It is surprising how much brighter Earth is than the moon
August 5, 2015 10:54 AM Subscribe
From a Million Miles Away, NASA Camera Shows Moon Crossing Face of Earth.
A NASA camera aboard the Deep Space Climate Observatory (DSCOVR) satellite captured a unique view of the moon as it moved in front of the sunlit side of Earth last month. The series of test images shows the fully illuminated “dark side” of the moon that is never visible from Earth.
The images were captured by NASA’s Earth Polychromatic Imaging Camera (EPIC) [PDF], a four megapixel CCD camera and telescope on the DSCOVR satellite orbiting 1 million miles from Earth. From its position between the sun and Earth, DSCOVR conducts its primary mission of real-time solar wind monitoring for the National Oceanic and Atmospheric Administration (NOAA).
This has made my day.
posted by vibrotronica at 11:01 AM on August 5, 2015 [2 favorites]
posted by vibrotronica at 11:01 AM on August 5, 2015 [2 favorites]
More like an EPIC photobomb.
posted by Zack_Replica at 11:02 AM on August 5, 2015 [21 favorites]
posted by Zack_Replica at 11:02 AM on August 5, 2015 [21 favorites]
We live in a time of wonders. Throughout much of human history, people supposed the world was flat, and scant decades after tha Blue Marble and the Pale Blue Dot, we now have the Earth and Moon in a family portrait.
posted by Gelatin at 11:05 AM on August 5, 2015 [2 favorites]
posted by Gelatin at 11:05 AM on August 5, 2015 [2 favorites]
Pictures of planets, moons and spaceships are always made better when their are other planets, moons, or spaceships in the same picture. The ISS with the Shuttle attached, a rover parachuting down to Mars, planetary conjunctions, whatever.
Maybe it's because space is so damn big and there is so much space between one thing and another that when you can manage to get two things in the same shot it's like finally getting that picture with your two uncles who haven't spoken to each other since that one Christmas that the family doesn't like to talk about.
posted by bondcliff at 11:06 AM on August 5, 2015 [13 favorites]
Maybe it's because space is so damn big and there is so much space between one thing and another that when you can manage to get two things in the same shot it's like finally getting that picture with your two uncles who haven't spoken to each other since that one Christmas that the family doesn't like to talk about.
posted by bondcliff at 11:06 AM on August 5, 2015 [13 favorites]
Okay, that's just cool, and a really good demonstration of how much less light the moon reflects, compared to the Earth.* The full moon seems bright because it's in a really dark sky, but the moon really doesn't reflect much light at all, compared to the Earth.
Clouds are really good at reflecting visible light.
* The fancy science word here is "Albedo", but we'll gloss over that.
posted by eriko at 11:06 AM on August 5, 2015 [7 favorites]
Clouds are really good at reflecting visible light.
* The fancy science word here is "Albedo", but we'll gloss over that.
posted by eriko at 11:06 AM on August 5, 2015 [7 favorites]
"There is no dark side of the moon, really. Matter of fact, it's all dark."
posted by SansPoint at 11:06 AM on August 5, 2015 [9 favorites]
posted by SansPoint at 11:06 AM on August 5, 2015 [9 favorites]
Matter of fact, it's all dark
And turtles.
posted by roomthreeseventeen at 11:07 AM on August 5, 2015 [3 favorites]
And turtles.
posted by roomthreeseventeen at 11:07 AM on August 5, 2015 [3 favorites]
This shit is bananas.
posted by mandolin conspiracy at 11:08 AM on August 5, 2015 [5 favorites]
posted by mandolin conspiracy at 11:08 AM on August 5, 2015 [5 favorites]
Oh, be carful with scale here. DSCOVR is in a sun-synchronous orbit, which is outside of the Moon's orbit, so that puts the Moon *much* closer to the camera than the Earth. Thus, we have quite a bit of forced perspective here. This is a more accurate comparison of the two when it comes to size.
posted by eriko at 11:10 AM on August 5, 2015 [16 favorites]
posted by eriko at 11:10 AM on August 5, 2015 [16 favorites]
No uncloaked alien base on the other side. I am disappoint.
I ain't sayin'; I'm just sayin'.
posted by gauche at 11:11 AM on August 5, 2015 [5 favorites]
I ain't sayin'; I'm just sayin'.
posted by gauche at 11:11 AM on August 5, 2015 [5 favorites]
No alien base on the other side. I am disappoint.
What are you talking about? It's right there in plain sight.
Just zoom in and look at the pixels. Look just to the right of the face of Jesus!
God damn it, people, it's right there!
posted by Naberius at 11:15 AM on August 5, 2015 [1 favorite]
What are you talking about? It's right there in plain sight.
Just zoom in and look at the pixels. Look just to the right of the face of Jesus!
God damn it, people, it's right there!
posted by Naberius at 11:15 AM on August 5, 2015 [1 favorite]
DSCOVR is in a sun-synchronous orbit, which is outside of the Moon's orbit, so that puts the Moon *much* closer to the camera than the Earth. Thus, we have quite a bit of forced perspective here.
