The Moon's surface is 100 times younger than previously thought

a reply to: Arbitrageur

What I do know is that the moon has the second lowest albedo in the solar system of all the known planets, dwarf planets, and moons, which doesn't tend to support that the albedo is getting higher when it's so low.

Perhaps, but then, the Moon is also quite young of a celestial body.

I don't expect to see much change in the subsequent 81,000 year periods, since most of what's happening is the mare material getting redistributed, and maybe the powder is getting covered with more powder so the powder is thicker, but the powder wouldn't be a significantly different color because the impactor debris is so small relative to the maria debris.

"Redistributed" is actually exactly what I have in mind. Dust from either impactors or kicked from brighter areas would settle on the basaltic areas, and pulverised balsat would settle on brighter areas. That is, in my opinion, a fair assumption. It does imply that the Moon's dark / bright zones change distribution over time, which is basically the crux of the debate we've been having.

originally posted by: intrptr

originally posted by: TrueBrit
a reply to: swanne

Query...

Do the calculations that were done to come up with this alteration in surface age, account for the fact that we are headed through a generally busier patch of space, with regard to space rocks and so on?

Most of the stuff that whizzes around inside the solar system is leftover from the formation. Not sure how they gauge what comes into our stellar shooting gallery from outside.

NASA

We don't just orbit our Sun, our entire Solar system orbits the Galactic centre...we are now in a 'patch of space' that our solar system has not been in for around 226 million years, the time it takes for us to make one orbit around the Galaxy.

It may be interesting to note, that roughly speaking, give or take a few million years, our planet suffered two of the worst extinction level events to occur here.

The Triassic - Jurassic event, around 201 million years ago (up to 75% of all species died off)
The Permian - Triassic event, around 250 million years ago.(up to 90% of all species died off)

So, it's not just rocks from the Asteroid belt or from the Oort cloud we need to be aware of...it's also the rocks we might encounter that are scattered along the path of our Galactic orbit.

originally posted by: swanne
a reply to: TrueBrit

The Solar System is relatively contained. Most of the meteor showers we receive, for instance, come from periodic comets that orbit our Sun. We aren't really heading into a patch of space full of rocks, not that I know of. The only way for us to get more rocks in our solar system would be to run into an alien solar system, which would kind of be noticeable.

So I'd say that the rate of meteor showers in recent history would be pretty constant.

www.cbsnews.com...
I hate commercials and I apologize because the video has one at the beginning.

Blinking is still used to detect the near earth objects (NEOs) that we have been able to detect. Pretty good video of the last one that blew up over Russia and people getting knocked off their feet and hurt with flying debris.
Objects over 1/2 mile wide astronomers now claim they have found approximately 95% ...Margin of error?

However there are 10,000 lesser objects we also know about.. It is pointed out in this video that the 10,000 they claim to know about in reality is about 1/2 of one percent guesstimated; in other words over one million are actually NEOs. Some pretty good graphics of the solar system so the video is worth a look IMO. Surprised we are not hit more often; just goes to show space, the final frontier is big with allot of space err room.....

With all the spectacular meteors we have had this year and the ATS threads about the events there might be some who are interested and enjoy the vid.
www.abovetopsecret.com...

a reply to: MysterX

The primary threat is from objects already trapped in orbit about the sun. Even those odds are very remote.

Like you said one or two extinction level events per billion-num.

The formation of objects occurs around stars, but I could be mistaken. Got a link to a sizable object that is known to be from outside?

a reply to: intrptr

No, no links...the thing is, there are no records existing (of course) that detail what is or could be lurking in this region of space. It is a tough enough job for us to catalogue actual planetary bodies and large asteroids in our own little Solar system, so for us to know what could be waiting for us, coming towards us, or is about to broadside our system, if anything, is next to impossible right now.

What is thought to be highly likely though, is the phenomena of so-called 'orphan' or 'wandering' planets or moons...having been ejected from their parent systems by some encounter or energetic event, is is thought there could be billions of these 'orphans' roaming around the Galaxy, separated from their parent stars...if one or more of these is in our orbital path..it's would probably be game over for all life here.

I listed the extinction events not as a 'scare / doom' thing, but to highlight that the last time our system was in this approximate region of the Galaxy, we were hit...and hit hard, nearly ending life here.

Now...whether those hits came from within or outside of the solar system is unknown, it's just as possible they came from outside as inside.

