APOD: Four Billion BCE: Battered Earth (2014 Aug 05)

[APOD Robot]

Four Billion BCE: Battered Earth

Explanation: No place on Earth was safe. Four billion years ago, during the Hadean eon, our Solar System was a dangerous shooting gallery of large and dangerous rocks and ice chunks. Recent examination of lunar and Earth bombardment data indicate that the entire surface of the Earth underwent piecemeal upheavals, hiding our globe's ancient geologic history, and creating a battered world with no remaining familiar land masses. The rain of devastation made it difficult for any life to survive, although bacteria that could endure high temperatures had the best chance. Oceans thought to have formed during this epoch would boil away after particularly heavy impacts, only to reform again. The above artist's illustration depicts how Earth might have looked during this epoch, with circular impact features dotting the daylight side, and hot lava flows visible in the night. One billion years later, in a calmer Solar System, Earth's first supercontinent formed.

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[bystander]

http://asterisk.apod.com/viewtopic.php?t=33709

[geckzilla]

Pretty cool picture. Couple of things I wonder about: The lava... what's going on there? Seems like it is way too blurry and big. If the whole crust is glowing like that there's no way there's any water on it. Would also like to have seen more work done on the atmosphere.

[Nitpicker]

Pretty cool picture. Couple of things I wonder about: The lava... what's going on there? Seems like it is way too blurry and big. If the whole crust is glowing like that there's no way there's any water on it. Would also like to have seen more work done on the atmosphere.

Only parts of the crust are glowing in the dark. Not sure much atmosphere would be visible at this scale.

[ericchill]

Since the iron in the oceans hasn't been oxidized yet, shouldn't they be some shade of green?

[geckzilla]

Pretty cool picture. Couple of things I wonder about: The lava... what's going on there? Seems like it is way too blurry and big. If the whole crust is glowing like that there's no way there's any water on it. Would also like to have seen more work done on the atmosphere.

Only parts of the crust are glowing in the dark. Not sure much atmosphere would be visible at this scale.

Some of the crust is even glowing in the light. Anyway, the point is it doesn't look like lava at all. It looks like a strangely low resolution procedural texture. Atmosphere: There's not a single cloud during this epoch? And the atmosphere is so thin that the limb doesn't even show a hint of it? I'm not talking about the thickness of it viewed against space. I'm talking about the effect it has when viewed obliquely against the land.

[Nitpicker]

Pretty cool picture. Couple of things I wonder about: The lava... what's going on there? Seems like it is way too blurry and big. If the whole crust is glowing like that there's no way there's any water on it. Would also like to have seen more work done on the atmosphere.

Only parts of the crust are glowing in the dark. Not sure much atmosphere would be visible at this scale.

Some of the crust is even glowing in the light. Anyway, the point is it doesn't look like lava at all. It looks like a strangely low resolution procedural texture. Atmosphere: There's not a single cloud during this epoch? And the atmosphere is so thin that the limb doesn't even show a hint of it? I'm not talking about the thickness of it viewed against space. I'm talking about the effect it has when viewed obliquely against the land.

Yes, perhaps the clouds were omitted for clarity. I might also have expected to see some volcanic plumes. But I do see at least a hint of atmosphere at the limbs (the thin white ring).

Question: if the Moon was formed only half a billion years before this image, from the collision of a Mars sized object with Earth, how long did it take for the Moon and Earth to (re)acquire a roughly spherical shape?

[Ann]

Seeing an illustration like this one makes me wonder about how and when life arose on Earth. There must obviously have been times when the Earth was uninhabitable and barren. So when did the first life forms arise? Is it possible that life "has made several attempts" before gaining a firm foothold on the Earth? Could there have been life on Earth, which was all killed off by the terrible bombardment of asteroids that we are told about here, when the Earth's oceans would have been completely vaporized? And could life then have arisen all over again later on, from scratch? And could this life-and-death cycle even have repeated a few times before life finally won out?

Ann

[Nitpicker]

Seeing an illustration like this one makes me wonder about how and when life arose on Earth. There must obviously have been times when the Earth was uninhabitable and barren. So when did the first life forms arise? Is it possible that life "has made several attempts" before gaining a firm foothold on the Earth? Could there have been life on Earth, which was all killed off by the terrible bombardment of asteroids that we are told about here, when the Earth's oceans would have been completely vaporized? And could life then have arisen all over again later on, from scratch? And could this life-and-death cycle even have repeated a few times before life finally won out?

Ann

Yes, the life-and-death cycle could have repeated a few times before the current (wondrous) cycle, but the evidence for it was probably vaporized and/or buried. Ultimately, death will "win" here on Earth. Such is life.

[CLOX]

The moon was already formed and orbiting about 20,000 miles from Earth surface producing a significant ovoid shape to the earth. Add a speed of rotation of 2400 mph, the equator would bulge almost 10% out of spherical. So, your flat round earth needs some modification. Also, only 10% of the surface was land exposed above the waters. I tried to imagine the tidal waves with a close moon moving at 1.9 miles per second and almost no land to break agsinst. Kowabunga!

[neufer]

Since the iron in the oceans hasn't been oxidized yet, shouldn't they be some shade of green?

With the Earth that hot it would have to have been shrouded with clouds (like Venus) so who would know.