Moon: I'm crushing your head! I'm crushing your head!
posted by Atom Eyes at 11:15 AM on August 5, 2015 [10 favorites]
Moon: I'm crushing your head! I'm crushing your head!
posted by Atom Eyes at 11:15 AM on August 5, 2015 [10 favorites]
Earth's albedo is 0.39 (an albedo of 1.0 is total light reflection) [I know this because Vangelis named an album Albedo 0.39 decades ago.]
Moon's albedo is 0.12.
Less than 1/3 of the same light reflection which is already only just more than 1/3 of total light reflection.
posted by hippybear at 11:18 AM on August 5, 2015 [4 favorites]
Moon's albedo is 0.12.
Less than 1/3 of the same light reflection which is already only just more than 1/3 of total light reflection.
posted by hippybear at 11:18 AM on August 5, 2015 [4 favorites]
When I first saw this this morning it made me realize how significant to the development of life on Earth and human civilization the moon's low albedo really is. Given how much reflected illumination you get on a night with a full moon as it is, with a 12% albedo -- which basically means it's like a pretty dark gray, similar to the volcanic rock you might be familiar with -- imagine if it had an ice surface. You'd get near-daylight conditions through a large proportion of nights.
posted by George_Spiggott at 11:21 AM on August 5, 2015 [1 favorite]
posted by George_Spiggott at 11:21 AM on August 5, 2015 [1 favorite]
The Moon is out of focus. DSCOVR needs to stop down and get a little more depth of field. It would probably help with the chromatic aberration, too.
posted by 1970s Antihero at 11:21 AM on August 5, 2015 [3 favorites]
posted by 1970s Antihero at 11:21 AM on August 5, 2015 [3 favorites]
Who knew that the moon was so vain... clearly it chose to permanently hide its less interesting side and only show off the flashy one.
posted by Hairy Lobster at 11:21 AM on August 5, 2015 [1 favorite]
posted by Hairy Lobster at 11:21 AM on August 5, 2015 [1 favorite]
It is surprising how much brighter Earth is than the moon
Even more surprising is how heavily cratered the far side of the moon is compared to how smooth the near side is. And in case you are wondering, it's not because of the earth blocking meteors. If you were standing on the moon you would see that the earth blocks only a tiny portion of the sky. More likely is some asymmetry in the formation of the moon's crust so that it is thinner on the near side and more prone to volcanism that erased impacts.
posted by JackFlash at 11:22 AM on August 5, 2015 [1 favorite]
Even more surprising is how heavily cratered the far side of the moon is compared to how smooth the near side is. And in case you are wondering, it's not because of the earth blocking meteors. If you were standing on the moon you would see that the earth blocks only a tiny portion of the sky. More likely is some asymmetry in the formation of the moon's crust so that it is thinner on the near side and more prone to volcanism that erased impacts.
posted by JackFlash at 11:22 AM on August 5, 2015 [1 favorite]
coincidence, or the result of Atlantean missile testing?
posted by theodolite at 11:23 AM on August 5, 2015 [2 favorites]
posted by theodolite at 11:23 AM on August 5, 2015 [2 favorites]
a four megapixel CCD camera
It's amazing and cool how low tech things can work just fine.
posted by Brandon Blatcher at 11:24 AM on August 5, 2015 [1 favorite]
It's amazing and cool how low tech things can work just fine.
posted by Brandon Blatcher at 11:24 AM on August 5, 2015 [1 favorite]
The moon is weird.
posted by swift at 11:27 AM on August 5, 2015 [1 favorite]
posted by swift at 11:27 AM on August 5, 2015 [1 favorite]
The Deep Space Climate Observatory, or DSCOVR
One of my favorite things about NASA is how all their acronyms are hilarious or clever or both. I love picturing the most highly educated scientists on the planet sitting around a room trying to come up with names for things that can be reduced to the cutest possible acronyms.
posted by something something at 11:29 AM on August 5, 2015
One of my favorite things about NASA is how all their acronyms are hilarious or clever or both. I love picturing the most highly educated scientists on the planet sitting around a room trying to come up with names for things that can be reduced to the cutest possible acronyms.
posted by something something at 11:29 AM on August 5, 2015
My albedo is pretty low these days... Thanks a lot, anti-depressants.
posted by symbioid at 11:31 AM on August 5, 2015 [3 favorites]
posted by symbioid at 11:31 AM on August 5, 2015 [3 favorites]
Why are you all calling it DSCOVR when in point of fact its one true name is GoreSat*?
------------------------
*Also acceptable is "Al Gore's Satellite."
posted by notyou at 11:32 AM on August 5, 2015 [3 favorites]
------------------------
*Also acceptable is "Al Gore's Satellite."
posted by notyou at 11:32 AM on August 5, 2015 [3 favorites]
Earth's albedo is 0.39 (an albedo of 1.0 is total light reflection) [I know this because Vangelis named an album Albedo 0.39 decades ago.]
SUCH a good album, bits and pieces of which were used in the music for Cosmos.
Title Track
Pulstar
Alpha
posted by Celsius1414 at 11:39 AM on August 5, 2015 [2 favorites]
SUCH a good album, bits and pieces of which were used in the music for Cosmos.
