Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

sgl_imaging_challenge_banner_comet_46p_winners.thumb.jpg.b3d48fd93cbd17bff31f578b27cc6f0d.jpg

Mick UK

why are there more impact craters at the top and bottom of the moon than .....

Recommended Posts

More recent volcanic eruptions re-paved those areas and "erased" the craters that ware there.

Share this post


Link to post
Share on other sites

Thanks for that pvaz, i suppose it now begs the question, why was there only volcanic eruptions around the middle of the moon and not the top and bottom!;):D

Share this post


Link to post
Share on other sites
Thanks for that pvaz, i suppose it now begs the question, why was there only volcanic eruptions around the middle of the moon and not the top and bottom!:p:D

Hehe! I'm clueless. Whe need Thalita here! She's the lunatic! :D

Share this post


Link to post
Share on other sites

.... why are there no 'maria' on the back of the moon..... time to dig out the copy of Charles Wood's book or go read the Geological History of the Moon again.

Cheers

PEterW

Share this post


Link to post
Share on other sites

Yep, i'm a lunatic and proud of it. :D

When large impactors hit the Moon they actually cracked the crust and allowed lava to flow up and fill in lower areas. Seeing as the impactors punched the crust down so much, it's logical that the pole areas remained higher in elevation and remained unflooded for the most part.

The large Mare Imbrium was from a huge impact and there are theories of an even larger one calld (iirc?) Gigantus or something like that.. you can see the huge rounded outline of it defined by the western shores of Oceanus Procellarum.

Regarding the large marias on the near side, i seem to recall reading that it was because that half's crust was thinner during the 'great bombardment'. The crust was thinner because the underlying lava fields melted the crust from the inside. When the impactors hit, the crust easily cracked and allowed the lava to flow out.

Mare Orientale is the result of a huge impact on the far side, but as you can see, the lava was contained within the circular rebound mountain chains of Rook and Cordillera.

Edited by Talitha

Share this post


Link to post
Share on other sites

I had heard somewhere that Earth had an influence on volcanic activity and that is why Mares are mostly on the near side where Earth had more influence, is there any truth to this at all then? I'd wonder if the Moon was even tidally locked to us back then or not.

Share this post


Link to post
Share on other sites
I had heard somewhere that Earth had an influence on volcanic activity and that is why Mares are mostly on the near side where Earth had more influence, is there any truth to this at all then? I'd wonder if the Moon was even tidally locked to us back then or not.

Thats correct.:D

Share this post


Link to post
Share on other sites

Thank you for that Talitha, very interesting...those poor Clangers, first they get bombarded by asteroids, then they are swamped by hot Lava..no wonder they are extinct:sad:

Edited by Mick UK

Share this post


Link to post
Share on other sites

When the Moon finally breaks away from Earths gravity/orbit does that mean that our seas will cease to have high/low tides?.

Share this post


Link to post
Share on other sites
When the Moon finally breaks away from Earths gravity/orbit does that mean that our seas will cease to have high/low tides?.

The sun also causes tides (half the force of the moon due to the distance). The largest high tides are caused when they are aligned.

As to the moon breaking away, that won't happen as the sun will die 1st.

Share this post


Link to post
Share on other sites

Thanks Paulo. I was under the impression that the Moon will only orbit Earth for another few million years before it is too far away to be held by earths gravity and go off on its merry way wandering through the solar system. Whereas the Sun is gonna be around for a few BILLION yrs more before it dies.

Share this post


Link to post
Share on other sites
Thanks Paulo. I was under the impression that the Moon will only orbit Earth for another few million years before it is too far away to be held by earths gravity and go off on its merry way wandering through the solar system. Whereas the Sun is gonna be around for a few BILLION yrs more before it dies.

Due to a combination of tides and the Earth's rotation, the Moon currently is moving away from the Earth at the rate of about 4 centimetres per year, but this rate is gradually slowing down. The rate of rotation of the Earth also is slowing down gradually. Eventually, things will reach an equilibrium. The Earth-Moon distance and the rate of rotation of the Earth will both remain constant. When this happens, the length of a day for Earth will be the same as the time the Moon takes to orbit once. The Moon remain at a fixed position in our sky!

If I can find an appropriate image and if anyone is interested, I can try to explain why tides cause the Earth-Moon distance to increase, and cause the Earth's rotation rate to decrease.

Edited by George Jones

Share this post


Link to post
Share on other sites
Due to a combination of tides and the Earth's rotation, the Moon currently is moving away from the Earth at the rate of about 4 centimetres per year, but this rate is gradually slowing down.

From what i read, we're able to determine the distance by bouncing laser beams from a mirror (mirrors?) left on the lunar surface by one of the Apollo missions. Something else i read was that as the Moon recedes, we won't have any more total eclipses of the Sun, they'll all be annular. No idea how long that'll take to happen, though.

If anyone would like a good read, try 'The Once and Future Moon' by Paul Spudis. Very informative, and easy to understand.

Share this post


Link to post
Share on other sites
From what i read, we're able to determine the distance by bouncing laser beams from a mirror (mirrors?) left on the lunar surface by one of the Apollo missions.

Another reason that the moon landings were not a hoax. For an image, see

File:Lunar Laser McDonald Observatory.jpg - Wikimedia Commons.

The mirrors left were corner-cube reflectors like those in bicycle reflectors, so that the reflected beam goes back along the same path as the incident beam. This is how car drivers see the bicycle reflectors: light travels from headlights to reflector and back to the driver's eyes, no matter the angle between bike and car.

Something else i read was that as the Moon recedes, we won't have any more total eclipses of the Sun, they'll all be annular. No idea how long that'll take to happen, though.

I hadn't thought about that. It has to happen eventually.

Edited by George Jones

Share this post


Link to post
Share on other sites
From what i read, we're able to determine the distance by bouncing laser beams from a mirror (mirrors?) left on the lunar surface by one of the Apollo missions. Something else i read was that as the Moon recedes, we won't have any more total eclipses of the Sun, they'll all be annular. No idea how long that'll take to happen, though.

If anyone would like a good read, try 'The Once and Future Moon' by Paul Spudis. Very informative, and easy to understand.

I had never thought of that. As the Moon moves further away there will be no more total solar eclipses (and fewer lunar eclipses also). Thats a good few million yrs away though.

As for measuring the distance from Earth to Moon.............yep that is done with lasers and mirror(s) left on the Moon during an Apollo mission. If there was no man made mirror there we could simply not take those measurements.............................this single fact alone proves without doubt that man went to the moon.

Edited by LukeSkywatcher

Share this post


Link to post
Share on other sites

Back on the location of lunar volcanic activity, would we not expect it to be more equatorial than polar anyway? The tidal forces affecting planets are strongest on their equators because there you have the greatest distances between that side near the gravitating companion and that which is further away. Therefore the flexing of the crust is greatest there, weaking it and leaving it prone to fissure. (I don't know If this is so, it just struck me as reasonable.)

Another nice observation on the Moon is to note that small craters overlap large ones but not the reverse, tracing the reducing size of the impactors. Quite reassuring when you think about it...

Still resent the darned thing making my booking schedule such a nightmare though!!

Olly

Edited by ollypenrice

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.