Comments and questions about the
APOD on the main view screen.
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APOD Robot
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by APOD Robot » Thu Nov 30, 2023 5:05 am
Artemis 1: Flight Day 13
Explanation: On flight day 13 (November 28, 2022) of the Artemis I mission, the Orion spacecraft reached its maximum distance from its home world. Over 430,000 kilometers from Earth in a distant retrograde orbit, Orion surpassed the record for most distant spacecraft designed to carry humans. That record was previously set in 1970 during the
Apollo 13 mission to the Moon. Both Earth and Moon are in the
same field of view in this video frame from Orion on Artemis I mission flight day 13. The planet and its large natural satellite even appear about the same apparent size from the uncrewed
spacecraft's perspective.
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AVAO
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Post
by AVAO » Thu Nov 30, 2023 5:28 am
APOD Robot wrote: ↑Thu Nov 30, 2023 5:05 am
Artemis 1: Flight Day 13
Explanation: On flight day 13 (November 28, 2022) of the Artemis I mission, the Orion spacecraft reached its maximum distance from its home world. Over 430,000 kilometers from Earth in a distant retrograde orbit, Orion surpassed the record for most distant spacecraft designed to carry humans. That record was previously set in 1970 during the
Apollo 13 mission to the Moon. Both Earth and Moon are in the
same field of view in this video frame from Orion on Artemis I mission flight day 13. The planet and its large natural satellite even appear about the same apparent size from the uncrewed
spacecraft's perspective.
How could I place a NASA billboard 435,000 kilometers away, where I can quite accidentally also show the moon and earth together in the background? Great achievement by the NASA advertising team as well as the NASA engineers
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Techno_Caveman
Post
by Techno_Caveman » Thu Nov 30, 2023 9:09 am
Is the following statement correct: "Orion surpassed the record for most distant spacecraft designed to carry humans."? What about Apollo 10 LME Accent module which is currently in a heliocentric orbit and it actually had a crew in it at one stage! I am guessing it would be a contender to beat 430000km. I'm happy to be corrected.
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6thmoonofpluto
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by 6thmoonofpluto » Thu Nov 30, 2023 9:17 am
Don't want to brag or anything, but this photo was taken using a camera located on one of the solar arrays on the European Space Agency (ESA) supplied Orion European Service Module. So yes, huge plaudits to our friends in NASA, but kudos to ESA and its industrial partners too
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ZootMurph14
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by ZootMurph14 » Thu Nov 30, 2023 12:39 pm
Can someone explain why we can't see any of the MANY satellites around the Earth in these photos from space? I'd think we would almost have a ring at this time as we have so many orbiting our world.
Thanks!
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Roy
Post
by Roy » Thu Nov 30, 2023 12:53 pm
And why is it spelled VSVN? Unless aliens read right to left, then it is NVSV.
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Sa Ji Tario
Post
by Sa Ji Tario » Thu Nov 30, 2023 2:20 pm
Roy wrote: ↑Thu Nov 30, 2023 12:53 pm
And why is it spelled VSVN? Unless aliens read right to left, then it is NVSV.
Roy, turn 180º and you will read NASA
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Chris Peterson
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by Chris Peterson » Thu Nov 30, 2023 2:39 pm
ZootMurph14 wrote: ↑Thu Nov 30, 2023 12:39 pm
Can someone explain why we can't see any of the MANY satellites around the Earth in these photos from space? I'd think we would almost have a ring at this time as we have so many orbiting our world.
Thanks!
For the same reason we don't see any stars. It's a daytime image. Stars and satellites can't compete in brightness with the sunlit Earth, Moon, or capsule.
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Chris Peterson
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by Chris Peterson » Thu Nov 30, 2023 2:45 pm
Techno_Caveman wrote: ↑Thu Nov 30, 2023 9:09 am
Is the following statement correct: "Orion surpassed the record for most distant spacecraft designed to carry humans."? What about Apollo 10 LME Accent module which is currently in a heliocentric orbit and it actually had a crew in it at one stage! I am guessing it would be a contender to beat 430000km. I'm happy to be corrected.