Title Track
Pulstar
Alpha
posted by Celsius1414 at 11:39 AM on August 5, 2015 [2 favorites]
This is a more accurate comparison of the two when it comes to size.
I never realized they were so close together, though.
Just kidding. This is really cool!
posted by TedW at 11:46 AM on August 5, 2015 [1 favorite]
I never realized they were so close together, though.
Just kidding. This is really cool!
posted by TedW at 11:46 AM on August 5, 2015 [1 favorite]
This is a nice shot Galileo took of the Earth and Moon together in 1992.
posted by aught at 11:48 AM on August 5, 2015 [6 favorites]
posted by aught at 11:48 AM on August 5, 2015 [6 favorites]
Moon looks like shit next to Earth.
posted by colie at 11:51 AM on August 5, 2015 [3 favorites]
posted by colie at 11:51 AM on August 5, 2015 [3 favorites]
Fuck the moon.
posted by Keith Talent at 11:51 AM on August 5, 2015 [5 favorites]
posted by Keith Talent at 11:51 AM on August 5, 2015 [5 favorites]
No alien base on the other side
Neither Pink Floyd
Nor Haywood Floyd
Nor Cha
posted by Ogre Lawless at 11:55 AM on August 5, 2015 [1 favorite]
Neither Pink Floyd
Nor Haywood Floyd
Nor Cha
posted by Ogre Lawless at 11:55 AM on August 5, 2015 [1 favorite]
So that sequence took about five hours to shoot and there are, what, fifteen frames there? So that's one shot every forty minutes or so. I wonder what the limiting factor is. It'd be nice to have more.
I'm presuming this is going to happen once a month, but given the Earth's weather will change so much that's not going to be a way to build up more.
posted by Devonian at 11:57 AM on August 5, 2015
I'm presuming this is going to happen once a month, but given the Earth's weather will change so much that's not going to be a way to build up more.
posted by Devonian at 11:57 AM on August 5, 2015
Fuck the moon.
Would you like to yell at the Moon with Buzz Aldrin?
posted by bondcliff at 11:58 AM on August 5, 2015 [1 favorite]
Would you like to yell at the Moon with Buzz Aldrin?
posted by bondcliff at 11:58 AM on August 5, 2015 [1 favorite]
The thing that always seems most surprising is how far away the moon is compared to the size of the earth. Like about 30 diameters.
posted by merlynkline at 12:00 PM on August 5, 2015
posted by merlynkline at 12:00 PM on August 5, 2015
I've just realized that these satellites taking photos looking back at Earth are just vastly upscaled versions of selfie sticks.
I'm not sure how I feel about it.
posted by benito.strauss at 12:00 PM on August 5, 2015 [12 favorites]
I'm not sure how I feel about it.
posted by benito.strauss at 12:00 PM on August 5, 2015 [12 favorites]
I was just sure that image was fake as hell. Too badass to be real.
posted by Zerowensboring at 12:01 PM on August 5, 2015
posted by Zerowensboring at 12:01 PM on August 5, 2015
I've just realized that these satellites taking photos looking back at Earth are just vastly upscaled versions of selfie sticks.
"The space Selfie Stick will be built ten years after everyone stops laughing." -- Arthur C. Clarke.
posted by bondcliff at 12:05 PM on August 5, 2015 [4 favorites]
"The space Selfie Stick will be built ten years after everyone stops laughing." -- Arthur C. Clarke.
posted by bondcliff at 12:05 PM on August 5, 2015 [4 favorites]
I've just realized that these satellites taking photos looking back at Earth are just vastly upscaled versions of selfie sticks.
Or really, really expensive drones.
posted by mandolin conspiracy at 12:06 PM on August 5, 2015 [1 favorite]
Or really, really expensive drones.
posted by mandolin conspiracy at 12:06 PM on August 5, 2015 [1 favorite]
So that's one shot every forty minutes or so. I wonder what the limiting factor is. It'd be nice to have more.
From here: "It images the irradiance from the sunlit face of Earth on a 2048x2048 pixel CCD (charge-coupled device) in 10 narrowband channels: 317, 325, 340, 388, 443, 552, 680, 688, 764 and 779 nm. The wavelength spans ultraviolet and near infrared, and the exposure time for each channel is about 40 ms.
To increase the downlink cadence of retrieved 10-channel image sets, the resolution will be averaged on board to 1024x1024 pixels resulting in spatial sampling at 17 km from pixel to pixel with a resolvable size of 25 km. The time cadence will be no faster than 10 spectral band images every hour."
The camera itself is pretty fast, in the milliseconds, but it needs 10 images to provide a full color spectrum. The real limiting factor seems to be the downlink. The satellite is really far away, at the Lagrange L1 point, about 4 times the distance to the moon and 40 times the distance to your geosynchronous Dish TV satellite.
posted by JackFlash at 12:16 PM on August 5, 2015 [4 favorites]
From here: "It images the irradiance from the sunlit face of Earth on a 2048x2048 pixel CCD (charge-coupled device) in 10 narrowband channels: 317, 325, 340, 388, 443, 552, 680, 688, 764 and 779 nm. The wavelength spans ultraviolet and near infrared, and the exposure time for each channel is about 40 ms.
