You don't need a telescope

, thanks for adding to that . However your still only seeing a first or last Quarter moon .

I wonder if we will ever see a situation where the moon revolves different from what it does now, and we get to see the other side of the moon?????


P.

No , not unless something drastic happens in space .

Pagman wrote in post #17972693
I wonder if we will ever see a situation where the moon revolves different from what it does now, and we get to see the other side of the moon?????


P.

Nope, but the earth IS slowly becoming tidal locked to the moon much in the same way the moon is tidal locked to the earth. Of course it won't fully happen for billions of years and by then the sun will have probably gone all nutso and destroyed us.


As much as I hate to say it, imaging the moon bores me (/ducks). I think I've only ever really put effort into doing it once (besides eclipse events), this is the only real picture I tried to make quality:

Tonights moon hand held X-S1 bridge camera, just a quick man focus job trying out the focus assist, next time i will try it out using the tripod i now have.

P.

I have never been able to get a crisp image of a daytime moon with AF or MF . So good luck however you do it !

Here's a daytime moon I shot this evening. I let the lens focus it for me, then switched the Auto-Focus off. The VC was turned on, too. This is cropped quite a bit, and reduced to post. I did sharpen it one step to compensate for sharpness lost when I reduced it, and adjusted the gamma and contrast to darken it and bring out more detail. I was pleasantly surprised at how well it turned out. There's a slight outline around the edge, and I don't know what caused that - maybe the adjustments or sharpening. (???)

This was taken April 15, 2016, at 7:23 PM. I shot it with a Nikon D5200 camera, Tamron 150-600 lens at 600mm. Exposure was 1/60 second, f:11.0, ISO 100. It was on a standard tripod.

Pagman wrote in post #17972693
I wonder if we will ever see a situation where the moon revolves different from what it does now, and we get to see the other side of the moon?????


P.

Never... the moon is "tidally locked" and it's slightly non-spherical (due to tidal forces of the Earth). The Moon is also very fractionally slowing the spin of the Earth (it's working on trying to make the Earth tidally locked to the moon). The energy from Earth's spin is very slow transferred to the moon and lifts into a fractionally higher orbit each year. This will continue until the Earth is eventually tidally locked to the moon (allegedly a person living when this happens would only see the moon if they live on the moon-facing side of the planet and inhabitants of the other side of the planet would never see the moon). I say "allegedly" because this process is extremely slow... so slow that the Sun will likely swell so large in it's old age that it engulfs both the Earth and the Moon before the process of tidal locking can ever be completed.

Were it not for that... the moon would eventually make it's way up to an orbit much farther than it's current orbit, the spin of the Earth would slow until it became tidally locked to the Moon... and then the moon would gradually have it's orbit decay until it hits the Roche limit and gets shredded into tiny objects which would likely create a ring system around the Earth. The ring system itself would eventually decay and crash to the Earth. But that is unlikely to happen before the Sun burns out.

TCampbell wrote in post #17974174
Never... the moon is "tidally locked" and it's slightly non-spherical (due to tidal forces of the Earth). The Moon is also very fractionally slowing the spin of the Earth (it's working on trying to make the Earth tidally locked to the moon). The energy from Earth's spin is very slow transferred to the moon and lifts into a fractionally higher orbit each year. This will continue until the Earth is eventually tidally locked to the moon (allegedly a person living when this happens would only see the moon if they live on the moon-facing side of the planet and inhabitants of the other side of the planet would never see the moon). I say "allegedly" because this process is extremely slow... so slow that the Sun will likely swell so large in it's old age that it engulfs both the Earth and the Moon before the process of tidal locking can ever be completed.

Were it not for that... the moon would eventually make it's way up to an orbit much farther than it's current orbit, the spin of the Earth would slow until it became tidally locked to the Moon... and then the moon would gradually have it's orbit decay until it hits the Roche limit and gets shredded into tiny objects which would likely create a ring system around the Earth. The ring system itself would eventually decay and crash to the Earth. But that is unlikely to happen before the Sun burns out.

Thats very ery interesting as i often as most folk do - look up at the moon and sometimes its difficult and makes my head hurt trying to work out all the ins and outs of its relationship with Earth, is most known - is its effect on the tides, but most folk would not be able to work out the reason for this appart for what i thought - magnetics like to different magnits attracting each other.
The other fantasy thing that goes through my mind is - what would happen if a mutch mutch larger planet was in the same orbit or distance from us but say it was 3-4 times our size, what effect would that have on us?

P.

Pagman wrote in post #17974180
Thats very ery interesting as i often as most folk do - look up at the moon and sometimes its difficult and makes my head hurt trying to work out all the ins and outs of its relationship with Earth, is most known - is its effect on the tides, but most folk would not be able to work out the reason for this appart for what i thought - magnetics like to different magnits attracting each other.
The other fantasy thing that goes through my mind is - what would happen if a mutch mutch larger planet was in the same orbit or distance from us but say it was 3-4 times our size, what effect would that have on us?

P.

We'd have a faster orbit around each other with our Barycenter (center of orbit) closer to the more massive object and our tides would be huge. Also, we'd likely become tidally locked to the more massive object much more quickly.