Cheers.

a reply to: MysterX
The "regions of space" outside of stellar systems are very, very, extremely empty. Asteroids and planets form around a star, and that's where they stay, unless there's some very massive body that flew by and gravitationally kicked them out of their system.

The biggest threat for our Solar System from the "outside" is any star that passes by very close; in that case it can disturb comets in the Oort cloud and send some on the collision course with Earth.

originally posted by: MysterX

Now...whether those hits came from within or outside of the solar system is unknown, it's just as possible they came from outside as inside.

As wildespace indicated, it probably is not "just as possible" for most of the bombardment of the Moon (and Earth, for that matter) to be from materials that had come from outside the solar system; it seems more likely to have come from within.

We can see a lot of asteroids and comets flying around the solar system that is gravitationally bound to the Sun -- i.e., part of the solar system. We have also studied meteorites that have impacted Earth. These materials seem to be what our solar system is built from, making it seem likely that these objects were the stuff that existed in the protoplanetary cloud that eventually became our solar system.

originally posted by: MysterX
I listed the extinction events not as a 'scare / doom' thing, but to highlight that the last time our system was in this approximate region of the Galaxy, we were hit...and hit hard, nearly ending life here.

That doesn't make any sense because it sounds like you think the galaxy is still and we are the only thing moving.

Our "approximate region" of the galaxy is rotating around the galaxy right along with us for the most part. The stars slightly closer to the center take a little less time to make one revolution around the milky way because they don't have as far to go and converse for the stars a little further from the center than ours, but the stars at the same distance from the center as us are probably orbiting at speeds very similar to our own.

originally posted by: wildespace
a reply to: MysterX
The "regions of space" outside of stellar systems are very, very, extremely empty.

Very true and this is why even if there are rogue planets zooming around which there probably are, they will likely miss our tiny solar system entirely. In fact if we want to examine sort of a worst case scenario of collision probabilities, imagine the entire milky way galaxy colliding with the entire Andromeda galaxy which will probably happen in a few billion years. There are expected to be very few collisions of any actual stars or planets when the galaxies collide. The central black holes should merge eventually but very few collisions are expected for the remainder of the galaxies due to these vast spaces.

Asteroids and planets form around a star, and that's where they stay, unless there's some very massive body that flew by and gravitationally kicked them out of their system.

Some stay but it's unlikely they all stay, and in fact there may have been as many as 30 proto planets in our early solar system (wikipedia says maybe over 100 so 30 is conservative). We only have 8 left, so where did they all go? The planet Theia collided with Earth to form the moon and maybe some others collided but others were likely ejected in a manner similar to what's seen in this simulation of solar system formation:

Planetary System Formation Simulation (200 AU View)

That shows how a number of rogue planets were ejected from the simulated solar system as it formed.

It's really hard to see objects even in our own Kupier belt and oort cloud so it's even harder to see rogue planets at much greater distances, but we think they are out there in significant numbers and I think simulations such as that make this speculation by Phil Plaitt plausible:

Scientists Get The Best Look Yet at a Rogue Planet With No Star

The researchers are careful to caution that this is still a rogue planet “candidate,” but even so, its existence wouldn’t be particularly surprising. According to Bad Astronomy blogger Phil Plait, “free-floating planets in the Milky Way may outnumber planets orbiting stars, and even be more numerous than stars themselves.”

But even if there are more rogue planets than planets orbiting stars, they are unlikely to pose much of a threat due to the vast spaces previously mentioned:

thecore.uchicago.edu...

Astronomers have long theorized that a planet could be ejected from its home solar system after its orbit was altered by the gravity of a nearby larger planet or another star. These “rogue planets” would then travel through space alone; the vast distances between stars virtually ensure the planets would never enter the orbit of another sun.

The biggest threat for our Solar System from the "outside" is any star that passes by very close; in that case it can disturb comets in the Oort cloud and send some on the collision course with Earth.

It's hard to say. A star would definitely be a bigger threat because its great mass can affect orbits without colliding with anything, however there are probably a lot more rogue planets than stars so from sheer numbers we might be more likely to encounter a rogue planet than a star, though such an encounter would tend to be less devastating and a rogue planet with the mass of Earth could potentially pass through our entire solar system without causing any significant disruption.

originally posted by: Box of Rain
As wildespace indicated, it probably is not "just as possible" for most of the bombardment of the Moon (and Earth, for that matter) to be from materials that had come from outside the solar system; it seems more likely to have come from within.

Yes the bombardment coming from within is far more likely.