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RE: [comets-ml] Can someone explain orientation of Lulin's 2 tails?

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  • kronk@cometography.com
    Hi Bob, What I keep thinking when I visualize comet Lulin is look at a picture of comet West and tilt it. Sound strange? Let me try explaining and, please,
    Message 1 of 3 , Feb 23, 2009
      Hi Bob,

      What I keep thinking when I visualize comet Lulin is look at a picture
      of comet West and tilt it. Sound strange? Let me try explaining and,
      please, anyone, make corrections if I am visualizing incorrectly here.

      We know that the gas and dust is blown away from a comet by the solar
      wind. In general, the majority of the gas and dust stays in the plane of
      the comet. The tiny gas molecules of the ion tail very rapidly move away
      from the sun in a straight line. The larger dust particles don't move
      away from the sun as quickly. With the comet moving forward in its
      orbit, the dust tail inevitably appears to curve back.

      With comet Lulin, the orbital plane is basically aligned with our line
      of sight. Since Earth is between the sun and comet, all of the gas and
      dust is being blown away from us. As the comet approached us, we have
      been seeing the gas tail on the west side of the comet moving directly
      away from the sun, but with the comet moving westward, all of the dust
      is moving away from us and trailing off to the east. So, the dust
      appears as an "anti-tail" pointing toward the sun, where, in fact, it is
      all within are arced cloud steadily drifting away from the sun and us.

      What lies ahead? The gas tail will become more compressed and may be
      lost behind the comet. As the comet continues moving away from us the
      gas tail may start showing up on the west side. The dust tail should
      continue appearing long, straight, and extending west of the comet. With
      the comet rapidly moving westward, the "anti-tail" will magically become
      the "normal" tail without ever changing direction.

      I hope this helps to visualize this comet better. Going back to comet
      West, its orbital plane was basically perpendicular to our line of
      sight. For comet Lulin, its orbital plane is parallel to our line of
      sight.

      Sincerely,
      Gary

      > -------- Original Message --------
      > Subject: [comets-ml] Can someone explain orientation of Lulin's 2
      > tails?
      > From: Bob King <nightsky55@...>
      > Date: Mon, February 23, 2009 7:06 pm
      > To: comets-ml@yahoogroups.com
      >
      >
      > Hi fellow comet observers,
      > I'm trying to create a diagram showing the actual orientation of Comet
      > Lulin's two tails in space this week. While I understand that the ion
      > tail points directly away from the sun, does anyone know the true
      > angle of the dust tail? How much of the dust tail is trailing debris?
      > And why does none of the dust tail appear to be pointing away from the
      > sun? Thanks a lot for your help on this!
      > Bob
    • Bob King
      Hi Gary, Thanks for taking a swing at this. I think I understand (mostly). So the dust tail has been and is still currently pointed at the sun because the
      Message 2 of 3 , Feb 23, 2009
        Hi Gary,
        Thanks for taking a swing at this. I think I understand (mostly). So
        the dust tail has been and is still currently pointed at the sun
        because the larger, slower-moving particles (compared to gas) fall
        behind the comet in the sun's direction?
        Bob

        On Mon, Feb 23, 2009 at 8:35 PM, <kronk@...> wrote:
        > Hi Bob,
        >
        > What I keep thinking when I visualize comet Lulin is look at a picture
        > of comet West and tilt it. Sound strange? Let me try explaining and,
        > please, anyone, make corrections if I am visualizing incorrectly here.
        >
        > We know that the gas and dust is blown away from a comet by the solar
        > wind. In general, the majority of the gas and dust stays in the plane of
        > the comet. The tiny gas molecules of the ion tail very rapidly move away
        > from the sun in a straight line. The larger dust particles don't move
        > away from the sun as quickly. With the comet moving forward in its
        > orbit, the dust tail inevitably appears to curve back.
        >
        > With comet Lulin, the orbital plane is basically aligned with our line
        > of sight. Since Earth is between the sun and comet, all of the gas and
        > dust is being blown away from us. As the comet approached us, we have
        > been seeing the gas tail on the west side of the comet moving directly
        > away from the sun, but with the comet moving westward, all of the dust
        > is moving away from us and trailing off to the east. So, the dust
        > appears as an "anti-tail" pointing toward the sun, where, in fact, it is
        > all within are arced cloud steadily drifting away from the sun and us.
        >
        > What lies ahead? The gas tail will become more compressed and may be
        > lost behind the comet. As the comet continues moving away from us the
        > gas tail may start showing up on the west side. The dust tail should
        > continue appearing long, straight, and extending west of the comet. With
        > the comet rapidly moving westward, the "anti-tail" will magically become
        > the "normal" tail without ever changing direction.
        >
        > I hope this helps to visualize this comet better. Going back to comet
        > West, its orbital plane was basically perpendicular to our line of
        > sight. For comet Lulin, its orbital plane is parallel to our line of
        > sight.
        >
        > Sincerely,
        > Gary
        >
        >> -------- Original Message --------
        >> Subject: [comets-ml] Can someone explain orientation of Lulin's 2
        >> tails?
        >> From: Bob King <nightsky55@...>
        >> Date: Mon, February 23, 2009 7:06 pm
        >> To: comets-ml@yahoogroups.com
        >>
        >>
        >> Hi fellow comet observers,
        >> I'm trying to create a diagram showing the actual orientation of Comet
        >> Lulin's two tails in space this week. While I understand that the ion
        >> tail points directly away from the sun, does anyone know the true
        >> angle of the dust tail? How much of the dust tail is trailing debris?
        >> And why does none of the dust tail appear to be pointing away from the
        >> sun? Thanks a lot for your help on this!
        >> Bob
        >
        >
      • kronk@cometography.com
        Thanks for clarifying some of my points Michael! So, Bob, the anti-tail is only apparently pointing toward the sun, but not actually pointing toward it. As
        Message 3 of 3 , Feb 24, 2009
          Thanks for clarifying some of my points Michael!

