We have meteorites from Mars but...

[Ags]

... do we have any meteorites from Earth? I was thinking they could be very interesting time capsules from our distant past, perhaps containing bubbles of archaic atmosphere, or re-infecting us with long-extinct strains of bacteria

[Alien 13]

Nice idea, I do also wonder why we have lots of Mars meteorites but none or very few from Venus.

Alan

[Subdeo]

@ alien 13:

Here are a few reasons that we have no Venusian meteorites that I found on CloudyNights by Peter Scherff:

Venus has greater gravity than the parent body of any meteorite.

The Sun’s gravity would pull any such meteorite away from Earth.
The atmosphere on Venus is a much more effective shield against meteorite impact than any other meteorite parent body has.
Any rock being blasted off of the surface of Venus would have to travel through that same thick atmosphere.

[Islander]

We have tektites, which consist of material ejected from the Earth's surface by impactors and then returned by gravity.

[John]

44 minutes ago, Islander said:

We have tektites, which consist of material ejected from the Earth's surface by impactors and then returned by gravity.

Yes, that is what I was going to post. Possibly other impactites such as Libyan Desert Glass and Moldavite as well ?

The possible origin of the angrite meteorite group was once thought to include Venus but I believe Mercury is considered a much stronger candidate now.

I've often wondered why quite a lot more meteoiric material of martian origin has been found compared with that of lunar origin with the Moon much closer to us ?

[LukeSkywatcher]

22 hours ago, Ags said:

... do we have any meteorites from Earth? I was thinking they could be very interesting time capsules from our distant past, perhaps containing bubbles of archaic atmosphere, or re-infecting us with long-extinct strains of bacteria

OK, thats it. I am getting rid of my Mars rock. I dont want any alien virus.

[LukeSkywatcher]

22 hours ago, Islander said:

We have tektites, which consist of material ejected from the Earth's surface by impactors and then returned by gravity.

Good point. I was thinking of something like that. Surely they would just be made up of the same stuff we see all around us today (different types of rock).

[Islander]

Tektites tend to be more like a glass.  They're formed from the ejecta of a large impact with the high energy yield and pressure and temperatures that that implies - normal rock simply won't survive that unchanged.  John mentioned Moldavites which have the appearance of a beautiful green patterned glass and are thought to originate from the Nordlinger Ries impact crater in Bavaria.  I have some Indochinite tektites which have a black glassy appearance similar to weathered obsidian.

[LukeSkywatcher]

Tektites, whilst beautiful, basically are GLASS. I dont have any interest in them. Strictly speaking they are not "meteorites" as they were formed here on Earth from an impact and those high temps/pressure.

I prefer to collect something which i know to be the leftovers of the formation of the planets.

 

[Islander]

Fair enough but they're still objects that have been ejected from the Earth by an impact, and then returned by gravity albeit on a short time scale.  They're a record of a cataclysmic event.  Mars and Moon meteorites are also produced by and are records of cataclysmic events.  It depends on viewpoint I suppose.

[Stub Mandrel]

23 hours ago, John said:

I've often wondered why quite a lot more meteoiric material of martian origin has been found compared with that of lunar origin with the Moon much closer to us ?

Perhaps moon rock is too similar to earth rock?

[John]

Sorry - posted in error !

(just trying boost my post count)

Actually I did find this link which might be of interest:

http://meteorites.wustl.edu/lunar/howdoweknow.htm

 

[LukeSkywatcher]

10 minutes ago, John said:

difference between lunar rock and earth rock

 

Apparently so. The thinking was that that the Moon was formed from Earth material after a big impact of a planetary body. This seems not to be the accepted theory now because the composition of Earth rock and Moon rock is quite different.

The Moon therefor must be made up more from the impactor............whatever that was.

 

[Gina]

They said said the opposite on The Sky at Night t'other day.  Moon rock was virtually identical to earth rock and this disproved the theory of collision of another object hitting the earth and creating the moon.  The conclusion was that the earth and moon were created at the same time from the same material.

[Shibby]

What Gina said.

The other possibility IIRC was that the impactor was much bigger than predicted and vapourised the whole Earth, from which the Moon and Earth 2.0 formed.

I believe that geologists are already able to recover samples of the Earth's prehistoric atmosphere and chemical makeup from ancient rocks and core samples, so there's not really a need for asteroids for this.