Well... the APOD caption slightly misquotes NASA's claim, which is that the record is for "a spacecraft designed to carry humans to deep space and return safely to Earth." As the ascent module could not have survived re-entry, the claim is technically true.
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johnnydeep
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by johnnydeep » Thu Nov 30, 2023 4:55 pm
Chris Peterson wrote: ↑Thu Nov 30, 2023 2:39 pm
ZootMurph14 wrote: ↑Thu Nov 30, 2023 12:39 pm
Can someone explain why we can't see any of the MANY satellites around the Earth in these photos from space? I'd think we would almost have a ring at this time as we have so many orbiting our world.
Thanks!
For the same reason we don't see any stars. It's a daytime image. Stars and satellites can't compete in brightness with the sunlit Earth, Moon, or capsule.
But even if the light was right, wouldn't all the satellites be too tiny to see?
--
"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."{ʲₒʰₙNYᵈₑᵉₚ}
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johnnydeep
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by johnnydeep » Thu Nov 30, 2023 4:57 pm
APOD wrote:The planet and its large natural satellite even appear about the same apparent size
Hardly. The Earth is only about 60% of the size of the Moon here!
--
"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."{ʲₒʰₙNYᵈₑᵉₚ}
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Chris Peterson
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by Chris Peterson » Thu Nov 30, 2023 5:04 pm
johnnydeep wrote: ↑Thu Nov 30, 2023 4:55 pm
Chris Peterson wrote: ↑Thu Nov 30, 2023 2:39 pm
ZootMurph14 wrote: ↑Thu Nov 30, 2023 12:39 pm
Can someone explain why we can't see any of the MANY satellites around the Earth in these photos from space? I'd think we would almost have a ring at this time as we have so many orbiting our world.
Thanks!
For the same reason we don't see any stars. It's a daytime image. Stars and satellites can't compete in brightness with the sunlit Earth, Moon, or capsule.
But even if the light was right, wouldn't all the satellites be too tiny to see?
So are stars. So are satellites to our eyes on the ground. "Seeing" isn't the same as "resolving". We see point sources as long as they send enough photons our way to rise above the background noise. To see satellites in an image like this, we'd have to expose long enough to show stars. And while there would be satellites in the image (although the glare from the hugely overexposed Earth might be a problem), I don't know that we could distinguish them from stars. After all, we look up at the sky from the ground and unless they're moving, can't readily identify satellites.
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Ann
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Post
by Ann » Thu Nov 30, 2023 5:22 pm
johnnydeep wrote: ↑Thu Nov 30, 2023 4:57 pm
APOD wrote:The planet and its large natural satellite even appear about the same apparent size
Hardly. The Earth is only about 60% of the size of the Moon here!
You beat me to it, Johnny!
Ann
Color Commentator
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Ann
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by Ann » Thu Nov 30, 2023 5:23 pm
AVAO wrote: ↑Thu Nov 30, 2023 5:28 am
APOD Robot wrote: ↑Thu Nov 30, 2023 5:05 am
Artemis 1: Flight Day 13
Explanation: On flight day 13 (November 28, 2022) of the Artemis I mission, the Orion spacecraft reached its maximum distance from its home world. Over 430,000 kilometers from Earth in a distant retrograde orbit, Orion surpassed the record for most distant spacecraft designed to carry humans. That record was previously set in 1970 during the
Apollo 13 mission to the Moon. Both Earth and Moon are in the
same field of view in this video frame from Orion on Artemis I mission flight day 13. The planet and its large natural satellite even appear about the same apparent size from the uncrewed
spacecraft's perspective.
How could I place a NASA billboard 435,000 kilometers away, where I can quite accidentally also show the moon and earth together in the background? Great achievement by the NASA advertising team as well as the NASA engineers
Right you are, Jac!