          So, Bob, the anti-tail is only apparently pointing toward the sun, but
          not actually pointing toward it. As Michael indicated, it is only a
          matter of perspective.

          Sincerely,
          Gary

          > -------- Original Message --------
          > Subject: Re: [comets-ml] Can someone explain orientation of Lulin's 2
          > tails?
          > From: "Michael Mattiazzo" <mmatti@...>
          > Date: Tue, February 24, 2009 3:52 am
          > To: <comets-ml@yahoogroups.com>
          >
          >
          > Hello Bob,
          >
          > The dust tail "pointing" at the Sun is merely a perspective effect. None of the particles are truly directed sunward.
          > The dust tail will appear to increase in length this week as the viewing angle improves.
          > Once comet Lulin passes opposition on Feb 26, the dust tail will magically appear to point away from the Sun, thus the term "anti-tail" should no longer be used on this list :)
          >
          > The ion tail will disappear behind the comet at opposition, since it will then point directly away from Earth and Sun
          > Afterwards, it will start to merge with the dust tail in PA 110 degrees (ESE), but the dust tail will appear considerably brighter.
          > You can perhaps better visualise the orbit of comet Lulin using the following orbit viewers.
          > It helps to look at the orbits from directly above the solar system:
          > Imagine the dust particles trailing behind the comet in its orbit, especially the largest particles which are deposited directly behind the comet.
          >
          > http://www.m-matsu.com/astro/OrbitViewer/comets.cgi
          > or
          > http://www.users.on.net/~dbenn/Astronomy/OrbitViewer/comet_ov.html
          >
          > Hope this helps.
          > cheers,
          > Michael Mattiazzo
          >
          >
          >
          >
          > ----- Original Message -----
          > From: Bob King
          > To: comets-ml@yahoogroups.com
          > Sent: Tuesday, February 24, 2009 2:56 PM
          > Subject: Re: [comets-ml] Can someone explain orientation of Lulin's 2 tails?
          >
          >
          > Hi Gary,
          > Thanks for taking a swing at this. I think I understand (mostly). So
          > the dust tail has been and is still currently pointed at the sun
          > because the larger, slower-moving particles (compared to gas) fall
          > behind the comet in the sun's direction?
          > Bob
          >
          > On Mon, Feb 23, 2009 at 8:35 PM, <kronk@...> wrote:
          > > Hi Bob,
          > >
          > > What I keep thinking when I visualize comet Lulin is look at a picture
          > > of comet West and tilt it. Sound strange? Let me try explaining and,
          > > please, anyone, make corrections if I am visualizing incorrectly here.
          > >
          > > We know that the gas and dust is blown away from a comet by the solar
          > > wind. In general, the majority of the gas and dust stays in the plane of
          > > the comet. The tiny gas molecules of the ion tail very rapidly move away
          > > from the sun in a straight line. The larger dust particles don't move
          > > away from the sun as quickly. With the comet moving forward in its
          > > orbit, the dust tail inevitably appears to curve back.
          > >
          > > With comet Lulin, the orbital plane is basically aligned with our line
          > > of sight. Since Earth is between the sun and comet, all of the gas and
          > > dust is being blown away from us. As the comet approached us, we have
          > > been seeing the gas tail on the west side of the comet moving directly
          > > away from the sun, but with the comet moving westward, all of the dust
          > > is moving away from us and trailing off to the east. So, the dust
          > > appears as an "anti-tail" pointing toward the sun, where, in fact, it is
          > > all within are arced cloud steadily drifting away from the sun and us.
          > >
          > > What lies ahead? The gas tail will become more compressed and may be
          > > lost behind the comet. As the comet continues moving away from us the
          > > gas tail may start showing up on the west side. The dust tail should
          > > continue appearing long, straight, and extending west of the comet. With
          > > the comet rapidly moving westward, the "anti-tail" will magically become
          > > the "normal" tail without ever changing direction.
          > >
          > > I hope this helps to visualize this comet better. Going back to comet
          > > West, its orbital plane was basically perpendicular to our line of
          > > sight. For comet Lulin, its orbital plane is parallel to our line of
          > > sight.
          > >
          > > Sincerely,
          > > Gary
          > >
          > >> -------- Original Message --------
          > >> Subject: [comets-ml] Can someone explain orientation of Lulin's 2
          > >> tails?
          > >> From: Bob King <nightsky55@...>
          > >> Date: Mon, February 23, 2009 7:06 pm
          > >> To: comets-ml@yahoogroups.com
          > >>
          > >>
          > >> Hi fellow comet observers,
          > >> I'm trying to create a diagram showing the actual orientation of Comet
          > >> Lulin's two tails in space this week. While I understand that the ion
          > >> tail points directly away from the sun, does anyone know the true
          > >> angle of the dust tail? How much of the dust tail is trailing debris?
          > >> And why does none of the dust tail appear to be pointing away from the
          > >> sun? Thanks a lot for your help on this!
          > >> Bob
          > >
          > >
          >
          >
          >
          > [Non-text portions of this message have been removed]
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