In this post, I attempt to link what the C's said in this session about the speed of the comet cluster, with what is known about the speeds of known comets and their meteor streams. The cluster I'm referring to is the 3600-year cycle mentioned on many occasions. At the end, I wonder if cluster could also be clustering.
The speed of the incoming comet cluster according to the C's
From
this session:
A: Let us just say that the cluster travels much faster than the usual cometary itinerary.
Long-periodic comets have orbital times from around 200 to 1000 years. Comets with periods longer than 1000 years are listed as
near-parabolic comets. If this cluster reappears about every 3600 years then the comets must be near-parabolic comets.
The period of comets varies, and so do their speeds
The
Lunar and Planetary Institute has a page about
Impact Cratering Mechanics with illustrations designed for educational purposes. The first one shows that the speed of long-period comets is higher.
In the description, they explain:
The minimum velocity of objects impacting the Earth is ~11.2 km/s, which is equivalent to the escape velocity of the Earth. Asteroids, the most common type of impactor, slam into the Earth at an average velocity of 18 km/s. Short-period comet impacts with the Earth are less common, but have higher impact velocities averaging 30 km/s. Even rarer are impacts from long-period comets at higher impact velocities that average 53 km/s.
The speed of 53 km/s for long-period comets could be an average between 45 km/s and 70 km/s, weighted for frequency with slow being more common. There are objects faster than this, like the interstellar space rock
Oumuamua that moved at 83.7 km/s,
The described differences in speed between short and long period comets may be idealized and not hold in all cases. For instance the
55P/Tempel-Turtle Comet, a
short-period comet, mentioned in a German
list and this
Japanese, has of period of 33 years, but the speed is
close to 71 km/s. This is the same as for the meteor stream associated with Temple-Tuttle, the Leonid meteoroids, which "
are considered to be some of the fastest meteors out there." But is that speed an anomaly caused by factors in the space of its present orbit, or might and Tempel-Turtle originate from a faster and larger comet with a longer period? Is there something to the Temple.Tuttle and its Leonids along what Aristotle thought. In
article about the Great Leonids Meteor Storm of 1833, one finds:
Olmsted also overturned a 2,000-year-old doctrine developed by Aristotle that held that meteors were the fiery sparks of the remains of enormous gas bubbles that rose into the air, before exploding high above the ground.
If Aristotle had an idea that meteor streams could be a result of comets breaking up, then he was onto something. Olmsted's thinking was fine, but not the whole story.
The speed of some meteor streams associated with comets
If the Leonids are fast, what about others? I tried to look up a site on NASA Jet Propulsion Laboratory with
meteor streams to check if they were associated with comets. In some instances, yes, for others discoveries are waiting or their parent comet is long gone.
Next are a few examples of comets associated with streams and chosen from those with the longest orbits I could find in the list:
C/1739 K1 is a parabolic comet, and they don't give and orbit. If it has, it will be very long period, but it does have a stream, the
Leonis Minorids that move at 62 km/s
C/1911 N1 (Kiess) has a period of 2489 years and is associated with the
Aurigids. The
German Wiki is more informative and gives the speed as 66 km/s
C/1983 H1 (IRAS-Araki-Alcock) has a period of 970 years and is the parent of E
ta Lyrids with average speeds close to 44 km/s
C/1861 G1 (Thatcher) has a period of 415 years and gives rise to the April Lyrids, and they have speeds around 48 km/s
C/1979 Y1 (Bradfield) has a period of 307 years, and has given rise to the July Pegasids that moves at 65 km/s
The above examples indicate that the long-period and near-parabolic comets are in the fast lane; two-three or more times faster than the average impact speed on Earth, if the speeds of their meteor streams are reliable indicators of their own speed. Since only meteor streams in the
list from NASA have been assigned a comet, there is much to discover. Add to this that the NASA list of meteor streams is much shorter than this from
Universeguide.com
The 3600-year cluster and meteor streams
Perhaps one of the meteor streams not yet associated with a comet, or meteors not yet associated with a stream owe their existence to a comet cluster with a period of 3600 years. If there is an uptick in the number of observations of fast meteors, it could be an indication of a change in the cosmic environment. A difficulty with observing meteors precisely, is that the equipment has to very carefully set up. A small error can make a lot of difference when calculating the orbit and the period of the meteor.
A few known comets in the 3600-year league
Below are some examples from
the Wiki list of near-parabolic comets with periods of 3600 years ±100 years. The name of the comet is to the left, the period to the right. For other explanations, see the link above.
Could cluster also mean clustering?
When one considers an orbit of 3600 years then a cluster may mean not all at one time, but close together, or within a few years. Another possibility is that there is a rhythm to the appearance of comets, that creates a clustering effect of comets from all over the place at regular intervals, similar to how some muscles of a heart contracting come closer together. If one can observe structures and beauty in a
Mandelbrot set, or among numbers, why not unexpected patterns and structures in cosmic space and among comets. It is still possible we will be rather surprised.