To increase the downlink cadence of retrieved 10-channel image sets, the resolution will be averaged on board to 1024x1024 pixels resulting in spatial sampling at 17 km from pixel to pixel with a resolvable size of 25 km. The time cadence will be no faster than 10 spectral band images every hour."
The camera itself is pretty fast, in the milliseconds, but it needs 10 images to provide a full color spectrum. The real limiting factor seems to be the downlink. The satellite is really far away, at the Lagrange L1 point, about 4 times the distance to the moon and 40 times the distance to your geosynchronous Dish TV satellite.
posted by JackFlash at 12:16 PM on August 5, 2015 [4 favorites]
This sort of made me want to grab my chair or even the floor and hang on tight. Something like vertigo but on a larger existential scale, and in kind of a good way.
posted by Orange Dinosaur Slide at 12:18 PM on August 5, 2015 [3 favorites]
posted by Orange Dinosaur Slide at 12:18 PM on August 5, 2015 [3 favorites]
Wikipedia tells me lunar rock is rich in both Magnesium and Oxygen. The solution is obvious: We need to coat the moon in magnesium oxide, raising its albedo from a wimpy 0.12 to an impressive 0.96.
posted by fings at 12:31 PM on August 5, 2015
posted by fings at 12:31 PM on August 5, 2015
I was wondering about the downlink, and that's got more than just physics to worry about - if it's using the DSN, then that's expensive (*). The amount of storage on the satellite is also a factor; assuming that the Moon shot (!) was in just three spectral bands, then that explains how you get three full-colour shots an hour with the 10 f/h cadence. But if you can store a lot more frames, then you can presumably interleave them with operational data return at your leisure and get a much higher final frame count down over time.
Or you might just not bother.
(* There's an increasing number of cubesats that supplement their typically single-site ground stations, a severe limitation for LEO, with help from radio hams around the world, who receive, decode and send telemetry back to base over the Internet.)
posted by Devonian at 12:39 PM on August 5, 2015 [1 favorite]
Or you might just not bother.
(* There's an increasing number of cubesats that supplement their typically single-site ground stations, a severe limitation for LEO, with help from radio hams around the world, who receive, decode and send telemetry back to base over the Internet.)
posted by Devonian at 12:39 PM on August 5, 2015 [1 favorite]
Oh neat, this was taken on my birthday and I'm actually in the shot! (Toward the upper right, you might have to squint.)
DSCOVR is awesome and I feel like the most amazing thing about it is the thing that gets glossed over in most media coverage; yes, it's orbiting a million miles from Earth and that's cool in itself, but what I find even cooler is that it doesn't orbit the Earth at all. It is an artificial satellite orbiting the Sun at the L1 point where the pulls from the Earth and Sun balance out.
posted by contraption at 1:17 PM on August 5, 2015 [3 favorites]
DSCOVR is awesome and I feel like the most amazing thing about it is the thing that gets glossed over in most media coverage; yes, it's orbiting a million miles from Earth and that's cool in itself, but what I find even cooler is that it doesn't orbit the Earth at all. It is an artificial satellite orbiting the Sun at the L1 point where the pulls from the Earth and Sun balance out.
posted by contraption at 1:17 PM on August 5, 2015 [3 favorites]
ocschwar: No alien base on the other side. I am disappoint.
You can't see it? It's plain as day, right next to that big sign saying "FNORD"!
posted by brundlefly at 1:27 PM on August 5, 2015 [2 favorites]
You can't see it? It's plain as day, right next to that big sign saying "FNORD"!
posted by brundlefly at 1:27 PM on August 5, 2015 [2 favorites]
DSCOVR is in a sun-synchronous orbit, which is outside of the Moon's orbit, so that puts the Moon *much* closer to the camera than the Earth. Thus, we have quite a bit of forced perspective here.
What would really drive that home in a cool way is if that gif continued until the earth occulted a tinier moon. That should happen in like half a month right? If you could find a graceful way to deal with the extra 15 days of time you could make a really cool gif.
posted by cirrostratus at 1:51 PM on August 5, 2015
What would really drive that home in a cool way is if that gif continued until the earth occulted a tinier moon. That should happen in like half a month right? If you could find a graceful way to deal with the extra 15 days of time you could make a really cool gif.
posted by cirrostratus at 1:51 PM on August 5, 2015
I'm on an iPad, so I can only wonder...would the object rotation, along with the displacement of the moon, allow two frames to be juxtaposed to create a stereoscopic effect?
posted by bonobothegreat at 2:06 PM on August 5, 2015
posted by bonobothegreat at 2:06 PM on August 5, 2015
Look! It's Sam Rockwell!
I've always been partial to this image, showing Earth, Luna, and the distance between them to scale. Makes a nice desktop background, and gives some idea of just how alone the Apollo astronauts were.
By way of comparison the entire Pluto / Charon system, wobble and all, would fit nicely inside the orbit of our geostationary satellites.
I guess the new word of the month is albedo.
Last month's word was barycenter.
posted by Herodios at 2:07 PM on August 5, 2015 [9 favorites]
I've always been partial to this image, showing Earth, Luna, and the distance between them to scale. Makes a nice desktop background, and gives some idea of just how alone the Apollo astronauts were.
