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You don't mention that there will be issues with atmospheric seeing. To realize the potential of the telescope you'll need adaptive optics and I am not sure if the usual wavefront sensors will work well with a target like Moon.

The other comments have already answered the question, but I'm going to add in a bit of context that's really obvious, but rarely thought about and that is that the moon is massive.

We often think of the moon as quite small, because we see it in the sky all the time and it looks small. Then we get these really high resolution pictures of it, normally something you can't do at great distances. Which further increases the perception that the moon is quite small.

Truth is, the moon is huge. Compared to the Earth, it's small, but as a physical entity, it's pretty big. Now I'm saying all this to give some comparison to the main question.

This is the Tycho crater. It's not the biggest crater on the moon, but it is one of the most visually distinct in that you can easily see the edges of it. That crater looks fairly small, but is actually 83km in diameter. So if that's how small something 83km across looks, it puts into scale just how tiny something as small as a rocket/lander would be.

Yes, telescopes can magnify much more than that picture, but it gives a good sense of the scale of what you are actually trying to look at.

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Dry Valleys of Antarctica have not seen rain for nearly two million years.

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> So if we are still in an ice age, then the gradual increase in global temperatures is all part of that

For the last 10,000ish years the Earth has been in an interglacial, ie. the least cold stage of an ice-age. Glacial-interglacial cycles have been occurring for the last 2 million years or so, which is the Quaternary Ice Age.

The increasing global mean temperature in very recent times is on top of being in the warmest part of an ice age, it cannot be attributed to part of the natural cycle. The natural cycle would be due to start cooling sometime in the next few thousand years and transition back to a glacial episode. Anthropogenic warming has eliminated that possibility and the fear is that the Earth could exit Ice Age mode entirely and switch into hot-house mode with virtually no ice at the poles at all, correspondingly higher global sea levels and a lot more energy in the climate system for extreme weather events to become a regularity.

> So where do scientists draw the line between the global warming caused by humans, and the global warming that’s part of the natural cycle of things?

Somewhere around the year 1900. Take your pick, determining an exact date is a bit of a moot point by now.

As u/astrokiwi mentioned, the maximum resolution achievable by modern or near-future groundbased optical telescopes comes down to about 5-10m. Depending on the lander used this would be anywhere between 1 and 5 pixels of lander visible in the image. The Lunar Gateway might be a different story however, as it will be large enough that such a telescope might be able to discern some of its structure.

At the absolute most extreme, we might get some nice Northern/Southern Lights.

Basically, this gas is so thin that we would consider it a vacuum. It's only over millions of years and many light years of space that the number of collisions between particles adds up for it to start acting like a gas, so that it can carry shockwaves, soundwaves etc. But we're often talking about less than one atom per cubic centimetre, and it's not going to push the Earth at all as we pass through this wave.

Some of these particles may be charged, and drawn in by the Earth's magnetic fields towards the poles, and maybe contribute to the Northern/Southern Lights. I haven't done the maths to see if that would be a significant contribution compared to the constant wind of particles we get from the Sun though.

Maybe just barely!

The maximum possible resolution you can physically get depends on the size of the telescope. The next generation of ground-based optical telescopes will have mirrors around 30m in size. At the distance of the Moon, these could have a resolution of about 5 or 10 metres, if they have perfect optics. So you might be able to make out the lander as a fuzzy blob at the limit of resolution, but won't be able to see any astronauts, and definitely not any footprints. You'd really want something like a 200m telescope if you wanted down to 1 metre resolution.

Interferometry isn't the best thing to help here. While you can combine light from multiple telescopes separated by some distance to increase their resolution, this is really tricky to do with visible wavelengths, and you're limited to a small number of telescopes on the same site. What you end up with isn't quite an image as you don't have enough combinations of baselines between telescopes to get the full visual information. At lower wavelengths (e.g. radio) it becomes easier to do interferometry affordably with a large number of telescopes (possibly even spread over the world!), but longer wavelengths also inherently have a lower resolution, and you're often dealing with a much dimmer image - the Sun emits a lot of visible light, so most things in the solar system are brightest in the visible ranges.

Overall, to photograph the Moon (and many other solar system objects) you get much better resolution by sending a small telescope to orbit the Moon than building a big one on Earth.

> Goldschmidt classification is nowhere near absolute, which is why we can have gold in the crust.

I thought that’s more to do with the following factors:

(1) chemical bonding subtleties mean that partition coefficients are never perfectly into exclusively one phase or the other

(2) core formation is far from a perfectly efficient process with regards to taking certain elements from other layers — even if partition coefficients were perfectly weighted to siderophile, reactions don’t run to completion without being diluted or interrupted, not least because the Earth was not completely molten for very long (if at all).

(3) the crust today (particularly the continental crust) has been modified extensively since whatever was left behind immediately after core formation. Transport and concentration of certain elements from the mantle to the crust and into more localised bits of the crust to form ore deposits has had ~4 billion years of geological processing to occur.

