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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.
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.
originally posted by: intrptr
originally posted by: TrueBrit
a reply to: swanne
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.
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.
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.
That doesn't make any sense because it sounds like you think the galaxy is still and we are the only thing moving.
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.
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.
originally posted by: wildespace
a reply to: MysterX
The "regions of space" outside of stellar systems are very, very, extremely empty.
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:
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 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.”
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.
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.
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.
Yes the bombardment coming from within is far more likely.
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.