Comet Garradd Pays A Visit To A Herculean Star Cluster

Comet Garradd photographed this morning (Feb. 2) near the globular cluster M92 in Hercules. The dust tail points to the left (east) of the comet's bright center called the coma. The gas tail points to the upper right. Credit: Michael Jaeger

Binocular and telescope owners can watch a fine match-up of the sky’s current brightest comet – Comet C/2009 P1 Garradd – and the rich cluster M92 in Hercules tomorrow morning. The cluster belongs to an ancient group of spherical, star-packed clusters called globulars. Some 330,000 stars are jammed into a ball 109 light years in diameter 26,000 light years away. Despite that rather spectacular distance, it still shines brightly enough at magnitude 6.4 to be easily visible in a typical pair of binoculars from moderately light polluted skies. Look for a small fuzzy spot with a brighter center.

Comet Garradd will be another fuzzy patch only a half a degree to the right or west of M92, so both little glows will be close together in the same field of view in any pair of binoculars. As you’d expect, the comet is much closer to Earth at 142.8 million miles. The separation between them will increase in the coming mornings as Garradd tracks slowly northward through Hercules.

Garradd's two tails point away from each from a combination of the comet's location high above the plane of the planets and our perspective of it from Earth. Blue arrows show the direction the comet's moving along its orbit. Credit: NASA/JPL with my own additions

In the diagram above, you can see that the comet has a steeply inclined orbit that takes it well above the plane of the solar system where the planets orbit. That’s why we see it high in the northern sky this month far from the morning planets. Comets that pass relatively close to the sun typically develop two tails – one made of dust carried away by the pressure of sunlight along the comet’s orbit and an ion tail of gases that fluoresce when they’re excited by the ultraviolet energy in sunlight. The dust is released into space as the heat of the sun vaporizes cometary ices.

This map shows Comet Garradd in the coming 10 days as it glides through the constellation Hercules. Stars are shown to 8th magnitude. Click the image for another map showing how to easily find Hercules. Created with Chris Marriott's SkyMap software

Since ion tails always point directly away from the sun, while dust tails lag behind in the curve of a comet’s orbit, the two tails point in different directions. Depending upon the sun-Earth-comet viewing geometry, they sometimes overlap or appear separated from one another by varying degrees. Our current viewing angle – looking up from way down below Garradd’s orbit – accentuates the tails’ separation.

The best time to see Comet Garradd and M92 is about 1 1/2 – 2 hours before sunrise, when it’s highest in the eastern sky before morning twilight begins. A small telescope will show the bright coma and a hint of both tails; telescopes of 8 inches or larger will show both tails stretching faintly more than a degree from comet’s head. Seeing a pile of stardust right next to bright, nearby comet should make for a beautiful sight. Try to get out in the next few mornings before moonlight becomes a problem.

7 Responses

  1. Steve

    Wow, tell Michael Jaeger that he takes some impressive pictures. I’m still waiting for a clear night (when I’m NOT at work) to go out stargazing again. Hope to join you at the Planetarium tomorrow night, however! Have you seen Garradd recently?

    1. astrobob

      Hi Steve,
      Looks like it’ll be clear too on Saturday night. It’ll be great to have you there. Yes, I’ve seen Garradd. Looks great in the 15-inch — pale green coma and two nice tails.

  2. Mike

    I was out lastnight at 2am. And looking for gerrard. How much magnification do you neeed? I thought I found it but I didn’t see any coma or tail. More of a hazy ball/cloud. On the other hand holy Saturn! I forgot it was out so focused on the commet. I looked over at the bright object in the east BAM! Saturn and it’s rings.

    1. astrobob

      Hi Mike,
      Yes, your first impression would be of a hazy ball of light. With your size telescope at the lowest magnification you can get to, try using averted vision to see the tails. They’re very misty, like thick dim shaft of light “flowing” out of the coma. If they is any moonlight, they may be invisible for the time being.

  3. Nitesh

    I live in India. I saw a fireball like object on 6th February, 2012 just before sunrise. I was travelling in my car & it was visible for nearly one hour after the sunrise too. Was it comet Garradd or anything else?
    I would be really grateful if you reply me on my mail.

  4. christine

    I saw a ‘comet’ on 6 February 2012 at 6.45 am in Toronto, Ontario.
    (First one I have ever seen)
    It was in the eastern sky heading in a southerly direction toward Lake Ontario.
    Bright green tail.

    I note several posts on other sites from others who also spotted it that morning.

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