By way of comparison the entire Pluto / Charon system, wobble and all, would fit nicely inside the orbit of our geostationary satellites.
I guess the new word of the month is albedo.
Last month's word was barycenter.
posted by Herodios at 2:07 PM on August 5, 2015 [9 favorites]
Even more surprising is how heavily cratered the far side of the moon is compared to how smooth the near side is.
I guess you didn't hear about the Great Rustoleum Escape-Velocity Primer Eruption Disaster. Imagine a giant geyser of self-leveling gray spraypaint a quarter of a million miles high. It was in all the papers.
posted by George_Spiggott at 2:33 PM on August 5, 2015 [1 favorite]
I guess you didn't hear about the Great Rustoleum Escape-Velocity Primer Eruption Disaster. Imagine a giant geyser of self-leveling gray spraypaint a quarter of a million miles high. It was in all the papers.
posted by George_Spiggott at 2:33 PM on August 5, 2015 [1 favorite]
I've always been partial to this image, showing Earth, Luna, and the distance between them to scale. Makes a nice desktop background, and gives some idea of just how alone the Apollo astronauts were.
Or the one that shows you can fit all the other planets between the Earth and the Moon.
posted by Celsius1414 at 2:50 PM on August 5, 2015 [7 favorites]
Or the one that shows you can fit all the other planets between the Earth and the Moon.
posted by Celsius1414 at 2:50 PM on August 5, 2015 [7 favorites]
We live in amazing times.
posted by theora55 at 3:01 PM on August 5, 2015 [2 favorites]
posted by theora55 at 3:01 PM on August 5, 2015 [2 favorites]
so that puts the Moon *much* closer to the camera than the Earth. Thus, we have quite a bit of forced perspective here.
Not really. DSCOVR is is at ~ 1 million miles, and the Moon is at 250,000 miles, so simple geometry says that the Moon appears about 25% larger in diameter than it "should."
it's not because of the earth blocking meteors. If you were standing on the moon you would see that the earth blocks only a tiny portion of the sky
Actually, the differences between Nearside and Farside are because of the Earth blocking impactors. The Moon was, it's generally agreed, formed by a collision between Earth and a Mars-sized body toward the end of what is called the "late heavy bombardment." This was an epoch when many large bodies had coalesced from the gas and dust which formed the earlier solar disc, and the largest of those bodies were busily sweeping up the others to clear their orbital lanes.
When the moon was formed, it was a hell of a lot closer to the Earth, likely as close as one Earth diameter. The Moon tidally locked its rotation to Earth's fairly quickly, and then tidal interaction began trading the Earth's rotational momentum, which was much greater back then with the day being less than ten hours, for Lunar orbital momentum which caused it to start spiralling outward. (Bonus factoid: The Earth's rotational momentum making our day so different from Venus' is thought to have come from that collision too.)
The impact could have tossed the Moon into a retrograde orbit just as easily, but then those same tidal forces would have sucked it back in instead of spiralling it out. The spiralling out process continues to this day and can be measured with laser rangefinders.
So in those early days the Moon cooled but the late heavy bombardment went on, and Lunar farside was much more heavily affected because nearside was in fact shielded by the very close and relatively large Earth. In fact the final stages of the late heavy bombardment added several hundred feet to the thickness of the Lunar farside regolith, a fact which was quite mysterious until this impact scenario was worked out.
There were some large impacts on nearside by stuff that snuck by the Earth, and it's thought the maria might have been created by those few large late impactors. But Earth absorbed most of that stuff and Earth's weather and geology eventually erased the consequences. On the Moon, though, geological time mostly stopped around 4 billion years ago.
And then the Moon drifted further away and the Earth's day got longer. Even relatively "recently" the day was noticeably shorter than it is now. Any intelligent dinosaurs for example would have had a much different calendar with several dozen extra days per year.
posted by Bringer Tom at 3:28 PM on August 5, 2015 [10 favorites]
Not really. DSCOVR is is at ~ 1 million miles, and the Moon is at 250,000 miles, so simple geometry says that the Moon appears about 25% larger in diameter than it "should."
it's not because of the earth blocking meteors. If you were standing on the moon you would see that the earth blocks only a tiny portion of the sky
Actually, the differences between Nearside and Farside are because of the Earth blocking impactors. The Moon was, it's generally agreed, formed by a collision between Earth and a Mars-sized body toward the end of what is called the "late heavy bombardment." This was an epoch when many large bodies had coalesced from the gas and dust which formed the earlier solar disc, and the largest of those bodies were busily sweeping up the others to clear their orbital lanes.
When the moon was formed, it was a hell of a lot closer to the Earth, likely as close as one Earth diameter. The Moon tidally locked its rotation to Earth's fairly quickly, and then tidal interaction began trading the Earth's rotational momentum, which was much greater back then with the day being less than ten hours, for Lunar orbital momentum which caused it to start spiralling outward. (Bonus factoid: The Earth's rotational momentum making our day so different from Venus' is thought to have come from that collision too.)
The impact could have tossed the Moon into a retrograde orbit just as easily, but then those same tidal forces would have sucked it back in instead of spiralling it out. The spiralling out process continues to this day and can be measured with laser rangefinders.