TCampbell wrote in post #17974217
We'd have a faster orbit around each other with our Barycenter (center of orbit) closer to the more massive object and our tides would be huge. Also, we'd likely become tidally locked to the more massive object much more quickly.

So - Game over bye bye Earth...


P.

milkyway shot with a nikon 28mm f/2.8

TCampbell wrote in post #17974174
Never... the moon is "tidally locked" and it's slightly non-spherical (due to tidal forces of the Earth). The Moon is also very fractionally slowing the spin of the Earth (it's working on trying to make the Earth tidally locked to the moon). The energy from Earth's spin is very slow transferred to the moon and lifts into a fractionally higher orbit each year. This will continue until the Earth is eventually tidally locked to the moon (allegedly a person living when this happens would only see the moon if they live on the moon-facing side of the planet and inhabitants of the other side of the planet would never see the moon). I say "allegedly" because this process is extremely slow... so slow that the Sun will likely swell so large in it's old age that it engulfs both the Earth and the Moon before the process of tidal locking can ever be completed.

Were it not for that... the moon would eventually make it's way up to an orbit much farther than it's current orbit, the spin of the Earth would slow until it became tidally locked to the Moon... and then the moon would gradually have it's orbit decay until it hits the Roche limit and gets shredded into tiny objects which would likely create a ring system around the Earth. The ring system itself would eventually decay and crash to the Earth. But that is unlikely to happen before the Sun burns out.

You ever watch the show How the Universe Works on the Science Channel? There is a whole episode about just this. It's a great show, with folks including Lawrence Krauss, Phil Plaitt, Michiu Kaku, Michelle Thaller, Hakeem Oluseyi, Alan Guth, and really countless PhD's in Planetary Physics, Astronomy, Cosmology, etc. It's a great show, we filled our DVR with it and watch it pretty much every night around bedtime. I highly recommend it, we gave my pops the first 3 seasons on DVD for Christmas this year.

Pagman wrote in post #17974180
its relationship with Earth, is most known - is its effect on the tides, but most folk would not be able to work out the reason for this appart for what i thought - magnetics like to different magnits attracting each other.
The other fantasy thing that goes through my mind is - what would happen if a mutch mutch larger planet was in the same orbit or distance from us but say it was 3-4 times our size, what effect would that have on us?

P.

Except, it's gravity, not magnetism, which is a far weaker force and only attracts.

The thinking is that there once was a much larger planet nearer to Earth, it was Jupiter, and it cleared out a lot of material before tacking out to its current position in the solar system. That's one reason Earth is so small. And there was likely another larger planet in the same area as Earth as well. It was called Theia. Theia collided with Earth, shattering in the process of blowing off a lot of Earth's material. This formed a ring system around Earth with coalesced into the Moon we see today. This is the Great Impact Theory of the formation of the moon which is the currently accepted theory.

https://en.wikipedia.o​rg/wiki/Giant_impact_h​ypothesis

For the Jupiter part, see the Grand Tack Hypothesis.

https://en.wikipedia.o​rg/wiki/Grand_tack_hyp​othesis

There is also this very recent study about Jupiter forming much closer to the Sun:
https://www.sciencenew​s.org …-inner-solar-system-clean

les_au wrote in post #17974335
milkyway shot with a nikon 28mm f/2.8

Hosted photo: posted by les_au in
./showthread.php?p=179​74335&i=i148775403
forum: Astronomy & Celestial

That's a nice image -- just a little long on the exposure time. Notice that the stars around the edges of the frame are all swirling toward a point roughly located in the right lower third of the frame (that's the location of the south celestial pole.) The farther the star is from that pole, the faster it seem to move (and hence the longer the star-trail in the image.)

Stars appear to move at about 15 arc-seconds per second at the equator (a star with declination 0º appears to travel directly above Earth's equator). But a star located precisely at the celestial pole will not appear to move at all -- it will remain stationary. The apparent angular rate of movement is found by multiplying the speed of Earth's rotation (15 arc seconds per second) by the cosine of the star's declination. You used a 28mm lens on an APS-C camera. That gives you a 54º range when measured diagonal (corner to corner). Had the south celestial pole been centered then that would mean the stars are 27º away from center at the corners but in your image let's eyeball it at a 2/3 : 1/3 split. That puts the upper left corner at about 36º away from the celestial pole and the lower right corner is roughly 18º from the pole.

That makes the stars in the upper left located at roughly declination 90-36 = 54º. The cosine of 54º is about .59 (rounded). That means your will appear to be moving at about .59 x 15 arc-secs/sec or only about 8.85 arc-seconds per sec.

That means you can "cheat" on the exposure time... but only by the margin equal to the apparent change in speed.

For your camera and lens combination, normally you'd want to keep the exposure time at 400 ÷ 28 = 14 seconds. If we divide that by .59 we get about 24 seconds (so you gain about 10 seconds because you are shooting a region closer to the pole.)

Your image just says "bulb" so we don't know how long you used for exposure, but I think if you re-shoot and keep the exposure to 24 seconds you *should* avoid any star trails in the image.