# Pluto vs Earth

**URL:** <https://boards.straightdope.com/t/pluto-vs-earth/768859>\
**Category:** Factual Questions\
**Created:** [October 17, 2016, 5:46pm UTC](https://boards.straightdope.com/t/pluto-vs-earth/768859 "2016-10-17T17:46:42Z")\
**Posts on this page:** 3\
**Page:** 3

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**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\
**Post date:** [October 20, 2016, 11:25am UTC](https://boards.straightdope.com/t/pluto-vs-earth/768859/41 "2016-10-20T11:25:58Z")

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But if you’re defining “bacteria” to include the archae, then it’s not a clade, either.

EDIT: Oh, and if you consider “archae” to be a clade, it’s the clade which includes all living things. So it’s trivial to say that it’s the age of archae.

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**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\
**Post date:** [October 20, 2016, 1:45pm UTC](https://boards.straightdope.com/t/pluto-vs-earth/768859/42 "2016-10-20T13:45:21Z")

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> [@dracoi](#):
>
> Even “lightly” placing Pluto’s surface against the Earth’s surface puts its center of mass 750 miles above the surface. So you still have a supersonic avalanche with the mass of a continent. There’s nothing gentle about that, and I suspect you’ll still end up with enough energy to create a fireball shockwave that will circle the globe.

By my rough back of the envelope calculation the potential energy involved is 100 times that necessary to melt the entire Earth.

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**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\
**Post date:** [October 20, 2016, 2:22pm UTC](https://boards.straightdope.com/t/pluto-vs-earth/768859/43 "2016-10-20T14:22:56Z")

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> [@Chronos](#):
>
> But if you’re defining “bacteria” to include the archae, then it’s not a clade, either.
> 
> EDIT: Oh, and if you consider “archae” to be a clade, it’s the clade which includes all living things. So it’s trivial to say that it’s the age of archae.

I don’t think you understand what a clade is. Or else you think that Archaea are ancestral to all living things.

There was a common ancestor to all living things, but it would not have been classified as Archaea, Bacteria, or Eucaryota. Archaea were a very early branch from that ancestral lineage, but they themselves are not ancestral to either Bacteria or Eucaryota.

Likewise the common ancestor of Archaea and Eucaryota would not have been either an archaean or a eucaryote.

The earliest split of the tree of life that we know of is between the sister-groups Bacteria and (Archaea + Eucaryota). Those two sister groups are valid groups for comparison.

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