So in those early days the Moon cooled but the late heavy bombardment went on, and Lunar farside was much more heavily affected because nearside was in fact shielded by the very close and relatively large Earth. In fact the final stages of the late heavy bombardment added several hundred feet to the thickness of the Lunar farside regolith, a fact which was quite mysterious until this impact scenario was worked out.
There were some large impacts on nearside by stuff that snuck by the Earth, and it's thought the maria might have been created by those few large late impactors. But Earth absorbed most of that stuff and Earth's weather and geology eventually erased the consequences. On the Moon, though, geological time mostly stopped around 4 billion years ago.
And then the Moon drifted further away and the Earth's day got longer. Even relatively "recently" the day was noticeably shorter than it is now. Any intelligent dinosaurs for example would have had a much different calendar with several dozen extra days per year.
posted by Bringer Tom at 3:28 PM on August 5, 2015 [10 favorites]
"When I first saw this this morning it made me realize how significant to the development of life on Earth and human civilization the moon's low albedo really is."
Here's an interesting piece by Bernard Foing titled If We Had No Moon. I've seen arguments in the past that life on Earth required the existence of the Moon, but that's an overstatement, probably. It's still really, really important in a number of different respects.
"I've just realized that these satellites taking photos looking back at Earth are just vastly upscaled versions of selfie sticks. "
The real selfie stick will be the observation module at the top of the space elevator, should such a thing ever exist.
"I've always been partial to this image, showing Earth, Luna, and the distance between them to scale."
All three are to scale? That's not what my intuition would have told me; I'd have placed the Moon much farther out. But that's just me being dumb, given that I know the relative diameters and the apparent size of the Moon in the sky. I'm feeling innumerate at the moment.
posted by Ivan Fyodorovich at 3:50 PM on August 5, 2015 [1 favorite]
Here's an interesting piece by Bernard Foing titled If We Had No Moon. I've seen arguments in the past that life on Earth required the existence of the Moon, but that's an overstatement, probably. It's still really, really important in a number of different respects.
"I've just realized that these satellites taking photos looking back at Earth are just vastly upscaled versions of selfie sticks. "
The real selfie stick will be the observation module at the top of the space elevator, should such a thing ever exist.
"I've always been partial to this image, showing Earth, Luna, and the distance between them to scale."
All three are to scale? That's not what my intuition would have told me; I'd have placed the Moon much farther out. But that's just me being dumb, given that I know the relative diameters and the apparent size of the Moon in the sky. I'm feeling innumerate at the moment.
posted by Ivan Fyodorovich at 3:50 PM on August 5, 2015 [1 favorite]
Well, the first time I saw the moon pass over the Earth, the Earth had just eclipsed the sun... And we were about to zoom out past Jupiter. But maybe I've just been spoiled.
posted by borborygmi at 4:14 PM on August 5, 2015
posted by borborygmi at 4:14 PM on August 5, 2015
No alien base on the other side. I am disappoint.
Wait, really? So am I the only one seeing that chthonic pentagram inscribed across the surface of the dark side? NASA claims it's just crater rays, I guess.
posted by straight at 4:29 PM on August 5, 2015 [1 favorite]
Wait, really? So am I the only one seeing that chthonic pentagram inscribed across the surface of the dark side? NASA claims it's just crater rays, I guess.
posted by straight at 4:29 PM on August 5, 2015 [1 favorite]
Keith Talent: "Fuck the moon."
Look out moon,
America's gonna getcha,
gonna go kaboom...
was nice to admit ya.
Cuz ya don't mess around...
with God's America!"
posted by symbioid at 4:32 PM on August 5, 2015
Look out moon,
America's gonna getcha,
gonna go kaboom...
was nice to admit ya.
Cuz ya don't mess around...
with God's America!"
posted by symbioid at 4:32 PM on August 5, 2015
The spiralling out process continues to this day
What will eventually happen? Will the moon just wander off, or will some equilibrium point be reached?
posted by Greg_Ace at 4:57 PM on August 5, 2015
What will eventually happen? Will the moon just wander off, or will some equilibrium point be reached?
posted by Greg_Ace at 4:57 PM on August 5, 2015
What will eventually happen?
Eventually the Earth will be tidally locked to the Moon, with the Moon orbiting around 450,000 miles if I remember correctly. Asimov wrote an essay about it once. Before that happens though the Sun will become a red giant and both Earth and Luna will probably be consumed by it.
posted by Bringer Tom at 5:11 PM on August 5, 2015 [1 favorite]
Eventually the Earth will be tidally locked to the Moon, with the Moon orbiting around 450,000 miles if I remember correctly. Asimov wrote an essay about it once. Before that happens though the Sun will become a red giant and both Earth and Luna will probably be consumed by it.
posted by Bringer Tom at 5:11 PM on August 5, 2015 [1 favorite]
Actually, the differences between Nearside and Farside are because of the Earth blocking impactors.