(4) most of the gold that exists in the crust today is thought to have been delivered to the Earth from space after core formation — the late veneer hypothesis eg. Dauphas & Marty, 2002

Is the Goldschmidt classification really so lacking? I know it was developed a long time ago but i thought it was only ever meant to be a broad classification scheme? Seems to fo a good job of that and it does allow for elements to have mixed classifications.

So then there's parts of the universe currently that we will never see ever unless wormholes etc.

You've had lots of good discussions and good replies here, but it's still not clear if you're on board with this now(?).

I'll have crack but taking a wider view.

Newton came up with these laws to try to explain observations he'd made of the world around him.

He came up with words like mass, force, acceleration, momentum and then came up with some mathematical relations between them. These 'laws' allowed him to make predictions about the universe that were accurate.

Given that they were accurate, they were also useful! Hence they've been widely adopted.

None of us created the universe, none of us have a perfect understanding of how it works. Whatever is causing our universe to tick forward might not be using Newtonian dynamics at all.

There is no experiment we can do to prove that mass or forces exist. We can make observations that are consistent with Newtonian dynamics, but that doesn't make it universal.

In fact we know for a fact at astronomical length scales it isn't, because Newtonian dynamics makes incorrect predictions about the momvment of stars etc. (hello general relativity!).

We do, however, know these laws are often very useful at day-to-day length-scales.

So you can have your own theory that an object in motion tends to slow down, or requires something 'a force' to keep it in motion. But if you do, then you need to explain why satellites don't slow down in space and drop out of the sky. You need to explain why when I'm in my car on the motor-way, I don't feel the seat pressing into my back when I'm at constant speed.

On the flip side, your contention with Newtonian dynamics is that you have observed that objects in motion tend to slow down. Newtonian dynamics has an answer to that - in all these cases, there is an external force acting on the objects slowing them e.g. friction or wind resistance.

For me Newtonian dynamics, seems to provide a more complete picture of the world and does a better job explaining my observations. So, for now, I'm going to stick with using those rules to make predictions in my day-to-day.

Of course, it's a bit unintuitive this idea that objects at motion continue at motion... that's why Newton is widely considered to be a really really smart guy. He managed to get his head around that idea and ended up with a theory that made so many accurate predictions.

The real bursa equivalent is the spleen, where transitional B cell development occurs after central tolerance.

Dopamine: Supports feelings of reward and motivation. More Dopamine is produced in anticipation of something good.

Serotonin: Helps maintain emotions. This is why antidepressants (SSRI and SNRI) are designed to balance out serotonin levels.

Oxytocin: The “love” hormone, gives you a rush of pleasure from affection and connection.

Endorphins: A surge of pleasure, often in response to occasional discomfort or stress. Endorphins are endogenous opioids, so they bind to the opioid receptors. The runners high is thought to be as a result of a release of endorphins after a hard run.

Already great answers here, but I'll go back even further. OP might be referring to when things started with bilateral symmetry as a body plan. Right about 600 million years ago right before the Cambrian period. Before that, most everything was radial symmetry. Think sea anemone. Once bilateral started you started getting two eyes and all sorts of fun stuff. We go back a loooong way !

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Thank you for the advice, will do!

Your primary misunderstanding is that the past we are seeing into is not the past of “our part” of the universe.

The universe is likely infinite. The observable universe is a sphere with us in the middle. The edge of the sphere is where we see the oldest parts of the universe because the light from these distant places is just now reaching us, showing us what things looked like back then.

This sphere is getting bigger for an obvious reason, more and more light from distant places is reaching us. However, the sphere is also getting bigger because the entire universe (not just the observable universe sphere) is expanding.

Careful here not to imagine the entire universe’s expansion as a sphere, but rather every galaxy that isn’t locally bound to another galaxy by gravity is moving away from one another.

An oversimplified way to imagine this is to visualize an infinite 3D space with tennis balls each 10 meters from one another in every direction. Move forward through time and as the universe expands they are now 20 meters away from one another. Move back in time and they are 5 meters away from one another and so on.

The interesting thing is that, though the speed of light is constant, this expansion of the entire universe seems to happen faster with the more space that there is between things, as if the space itself was causing the expansion (we call this expansion Dark Energy).

What this means is that eventually the expansion of the entire universe will greatly outpace the speed of light, making galaxies we can currently see in the observable universe fade out of sight as they slip out of our observable universe. Eventually, only our own galaxy (at this point merged with Andromeda) and perhaps a few others in our local group will visible to us, everything else too far away and the universe expanding too fast for new light to reach us.

If humans still exist in this time, they would have no knowledge of other galaxies and the universe unless we managed to pass down the data from our time.

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These are called tetrapods, descendants of the lobe finned fish. We all share this body plan because afawk fish only made the change to fully terrestrial life once, and all living exclusive lung breathers are descendants of the species that did. Fun fact, this means that technically, whales actually are fish after all.

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