[Rockhounds] Astronomers: A comet fragment, not an asteroid, killed off the dinosaurs

[Tim Fisher]

I saw this theory on some science TV show or another, it was probably a
way-out-there proposition back then. Good to see someone backed it up :)

Tim Fisher
Http://OreRockOn.com 
Email nospam at orerockon.com

-----Original Message-----
From: Rockhounds [mailto:rockhounds-bounces at rockhounds.drizzle.com] On
Behalf Of Kreigh Tomaszewski
Sent: Monday, February 15, 2021 5:50 PM
To: Rockhounds at drizzle.com: A mailing list for rock and gem collectors
Subject: [Rockhounds] Astronomers: A comet fragment, not an asteroid, killed
off the dinosaurs

Jupiter's gravity pushed comet toward Sun; comet was ripped apart by tidal
forces.
Some 66 million years ago, a catastrophic event occurred that wiped out
three-quarters of all plant and animal species on Earth, most notably taking
down the dinosaurs. An errant asteroid from the asteroid belt
<https://en.wikipedia.org/wiki/Asteroid_belt> has been deemed the most
likely culprit. However, in a new paper
<https://www.nature.com/articles/s41598-021-82320-2> published in Scientific
Reports, Harvard astronomers offer an alternative: a special kind of comet—
originating from a field of debris at the edge of our solar system known as
the Oort cloud
<http://their%20findings%20also%20offer%20evidence%20that%20the%20unusual%20
composition%20of%20the%20chicxulub%20impactor%E2%80%94carbonaceous%20chondri
te%E2%80%94indicates%20it%20originated%20from%20the%20oort%20cloud%2C%20and%
20not%20from%20the%20main%20asteroid%20belt%2C%20as%20suggested%20by%20one%2
0of%20the%20more%20popular%20origin%20theories.%20it%27s%20a%20rare%20compos
ition%20for%20main-belt%20asteroids%2C%20but%20common%20among%20long-period%
20comets.%20the%20authors%20also%20point%20to%20other%20impact%20craters%20w
ith%20similar%20composition%2C%20most%20notably%20the%20vredefort%20crater%2
0in%20south%20africa%E2%80%94the%20result%20of%20an%20impact%20some%202%20bi
llion%20years%20ago%E2%80%94and%20the%20zhamanshin%20crater%20in%20kazakstan
%2C%20from%20an%20impact%20within%20the%20last%20million%20years.%20those%20
times%20frames%20are%20in%20line%20with%20siraj%20and%20loeb%27s%20calculati
ons%2C%20which%20indicate%20such%20objects%20should%20strike%20earth%20once%
20every%20250%2C000%20to%20730%2C000%20years./>—that
was thrown off course by Jupiter's gravity toward the Sun. The Sun's
powerful tidal forces then ripped pieces off the comet, and one of the
larger fragments of this "cometary shrapnel" eventually collided with Earth.
https://arstechnica.com/science/2021/02/astronomers-a-comet-fragment-not-an-
asteroid-killed-off-the-dinosaurs/
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