A Volcanic Comet Blows its Top

Posted: October 16, 2021 by oldbrew in Astrophysics, solar system dynamics, volcanos

But what kind of volcanoes? One researcher has a theory.


Oct. 14, 2021: So you think you know what a comet is? Think again. Comet 29P/Schwassmann-Wachmann is challenging old ideas. Astronomers call it a comet, but, really, “giant space volcano” might be a better description. It’s a 60-km-wide ball of ice orbiting the Sun beyond Jupiter, and it appears to be one of the most volcanically active bodies in the entire Solar System.

Comet 29P just blew its top … again. In late September 2021, 29P erupted 4 times in quick succession, blowing shells of “cryomagma” into space. Arizona amateur astronomer Eliot Herman has been monitoring the debris:

“Initially it looked like a bright compact object,” says Herman. “Now the expanding cloud is 1.3 arcminutes wide (bigger than Jupiter) and sufficiently transparent for background stars to shine through.”

When this object was discovered in 1927, astronomers thought they had found a fairly run-of-the-mill comet, unusual mainly because it was trapped…

View original post 434 more words

  1. JB says:



    Eyes to see, but in seeing, see not. Ears to hear, but in hearing, hear not. An intellect to perceive, but in thinking, comprehend not.

    Most days I wonder if Astronomy will ever come out of the Dark Ages.

  2. Gamecock says:

    From their description, it sounds more like a burp than a volcano.

    But that headline would be problematic.

  3. oldbrew says:

    The comet is unusual in that while normally hovering at around 16th magnitude, it suddenly undergoes an outburst. This causes the comet to brighten by 1 to 5 magnitudes.[5] This happens with a frequency of 7.3 outbursts per year,[5] fading within a week or two. The magnitude of the comet has been known to vary from 18th magnitude to 10th magnitude, a more than thousand-fold increase in brightness, during its brightest outbursts. On 14 January 2021, an outburst was observed with brightness from 16.6 to 15.0 magnitude, and consistent with the 7.3 outbursts per year noted earlier.[6] Outbursts are very sudden, rising to maximum in about 2 hours, which is indicative of their cryovolcanic origin; and with the times of outburst modulated by an underlying 57-day periodicity possibly suggesting that its large nucleus is an extremely slow rotator.

    – – –
    29P orbits twice per Saturn orbit (421:210 ratio is more exact).

  4. oldbrew says:

    The British Astronomical Association (BAA) is reporting another strong outburst of Comet 29P/Schwassmann-Wachmann. The volcanic comet suddenly brightened 10-fold on Oct. 23.75 UT when a sunlit vent opened, spewing ‘cryomagma’ into space.
    . . .
    Comet 29P is one of the strangest objects in the solar system. In fact, it strains the definition of “comet.” 29P is a ball of ice 60 km wide (much larger than a typical comet) trapped in a planet-like orbit between Jupiter and Saturn. It appears to be festooned with ice volcanoes which erupt ~20 times a year.
    . . .
    29P rotates once every ~58 days. As sunlight sweeps across its frozen surface, cryovolcanoes erupt under the high sun. “The latest eruption has taken place some 59 days after a similar event on August 25th, and may be an example of an outburst from the same cryovolcano erupting a second time on the next rotation of the nucleus,” says Miles.


  5. oldbrew says:

    Ongoing updates here…

    By Richard Miles

    STOP PRESS: Hubble Space Telescope observed 29P on October 26 16:01-18:20 UT