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From a million miles away, NASA camera shows moon crossing face of Earth

nasa.gov

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Re: From a million miles away, NASA camera shows moon crossing face of Earth

#131

Post by mrschwabe »

Tobold wrote: post #43

Someone tweeted this yesterday and some of the replies were really disheartening. Several people were calling it fake, with varying explanations of either "The earth is flat" or "Everybody knows the whole space program is fake". I knew people out there actually believe this, but damn...

I don't find these kind of replies disheartening. I think scepticism of NASA is a good thing. Because some of that scepticism might translate into new research, new developments, new experiments, and maybe even new entrepreneurial efforts in space.

Re: From a million miles away, NASA camera shows moon crossing face of Earth

#132

Post by scott_s »

vinhboy wrote: post #119
exodust wrote: post #100

Here's what one million miles looks like side on...(whipped up in Photoshop) Best viewed at 100%. The image is more or less to scale. Scroll a million miles to the right to find moon and camera. (don't worry it's only a 300K jpeg) http://ozimg.s3.amazonaws.com/earth-moon-from-million-miles....

Dang.. it never occurred to me how big the moon is. Looking at this picture, it's hard for me to comprehend why the moon would orbit the earth and not fall into the sun.

TunaFish and Retric gave great explanations, but I want to add a quick conceptual point: the moon (and the Earth) is falling into the sun. Constantly. It's just that the moon (and the Earth, and the other planets) have so much velocity tangential to the direction of the sun that instead of falling into the sun, they fall around the sun. That's what an orbit is.

Re: From a million miles away, NASA camera shows moon crossing face of Earth

#133

Post by scott_s »

mrschwabe wrote: post #131
Tobold wrote: post #43

Someone tweeted this yesterday and some of the replies were really disheartening. Several people were calling it fake, with varying explanations of either "The earth is flat" or "Everybody knows the whole space program is fake". I knew people out there actually believe this, but damn...

I don't find these kind of replies disheartening. I think scepticism of NASA is a good thing. Because some of that scepticism might translate into new research, new developments, new experiments, and maybe even new entrepreneurial efforts in space.

Tobold is not describing rational skepticism of NASA's ability to fulfill its mission. Tobold is describing conspiracy theories and people who have fundamental misunderstandings of science.

Re: From a million miles away, NASA camera shows moon crossing face of Earth

#134

Post by pzaich »

UserRights wrote: post #74

It is really cool how the NASA gives us a better understanding of the universe and our place in it by publishing all these nice pictures. However, I would like to have one easy accessible source for all the nice pictures that is daily updated and could be synchronized to a local school server e.g. with rsync. Is there one "ḧere-are-all-the-pics"-ftp server anywhere? It is quite time consuming to browse the hundreds o…

I think the same could be said for all public domain images published by the government. There must be a tremendous wealth of high quality photos that are hidden away on various agency websites. I've been thinking about creating an aggregation service for this similar to unsplash.com.

Re: From a million miles away, NASA camera shows moon crossing face of Earth

#135

Post by meatysnapper »

visakanv wrote: post #126
nitrogen wrote: post #121

Earlier quoted context omitted.

Those pictures have already been paid for by taxes. We should not have to pay for them again.

you wouldn't be paying for the images, you'd be paying to have somebody do the grunt work of organizing them, presenting them, etc

I want to emphasize that organizing these images would be a non-trivial amount of work. More worthwhile than bombing a bunch of sand people somewhere, certainly, but still non-trivial.

Re: From a million miles away, NASA camera shows moon crossing face of Earth

#136

Post by bmm6o »

mattlutze wrote: post #97
2Pacalypse- wrote: post #78

Earlier quoted context omitted.

Not quite what you requested, but NASA's Astronomy Picture of the Day[1] is very cool. It has an archive dating back to the 1995! [1] - http://apod.nasa.gov/apod/

Completely unnecessary side note: It's run by one of my old professors[1]! The whole physics department at Michigan Tech is a cool little diamond in the middle of the Upper Peninsula rough. 1: http://www.phy.mtu.edu/faculty/Nemiroff.html

(Totally off-topic, but that's not a very apt usage of "diamond in the rough": https://en.wiktionary.org/wiki/diamond_in_the_rough )

Re: From a million miles away, NASA camera shows moon crossing face of Earth

#137

Post by rootbear »

Tuna-Fish wrote: post #125
vinhboy wrote: post #119

Earlier quoted context omitted.

Dang.. it never occurred to me how big the moon is. Looking at this picture, it's hard for me to comprehend why the moon would orbit the earth and not fall into the sun.

The gravitational influence of the Sun on the Moon is greater than the gravitational influence of the Earth. In a very real way, the moon is orbiting the Sun. However, the orbit it flies around the Earth only very slightly modifies it's orbit around the Sun. The lunar orbital speed around the earth is ~1km/s, while the orbital speed around the sun is ~30km/s. That is, it never loops backwards on it's path around the…

Nice illustration in wikipedia. I first learned about this feature of the moon's orbit from one of Isaac Asimov's science essays. In many ways, the Earth and Moon are like a double planet, though not so much as Pluto and Charon.

Re: From a million miles away, NASA camera shows moon crossing face of Earth

#138

Post by rootbear »

Cyykratahk wrote: post #44
gonvaled wrote: post #26

Moon is tidally locked to Earth, which is interesting. How long will this last? How long has this been going on? Does this happen to all satellites in all planets? Another question: is the Moon orbiting plane aligned with the Earth rotation axis? Why or why not?

Interestingly, the moon's tidal lock is not perfect, resulting in a wobble that can be seen in time lapses: http://svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=4236

I used to work in the SVS and Ernie, who made those images, got to be a real expert on the complexities of the moon's orbit. He did some really great work. Check out the SVS website for more.

Re: From a million miles away, NASA camera shows moon crossing face of Earth

#139

Post by murbard2 »

vinhboy wrote: post #119
exodust wrote: post #100

Here's what one million miles looks like side on...(whipped up in Photoshop) Best viewed at 100%. The image is more or less to scale. Scroll a million miles to the right to find moon and camera. (don't worry it's only a 300K jpeg) http://ozimg.s3.amazonaws.com/earth-moon-from-million-miles....

Dang.. it never occurred to me how big the moon is. Looking at this picture, it's hard for me to comprehend why the moon would orbit the earth and not fall into the sun.

The moon is falling into the sun, just like the earth.

Re: From a million miles away, NASA camera shows moon crossing face of Earth

#140

Post by coldsmoke »

Sakes wrote: post #53
gurtwo wrote: post #32

Why don't we see the Moon's shadow projected over the Earth in the pic? I guess it has to do with the relative distances of the 2 bodies to the Sun and the Moon's penumbra or something. Can someone make a digital image simulation of this to verify?

When the moon casts a shadow on the earth we (on the surface) experience it as a solar eclipse. For these images, the moon is not directly between the sun and the earth, so it cannot block sunlight from hitting the earth. So, no shadow.

But the satellite is at the L1 Lagrange point which is between the earth and the sun. So if you see the moon pass in front of the earth from L1 shouldn't the moon then also be directly between the earth and the sun? And as someone in another post noted: you can see the suns reflection in the ocean. And the moon passes directly over this spot.
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