Let's just say there is some dispute about that. That is not what the scientists at the NASA Lunar Science Institute believe.
posted by JackFlash at 5:39 PM on August 5, 2015 [3 favorites]
Let's just say there is some dispute about that. That is not what the scientists at the NASA Lunar Science Institute believe.
posted by JackFlash at 5:39 PM on August 5, 2015 [3 favorites]
Before that happens though the Sun will become a red giant and both Earth and Luna will probably be consumed by it.
Awwwww. Lunus Interruptus, eh?
(Solus Interruptus?)
posted by Greg_Ace at 6:01 PM on August 5, 2015
Awwwww. Lunus Interruptus, eh?
(Solus Interruptus?)
posted by Greg_Ace at 6:01 PM on August 5, 2015
That is not what the scientists at the NASA Lunar Science Institute believe.
That page ignores the recent science from the late 1990's about the Moon's formation and the deep history of its tidal migration.
posted by Bringer Tom at 6:20 PM on August 5, 2015
That page ignores the recent science from the late 1990's about the Moon's formation and the deep history of its tidal migration.
posted by Bringer Tom at 6:20 PM on August 5, 2015
The satellite is really far away, at the Lagrange L1 point, about 4 times the distance to the moon and 40 times the distance to your geosynchronous Dish TV satellite.
Which is nothing, really. They've got 600W of power from the panels and a high gain antenna. They're don't even need the Deep Space Network. Most of the instruments downlink in real time by using the Near Earth Network, which includes a bunch of ground stations and the TDRS constellation. The EPIC images don't come down in real time, but the only time they'll use the DNS is if the NEN is just oversubscribed or if something's gone wrong with the bird. SOHO, in the same place, needs DSN support, but it's a much older satellite with much less power, runs a lot more instrumentation, downlinks 200kbps constantly, and frankly, the fact that SOHO still works is a miracle that make the Mars Rovers look like amateurs. SOHO was built for a two year mission, it's now on year 19, and it's been funded through year 21 -- despite the fact that we almost broke it by screwing up a bunch of commands and pointing it away from the sun (and the antenna away from Earth.)
Killer bird. You want the winner satellite? SOHO. Damn thing has been spitting data out longer that Metafilter. Damn thing turns out to be the best discovery tool we've had for comets! Over half the comets humanity has discovered have been found via SOHO. Just a cool satellite, and DSCOVER gets to go hang out by it.
Triana, I mean DSCOVR transmits on S band (which tells you right away it's not a deep space bird, they run on X or Ka band) and runs about 140kbps. That tells you it is also an old design, current designs would be running 10mbps or better, and the champ, the Lunar Reconnaissance Orbiter, had well over 100mbps, and had its own ground stations. But it only had to go lunar distances, but it had to downlink a staggering about of data.
posted by eriko at 6:27 PM on August 5, 2015 [5 favorites]
Which is nothing, really. They've got 600W of power from the panels and a high gain antenna. They're don't even need the Deep Space Network. Most of the instruments downlink in real time by using the Near Earth Network, which includes a bunch of ground stations and the TDRS constellation. The EPIC images don't come down in real time, but the only time they'll use the DNS is if the NEN is just oversubscribed or if something's gone wrong with the bird. SOHO, in the same place, needs DSN support, but it's a much older satellite with much less power, runs a lot more instrumentation, downlinks 200kbps constantly, and frankly, the fact that SOHO still works is a miracle that make the Mars Rovers look like amateurs. SOHO was built for a two year mission, it's now on year 19, and it's been funded through year 21 -- despite the fact that we almost broke it by screwing up a bunch of commands and pointing it away from the sun (and the antenna away from Earth.)
Killer bird. You want the winner satellite? SOHO. Damn thing has been spitting data out longer that Metafilter. Damn thing turns out to be the best discovery tool we've had for comets! Over half the comets humanity has discovered have been found via SOHO. Just a cool satellite, and DSCOVER gets to go hang out by it.
Triana, I mean DSCOVR transmits on S band (which tells you right away it's not a deep space bird, they run on X or Ka band) and runs about 140kbps. That tells you it is also an old design, current designs would be running 10mbps or better, and the champ, the Lunar Reconnaissance Orbiter, had well over 100mbps, and had its own ground stations. But it only had to go lunar distances, but it had to downlink a staggering about of data.
posted by eriko at 6:27 PM on August 5, 2015 [5 favorites]
or if something's gone wrong with the bird.
I love listening to space guys talk about their pets. I hear it's fucking hell getting a veterinarian out there, and you know the thing about birds, no redundant organs, mostly a sick bird is a dead bird.
posted by Bringer Tom at 6:34 PM on August 5, 2015
I love listening to space guys talk about their pets. I hear it's fucking hell getting a veterinarian out there, and you know the thing about birds, no redundant organs, mostly a sick bird is a dead bird.
posted by Bringer Tom at 6:34 PM on August 5, 2015
I apologize as I am sure there are better/easier ways to do this, but thought I'd share anyway.
As a do-I-remember-my-geometry exercise, I found myself wondering if I could figure out how far away DSCOVR was using this picture (well, plus a couple other facts). So I downloaded the image, and measured the Earth and the Moon's sizes in pixels. The Earth is 1590 pixels in diameter, and the Moon's diameter is 582 pixels.