Ann
Color Commentator
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leofish1
- Asternaut
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Post
by leofish1 » Thu Nov 30, 2023 5:36 pm
I know there is no "up" in space, but the photo is oriented with Earth's south pole at the top. All the white at the top is Antarctica which was nearing its summer solstice.
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Chris Peterson
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by Chris Peterson » Thu Nov 30, 2023 6:05 pm
leofish1 wrote: ↑Thu Nov 30, 2023 5:36 pm
I know there is no "up" in space, but the photo is oriented with Earth's south pole at the top. All the white at the top is Antarctica which was nearing its summer solstice.
There may be no up in space, but there is certainly a convention for up in the Solar System, which is North.
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johnnydeep
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by johnnydeep » Thu Nov 30, 2023 7:32 pm
Chris Peterson wrote: ↑Thu Nov 30, 2023 5:04 pm
johnnydeep wrote: ↑Thu Nov 30, 2023 4:55 pm
Chris Peterson wrote: ↑Thu Nov 30, 2023 2:39 pm
For the same reason we don't see any stars. It's a daytime image. Stars and satellites can't compete in brightness with the sunlit Earth, Moon, or capsule.
But even if the light was right, wouldn't all the satellites be too tiny to see?
So are stars. So are satellites to our eyes on the ground. "Seeing" isn't the same as "resolving". We see point sources as long as they send enough photons our way to rise above the background noise. To see satellites in an image like this, we'd have to expose long enough to show stars. And while there would be satellites in the image (although the glare from the hugely overexposed Earth might be a problem), I don't know that we could distinguish them from stars. After all, we look up at the sky from the ground and unless they're moving, can't readily identify satellites.
Thanks. So would you say it's reasonable to think that the photons reflected Orion's way from satellites orbiting the Earth 430,000 away is within an order of magnitude of the photon flux it would receive from a Sun-like star a hundred light years away? Math would help of course, but what would you guesstimate?
--
"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."{ʲₒʰₙNYᵈₑᵉₚ}
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Chris Peterson
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by Chris Peterson » Thu Nov 30, 2023 8:07 pm
johnnydeep wrote: ↑Thu Nov 30, 2023 7:32 pm
Chris Peterson wrote: ↑Thu Nov 30, 2023 5:04 pm
johnnydeep wrote: ↑Thu Nov 30, 2023 4:55 pm
But even if the light was right, wouldn't all the satellites be too tiny to see?
So are stars. So are satellites to our eyes on the ground. "Seeing" isn't the same as "resolving". We see point sources as long as they send enough photons our way to rise above the background noise. To see satellites in an image like this, we'd have to expose long enough to show stars. And while there would be satellites in the image (although the glare from the hugely overexposed Earth might be a problem), I don't know that we could distinguish them from stars. After all, we look up at the sky from the ground and unless they're moving, can't readily identify satellites.
Thanks. So would you say it's reasonable to think that the photons reflected Orion's way from satellites orbiting the Earth 430,000 away is within an order of magnitude of the photon flux it would receive from a Sun-like star a hundred light years away? Math would help of course, but what would you guesstimate?
Well, the Sun from 100 ly away would have an apparent magnitude of about 7. Most geosynchronous satellites I capture when imaging near the celestial equator are around mag 12, so about 100 times dimmer than that. But they can flare up to mag 5 or 6. So broadly, we could consider high orbit satellites to be similar to nearby Sun-like stars.
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johnnydeep
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by johnnydeep » Thu Nov 30, 2023 9:14 pm
Chris Peterson wrote: ↑Thu Nov 30, 2023 8:07 pm
johnnydeep wrote: ↑Thu Nov 30, 2023 7:32 pm
Chris Peterson wrote: ↑Thu Nov 30, 2023 5:04 pm
So are stars. So are satellites to our eyes on the ground. "Seeing" isn't the same as "resolving". We see point sources as long as they send enough photons our way to rise above the background noise. To see satellites in an image like this, we'd have to expose long enough to show stars. And while there would be satellites in the image (although the glare from the hugely overexposed Earth might be a problem), I don't know that we could distinguish them from stars. After all, we look up at the sky from the ground and unless they're moving, can't readily identify satellites.
