by then, thanks to northern hemisphere observers, whether or not this comet will be of the Great variety, or just a fine comet best seen in bino’s!

      • Hale-Bopp was one we knew was coming and looked forward to it eagerly.

        All of a sudden, Hyakutake showed up virtually unannounced and stole some of Hale-Bopp’s thunder. I had never seen a comet before and was stunned. Hale-Bopp was a little better, but there’s nothing like your first time!

      • JimG1, yes, I observed Hale-Bopp w/a telescope in Virginia. Bright, but disappointed in its small size & short tail compared to the very long & ghostly Hyakutake, which when seeing I could almost understand the ancient people being mesmerized and maybe a bit scared.

  11. I’m trying to live to the age of a tad over 108 years. That will give me the opportunity to see Halley’s Comet (last predicted appearance date July 28, 2061), then have a year to talk about it.

    I am pretty sure I caught a glimpse of it during its disappointing 1986 appearance, but not entirely certain. Next time for sure.

  12. Looking forward to seeing my second comet with my naked eyes.
    (My first was Kohoutek. I was able to point it out to my Dad a few years before he died. I think it was his first.)

    • Kohoutek was my first and best. I had dark skies and a 3″ reflector. I was living in Seattle for Hale Bop and Hyakutake and could barely see either due to frequent overcast and light pollution.

  13. I took a moment to recognise comet Hyakutake when we went to look from our city’s dark south coast. After a moments gazing I realised the triangular shaped ‘mist’ covering half of the southern sky was actually the comet. We also saw Halley’s comet (not on the same night!) which I called “Halley’s blob and was a disappointment, at least in relation to the media’s hyping (or should I say ‘hyperbole).
    I am have been taking my vitamins in order to reach 106 years so I can see Halley’s again.

    • Perhaps that was why I was taken by Hyakutake so much — I lived at a very dark site & could appreciate it. One might hardly notice it in a light-polluted site. Plus, no telescope or binoculars was necessary or wanted — it was way too long and ghostly.

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