• But I was thinking of a plan
  To dye one's whiskers green,
  And always use so large a fan
  That they could not be seen.

[neufer]

The moon was already formed and orbiting about 20,000 miles from Earth surface producing a significant ovoid shape to the earth. Add a speed of rotation of 2400 mph, the equator would bulge almost 10% out of spherical. So, your flat round earth needs some modification.

The Moon is thought to have formed nearly 4.5 billion years ago and rapidly receded from the Earth due to strong tidal interaction.

Let us assume (conservatively) that it was about a quarter of it's current distance by 4.0 billion years ago:

<<The Moon is gradually receding from the Earth into a higher orbit, and calculations suggest that this would continue for about fifty billion years. By that time, the Earth and Moon would become caught up in what is called a "spin–orbit resonance" or "tidal locking" in which the Moon will circle the Earth in about 47 days, and both Moon and Earth would rotate around their axes in the same time, always facing each other with the same side.>>

The angular momentum of the Moon increases with the square root of the distance or the cube root of the period so at "spin–orbit resonance" the Moon will have (47/27.32)^(1/3) or ~ 6/5 its current angular momentum (and, essentially, all of the angular momentum of the Earth & Moon system). Hence, currently the Moon has 5 units of angular momentum compared to just 1 unit for the Earth (for a total of 6 units of angular momentum).

When the moon was a quarter of it's current distance it had about 5/(4)^(1/2) units of angular momentum compared to 7/2 units for the Earth (for a total of 6 units of angular momentum). At this time the oblateness of the Earth was about 0.2 (or twice that of Saturn today).>>

[Ron-Astro Pharmacist]

We may not have been able to see our own world form but one might ponder about the ability to detect such violent events and aftermaths on other worlds with sophisticated detection technology of the near and far future. Phew!! Just saying it might be fun to watch.

[Psnarf]

http://www.nature.com/nature/journal/v5 ... E-20140731

I don't have access to the full article, but it might be the case that four billion is a bit on the low end of the age guestimate.

[bystander]

http://www.nature.com/nature/journal/v5 ... E-20140731

I don't have access to the full article, but it might be the case that four billion is a bit on the low end of the age guestimate.

http://asterisk.apod.com/viewtopic.php?t=33709

[Byork]

an asteroid impact with the earth is comparable to a wedding with merging of two bodies and characteristic fireworks. the impact event adds new minerals and elements essential to development of eden like terrestrial worlds. the earth is an outstanding example of an eden world. there is also the developmental regimen of venus and mars. if venus developed a sufficiently dynamic atmospheric structure in the upper atmosphere heat from the sun would be dispersed and the dense lower atmosphere would be allowed to cool and condense. mars is a desert world but there is considerable water on the planet sufficient to support grassland and blueberries. since nasa forgot to include canisters of seed on the last mission to mars observation of biological activity will not be possible. years from now when the larger martian moon phobos merges with the parent planet a lot of things will change. the merge event will probably be an extended orbital decay of the moon resulting in a ring formation around mars and fiery descent of rock and debris onto the martian surface. phobos is thought to be a captured asteroid which somehow became a moon of mars. perhaps this is a general mechanism of planetary development - an asteroid is captured by a planet and eventually merges with it. the earth too captures asteroids.

[geckzilla]

Grass and blueberries would never* grow on Mars. There's not enough atmosphere or water even if the soil temperature is adequately warm at the equator. NASA didn't "forget" seeds. It was a deliberate decision to try to avoid spreading Earth life to Mars because we need to determine if there is some form of life already there. Kind of hard to do if you bring a bunch of single celled organisms over, which would be required for any kind of hypothetical Mars garden. There is a lot more to soil and plant growth than water.

*I'll discount this and say probably not in my lifetime, anyway. Not without a closely tended greenhouse.

[neufer]

Click to play embedded YouTube video.

Grass and blueberries would never* grow on Mars.

'Blueberries' on Mars!

[BMAONE23]

Grass and blueberries would never* grow on Mars.

'Blueberries' on Mars!

Blueberries for the Horta Culturist

Click to view full size image

[ta152h0]

Looks like Io today. I just read elsewhere ther was a huge upheaval on Io recently. Wonder if it got hit by something big instead of a giant volcano going off ruining the party.

[JohnD]

"Artist's impression" of the Earth 4 Billion years ago, but the 'continent' on the upper, sunlight hemisphere looks awfully like a pockmarked North America!

Go compare!
http://www.dreamstime.com/royalty-free- ... ge10111796

John

[ta152h0]

I would speculate the magma chamber under Yellowstone is one of those impacts not completely healed yet.

[Chris Peterson]

I would speculate the magma chamber under Yellowstone is one of those impacts not completely healed yet.

Such impacts heal quickly. There would be massive geological evidence of an impact at Yellowstone in the last few millions of years, which is how recent it would need to be.

[DavidLeodis]

If (as I assume it is) the main audience that APODs are aimed at is the interested but non-scientific public (like me) then It would have been useful if the definition of BCE had been given. According to a source that I found it stated "BCE is the abbreviation for Before the Common/Current/Christian Era". Which BCE is meant in the APOD title?

[bystander]

They are all equivalent, as is the historical designation BC (Before Christ).