Thanks. So would you say it's reasonable to think that the photons reflected Orion's way from satellites orbiting the Earth 430,000 away is within an order of magnitude of the photon flux it would receive from a Sun-like star a hundred light years away? Math would help of course, but what would you guesstimate?
Well, the Sun from 100 ly away would have an apparent magnitude of about 7. Most geosynchronous satellites I capture when imaging near the celestial equator are around mag 12, so about 100 times dimmer than that. But they can flare up to mag 5 or 6. So broadly, we could consider high orbit satellites to be similar to nearby Sun-like stars.
Nice guesstimating!
--
"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."{ʲₒʰₙNYᵈₑᵉₚ}
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Sa Ji Tario
Post
by Sa Ji Tario » Fri Dec 01, 2023 4:43 am
Techno_Caveman wrote: ↑Thu Nov 30, 2023 9:09 am
Is the following statement correct: "Orion surpassed the record for most distant spacecraft designed to carry humans."? What about Apollo 10 LME Accent module which is currently in a heliocentric orbit and it actually had a crew in it at one stage! I am guessing it would be a contender to beat 430000km. I'm happy to be corrected.
My friend Ernesto tells me that "...the Apollo 10 lunar module is in orbit around the Sun, in an unknown place, it must certainly be at a greater distance, perhaps they do not include it in this record due to the fact that there is no record, because its current location is unknown..."
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alter-ego
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by alter-ego » Fri Dec 01, 2023 5:19 am
johnnydeep wrote: ↑Thu Nov 30, 2023 4:57 pm
APOD wrote:The planet and its large natural satellite even appear about the same apparent size
Hardly. The Earth is only about 60% of the size of the Moon here!
Yes. In fact, about 4 hrs prior to the image, the moon occulted the Earth for about 77 minutes.
Correction: Occultation starts 3.6 hours prior; duration 52 minutes.
A pessimist is nothing more than an experienced optimist
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beryllium732
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by beryllium732 » Sun Dec 03, 2023 10:36 pm
Chris Peterson wrote: ↑Thu Nov 30, 2023 2:39 pm
ZootMurph14 wrote: ↑Thu Nov 30, 2023 12:39 pm
Can someone explain why we can't see any of the MANY satellites around the Earth in these photos from space? I'd think we would almost have a ring at this time as we have so many orbiting our world.
Thanks!
For the same reason we don't see any stars. It's a daytime image. Stars and satellites can't compete in brightness with the sunlit Earth, Moon, or capsule.
If we removed those light sources would the stars surrounding us be crystal clear? Would we be able to see the galactic disc?
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Chris Peterson
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by Chris Peterson » Sun Dec 03, 2023 10:52 pm
beryllium732 wrote: ↑Sun Dec 03, 2023 10:36 pm
Chris Peterson wrote: ↑Thu Nov 30, 2023 2:39 pm
ZootMurph14 wrote: ↑Thu Nov 30, 2023 12:39 pm
Can someone explain why we can't see any of the MANY satellites around the Earth in these photos from space? I'd think we would almost have a ring at this time as we have so many orbiting our world.
Thanks!
For the same reason we don't see any stars. It's a daytime image. Stars and satellites can't compete in brightness with the sunlit Earth, Moon, or capsule.
If we removed those light sources would the stars surrounding us be crystal clear? Would we be able to see the galactic disc?
The problem isn't the presence of the light sources. It's that the camera exposure is set for them. To see the stars and Milky Way the camera exposure would need to be set just like we do taking night sky pictures on the ground- high ISO and at least a few seconds exposure time. The stars don't look much different in space than they do from any dark location on the ground.