APOD: Caterpillar Moon (2013 May 24)

[APOD Robot]

Caterpillar Moon

Explanation: A close series of consecutive exposures are combined in this intriguing composite of the Full Moon slowly crawling, across the sky. Beginning on the upper right at 19:42 UT and ending at 22:14 UT on April 25, the sequence follows the Moon from Germany as it passes through Earth's shadow in a partial lunar eclipse. Near the top, the Moon just grazes the southern edge of Earth's dark central shadow, or umbra. But the decreased brightness in the darker part of the outer shadow region, the penumbra, is also apparent on the lunar disk. In fact, the relative size and shape of the Earth's shadow regions and the Moon are easier to see along the segments of this lunar caterpillar. Nearly impossible to follow with the eye though, a penumbral lunar eclipse, the Full Moon passing only through the pale outer penumbral shadow, will begin on May 25.

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[Beyond]

Caterpillar Moon?? NAH!! How about Moontube? . . The first link -across the sky- is a 404.

[owlice]

Thanks, Beyond; I'll let TPTB know. I think it is supposed to go here.

[MargaritaMc]

What an intriguing picture! As it opened in my browser I thought for a moment that it was a roll of BUBBLE WRAP!
Margarita

[Boomer12k]

Huh....interesting way of depicting a Lunar Eclipse...most are side by side images of progression, and stuff...very creative....

:---[===] *

[Boomer12k]

What an intriguing picture! As it opened in my browser I thought for a moment that it was a roll of BUBBLE WRAP!
Margarita

Reminded me of a Cigarette or something, but a roll of bubble wrap works....

:---[===] *

[emc]

Interesting image taking!

But the Moon is no slug (or creepy crawly caterpillar) traveling at well over twice and not far from three times the speed of sound... sound that it isn’t making since it has no medium for sound to travel through in outer space.

[Chris Peterson]

But the Moon is no slug (or creepy crawly caterpillar) traveling at well over twice and not far from three times the speed of sound... sound that it isn’t making since it has no medium for sound to travel through in outer space.

And yet... there is a medium in space, and sound does travel through it. All those fantastic nebula and SNR remnant images we see on this forum look as they do because of the passage of sound through them. That is the primary mechanism that forms their structure.

The Moon makes a sound that carries through space. It's not very loud, for sure, but it's there if you have the right ears to pick it up.

[emc]

Hi Chris, When you say that nebula and SNR remnants look as they do because of sound passing through them, are you referring to stimuli such as other SNs or do the sound waves coincide with the SN within its own medium? And is the “right ears” placing a radio transmitter on the surface of the moon?

[Chris Peterson]

Hi Chris, When you say that nebula and SNR remnants look as they do because of sound passing through them, are you referring to stimuli such as other SNs or do the sound waves coincide with the SN within its own medium? And is the “right ears” placing a radio transmitter on the surface of the moon?

All of those shock waves we see in nebulas are essentially created by sound- particles transferring momentum to adjacent particles, in a cascade. The sound energy may be local, or it may be external.

You listen to sound with a microphone- a device that records changes in the pressure of a medium. In a near vacuum, you would do that by literally counting particle collisions with a sensor. No EM devices like radios are involved.

[flash]

And yet... there is a medium in space, and sound does travel through it. All those fantastic nebula and SNR remnant images we see on this forum look as they do because of the passage of sound through them. That is the primary mechanism that forms their structure.

The Moon makes a sound that carries through space. It's not very loud, for sure, but it's there if you have the right ears to pick it up.

Just to clarify: Some of the structures we see are no doubt "sound" generated: individual molecules colliding and rebounding in waves of changing densities causing shock waves, etc... But surely not "All those fantastic nebula and SNR remnant images we see on this forum look as they do because of the passage of sound through them": Pillars of Creation are being "eroded" or "evaporated" by incident radiation, not sound. Clouds of gas glow becuase they are ionized by energetic radiation or they reflect radiation. Stars glow because of gravity and nuclear processes. The primary mechanisms that form their structure (at least what we can observe) are gravity and electromagnetic radiation. Yes?

[emc]

Hi Chris, When you say that nebula and SNR remnants look as they do because of sound passing through them, are you referring to stimuli such as other SNs or do the sound waves coincide with the SN within its own medium? And is the “right ears” placing a radio transmitter on the surface of the moon?

All of those shock waves we see in nebulas are essentially created by sound- particles transferring momentum to adjacent particles, in a cascade. The sound energy may be local, or it may be external.

You listen to sound with a microphone- a device that records changes in the pressure of a medium. In a near vacuum, you would do that by literally counting particle collisions with a sensor. No EM devices like radios are involved.

I get nebula as a sound medium.

So the Moon makes sound as it hits particles in space. So if the Moon were the right type of sensor, we would hear it moving through space. How would the sensor broadcast to our ears?... or is that a silly question?

[Chris Peterson]

I get nebula as a sound medium.

So the Moon makes sound as it hits particles in space. So if the Moon were the right type of sensor, we would hear it moving through space. How would the sensor broadcast to our ears?... or is that a silly question?

Well, if I were making a sensor to listen to the near Earth environment, I'd probably stretch some sort of large, thin membrane in a frame and put something like a piezoelectric sensor on it to count "pings". Once I had an event list, I could convert that to sound in the range our ears can hear, like people do with starquakes and other sorts of mechanical vibration that need to be detected and converted before we can hear them.

[emc]

Sounds cool! (no pun intended… this time) I would love to hear the Moon!