Next I looked up the ratio of the diameters of Moon:Earth (0.273), which meant that if Earth were at the same distance as the Moon, it should be 1590/0.273=2132 pixels, or 2132/1590=1.34 times bigger. Similar triangles means that Earth must be 1.34x farther from DSCOVR than the moon. Let's call the distance from DSCOVR to the Moon "D", so that makes the distance to Earth 1.34*D. So Earth-Moon distance is 0.34D.
Looking up the approximate Earth-Moon distance (384000km), and dividing by 0.34, tells us D is 384000/0.34=1129000km; adding back in the 384000km E-M gives us the approximate distance to DSCOVR from Earth. 1,513,000km.
Now to check the answer. (Drumroll as I google "distance to L1"): "about 1.5 million kilometers".
Booyah!
posted by fings at 6:40 PM on August 5, 2015 [6 favorites]
As a do-I-remember-my-geometry exercise, I found myself wondering if I could figure out how far away DSCOVR was using this picture (well, plus a couple other facts). So I downloaded the image, and measured the Earth and the Moon's sizes in pixels. The Earth is 1590 pixels in diameter, and the Moon's diameter is 582 pixels.
Next I looked up the ratio of the diameters of Moon:Earth (0.273), which meant that if Earth were at the same distance as the Moon, it should be 1590/0.273=2132 pixels, or 2132/1590=1.34 times bigger. Similar triangles means that Earth must be 1.34x farther from DSCOVR than the moon. Let's call the distance from DSCOVR to the Moon "D", so that makes the distance to Earth 1.34*D. So Earth-Moon distance is 0.34D.
Looking up the approximate Earth-Moon distance (384000km), and dividing by 0.34, tells us D is 384000/0.34=1129000km; adding back in the 384000km E-M gives us the approximate distance to DSCOVR from Earth. 1,513,000km.
Now to check the answer. (Drumroll as I google "distance to L1"): "about 1.5 million kilometers".
Booyah!
posted by fings at 6:40 PM on August 5, 2015 [6 favorites]
DSCOVR is is at ~ 1 million miles, and the Moon is at 250,000 miles, so simple geometry says that the Moon appears about 25% larger in diameter than it "should."
Just a nitpick, but that should say "the Moon would appear 25% smaller (.75) at the earth's distance and it appears 33% larger at its real distance (1/.75). That is, it appears 33% larger than it "should".
posted by JackFlash at 6:43 PM on August 5, 2015
Just a nitpick, but that should say "the Moon would appear 25% smaller (.75) at the earth's distance and it appears 33% larger at its real distance (1/.75). That is, it appears 33% larger than it "should".
posted by JackFlash at 6:43 PM on August 5, 2015
Well Jackflash it's a matter of semantics. 25% of its apparent diameter is extra, which is kind of how I see it since it's an observation, but yeah of its "supposed to be" diameter we're seeing 133%. Different ends of a telescope as it were.
posted by Bringer Tom at 6:50 PM on August 5, 2015
posted by Bringer Tom at 6:50 PM on August 5, 2015
So cool! I imagine this is the first time the whole far side has been captured in a single photo. The large darker area in the southern half must be the South Pole-Aitken Basin.
posted by gubo at 7:02 PM on August 5, 2015
posted by gubo at 7:02 PM on August 5, 2015
it's a matter of semantics.
It's not semantics. It's math. You could say the moon should be 25% smaller. Or you could say that the moon does appear 33% larger. But in no way is it correct to say the the moon appears 25% larger.
posted by JackFlash at 7:14 PM on August 5, 2015
It's not semantics. It's math. You could say the moon should be 25% smaller. Or you could say that the moon does appear 33% larger. But in no way is it correct to say the the moon appears 25% larger.
posted by JackFlash at 7:14 PM on August 5, 2015
OK, whatever.
posted by Bringer Tom at 7:26 PM on August 5, 2015
posted by Bringer Tom at 7:26 PM on August 5, 2015
Arthur C. Clarke published Transit of Earth (...Earth in front of the Sun, but still...) in 1971.
posted by AsYouKnow Bob at 7:37 PM on August 5, 2015 [1 favorite]
posted by AsYouKnow Bob at 7:37 PM on August 5, 2015 [1 favorite]
... mostly a sick bird is a dead bird.
'E's restin'!
I have to say, as someone who grew up in the sixties along with the space program, that I love space threads on MeFi. And I have come to realize that eriko is to satellites what Brockles is to cars.
posted by TedW at 2:10 PM on August 6, 2015 [1 favorite]
'E's restin'!
I have to say, as someone who grew up in the sixties along with the space program, that I love space threads on MeFi. And I have come to realize that eriko is to satellites what Brockles is to cars.
posted by TedW at 2:10 PM on August 6, 2015 [1 favorite]
Button moon
posted by fearfulsymmetry at 12:18 PM on August 5
I LOVED Button Moon when I was a kid!! Brings back memories!
posted by cynical pinnacle at 5:53 PM on August 6, 2015 [1 favorite]
posted by fearfulsymmetry at 12:18 PM on August 5
I LOVED Button Moon when I was a kid!! Brings back memories!
posted by cynical pinnacle at 5:53 PM on August 6, 2015 [1 favorite]
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