[emc]

if the moon were to speak
would we be humbled
all those howlings
rebounding

[neufer]

So the Moon makes sound as it hits particles in space. So if the Moon were the right type of sensor, we would hear it moving through space. How would the sensor broadcast to our ears?... or is that a silly question?

http://apod.nasa.gov/apod/ap101010.html
http://science1.nasa.gov/science-news/s ... oonquakes/

<<A moonquake is the lunar equivalent of an earthquake (i.e., a quake on the Moon). They were first discovered by the Apollo astronauts. Moonquakes are much weaker than the largest earthquakes, though they can last for up to an hour, due to the lack of water to dampen seismic vibrations. Information about moonquakes comes from seismometers placed on the Moon by Apollo astronauts from 1969 through 1972. The instruments placed by the Apollo 12, 14, 15 and 16 functioned perfectly until they were switched off in 1977.

According to NASA, there are at least four different kinds of moonquakes:

• Deep moonquakes (~700 km below the surface, probably tidal in origin)
  Meteorite impact vibrations
  Thermal moonquakes (the frigid lunar crust expands when sunlight returns after the two week lunar night)
  Shallow moonquakes (20 or 30 kilometers below the surface)

The first three kinds of moonquakes mentioned above tend to be mild; however, shallow moonquakes can register up to 5.5 on the Richter scale. Between 1972 and 1977, twenty-eight shallow moonquakes were observed. On Earth, quakes of magnitude 4.5 and above can cause damage to buildings and other rigid structures.>>

[BMAONE23]

Sounds cool! (no pun intended… this time) I would love to hear the Moon!

if the moon were to speak
would we be humbled
all those howlings
rebounding

Click to play embedded YouTube video.

Your wish is granted (and corrupted)

[emc]

So if we stuck a microphone in the Moon, we might hear it rumble and grumble... from famishment and physics... for bakes and quakes

[neufer]

Click to play embedded YouTube video.

Published on Apr 1, 2013

Hope wrote a song that names all of the natural satellites (moons) in our solar system, based off of Tom Lehrer's, The Elements Song.

There's amalthea n halimede adrastea prometheus
n eurydome enceladus n harpalyke puck proteus
ophelia cordelia titania n oberon
miranda nix n hydra n laomedia n rhea bebionn
sponde n kale larissa sycorax n desdemona moon
n thelxinoe dysnomia n ferdinand n themisto
n prospero albiorix n stepheno n callirrhoe
n ariel n cressida n skoll charon n callisto

There's polyduces praxidike n eukelade n ganymede
epimethus n kallichore himalia and farbauti
hyperion greip hyrrokkin n rosalind n belinda n autonoe n suttungr n methone arche n pandora

There's cyllene thebe herse setebos n chaldene kore ymir calypso
n iocaste n isonoe n erinome n telesto
n pasiphae n hegemone n jarnxasa erriapus
n daphnis aegir sinope neso mundilfari loge metis
there's megaclite n pasithee n thalassa n galatea
n umbriel n margaret and francisco n euporie
n siarnaq carme mab paaliaq iapetus n europa
n bergelmir n thyone anthe n elara n perdita

There's phobos deimos io carpo bestla sao n aoede
aitne kalyke hermippe leda tethys n skathi hati
n helike janus phoebe titan taygete mnene n orthosie
n mimas tarvos kiviuq tarqeq thrymr narvi euanthe

Theres ananke lysithea n dione helene nerid
n atlas fornjot fenrir pallene ijiraqq cupid naiad
n juliet portia aegaeon caliban namka triton hiaka sutur kari bianca trinculo psamathe pan

These are the only natural satellites of which are in our solar system plus despina and weird numbered ones of which i could not all fit in!

[mjimih]

now who would make a 10 min video that repeats every 2 seconds?!

try this ~10 min video! Skip to the 6 min mark for the moon face in action.

Click to play embedded YouTube video.

[geckzilla]

now who would make a 10 min video that repeats every 2 seconds?!

They're actually pretty common. I have a theory that it somehow relates to some form of recreational drug use...

[Chris Peterson]

So if we stuck a microphone in the Moon, we might hear it rumble and grumble... from famishment and physics... for bakes and quakes

Yeah, but there we're talking about sound carried through a solid (and that's actually been recorded on the Moon). But moonquakes also transfer energy (a small, but finite amount) to the thin interplanetary medium, which is then carried as sound waves in a gas. It is probably beyond our technology to detect them that way, but that doesn't mean those sound waves aren't there.

[alter-ego]

Near the top, the Moon just grazes the southern edge of Earth's dark central shadow, or umbra.

Regarding this APOD, the graze condition provides a very nice view of the penumbral shadow gradient. Although the image gives the impression of a deeper partial, it is not. The umbral edge overlaps the moon by only 3% (1 arcminute). In fact the image reveals nothing of the umbral shadow edge at all. The shadow gradient is entirely due to the penumbra, and for this image, the moon is the viewing screen for only the penumbra. This image very nicely shows a shadow gradient that is purely geometric in origin and is close to what would be viewed on a surface of uniform reflectance. Typically lunar reflectance differences, image exposures, and sometimes image post-processing, significantly change the gradient shape, i.e. the imaged gradient does not map linearly to the incident solar flux across the entire lunar surface. For this image, the many overlapping moon images tend to homogenize the lunar surface appearance and make the effective reflectance more uniform. This then tends to reduce the visible variations in shadow contrast and permits a better view of the penumbral gradient.

I think this is image is a wonderful example for visualizing the incident solar flux gradient in only the penumbral region.

[fausto.lubatti]

A very different way of representing the eclipse: well done!