Explanation: What is that large dark spot on Jupiter? It's the shadow of Io, one of Jupiter's largest moons.
...
Unlike on Earth, moon shadows occur most days on Jupiter -- what's more unusual is that a spacecraft was close enough to record one with a high-resolutionimage.
There's a mix-up somewhere. "high-resolution" link says the moon is Ganymede.
A pessimist is nothing more than an experienced optimist
There is something strange with this picture. The diameter of the moon's shadow here appears to by about one fifth of the equatorial diameter of the planet, but the actual diameters are 5200 km and 143000 km respectively, a ratio or 1 to 27.5. How can this be?
(Is perhaps the neat circular shape of Jupiter in this picture an artifacts, a cropping or vignette of its full view?)
Roberto Molteni wrote: ↑Wed Apr 27, 2022 7:12 am
(... Is perhaps the neat circular shape of Jupiter in this picture an artifacts, a cropping or vignette of its full view?)
I wonder what effect the shadow has on the clouds and weather on Jupiter.
On Earth a total solar eclipse means the temperature drops noticeably for a few minutes, but we are a lot closer to the sun, so maybe this effect would not be so strong on Jupiter.
Roberto Molteni wrote: ↑Wed Apr 27, 2022 7:12 am
There is something strange with this picture. The diameter of the moon's shadow here appears to by about one fifth of the equatorial diameter of the planet, but the actual diameters are 5200 km and 143000 km respectively, a ratio or 1 to 27.5. How can this be?
(Is perhaps the neat circular shape of Jupiter in this picture an artifacts, a cropping or vignette of its full view?)
This picture demonstrates a common misunderstanding around Juno images. They are taken at far too low an altitude to show more than a fraction of Jupiter. Just like we can't see much of the Earth in images made from the ISS. Or an airplane. (Imagine what you'd get with a wide angle lens on a downward pointing camera mounted under an airplane. It would look like you were seeing the globe of the Earth, but you'd only be seeing to a horizon a few hundred miles away. And here, we're only seeing to a horizon a few thousand miles away.)
Chris
*****************************************
Chris L Peterson
Cloudbait Observatory https://www.cloudbait.com
Cool picture I've never seen before. This must be the month for unusual planet shadows. Here is a shadow from the solar system's largest moon. Not to be outdone one of the smallest moons is captured just this month eclipsing the Sun. Phobos. (Although this is the reverse of a shadow on the Sun.)
Roberto Molteni wrote: ↑Wed Apr 27, 2022 7:12 am
There is something strange with this picture. The diameter of the moon's shadow here appears to by about one fifth of the equatorial diameter of the planet, but the actual diameters are 5200 km and 143000 km respectively, a ratio or 1 to 27.5. How can this be?
(Is perhaps the neat circular shape of Jupiter in this picture an artifacts, a cropping or vignette of its full view?)
This picture demonstrates a common misunderstanding around Juno images. They are taken at far too low an altitude to show more than a fraction of Jupiter. Just like we can't see much of the Earth in images made from the ISS. Or an airplane. (Imagine what you'd get with a wide angle lens on a downward pointing camera mounted under an airplane. It would look like you were seeing the globe of the Earth, but you'd only be seeing to a horizon a few hundred miles away. And here, we're only seeing to a horizon a few thousand miles away.)
Yup. This confused the heck out of me too when I saw a similarly close-up image in another APOD months ago. This shot was taken from almost exactly one Jupiter radius away, and if you diagram it out, and draw tangents from a point one diameter away from a circle, it's easy to see the smaller disc you end up seeing:
close up view of Jupiter.JPG
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-- "To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."{ʲₒʰₙNYᵈₑᵉₚ}
I saw this movie. In a few moments millions of black rectangular objects will cover Jupiter causing it to implode and become a second star in our solar system.
johnnydeep wrote: ↑Wed Apr 27, 2022 8:58 pm
From the "moon shadows" link:
[ EDIT: hmm, the lyrics in the video don't match the "official" lyrics below. Guess he improvised here! ]
The lyrics I found do:
Moonshadow
Song by Cat Stevens (aka Yusuf Islam)
Yes, I'm being followed by a moonshadow
Moonshadow, moonshadow
Leaping and hopping on a moonshadow
Moonshadow, moonshadow
And if I ever lose my hands
Lose my plow, lose my land
Oh, if I ever lose my hands
Oh, if, I won't have to work no more
And if I ever lose my eyes
If my colours all run dry
Yes, if I ever lose my eyes
Oh, if, I won't have to cry no more
Yes, I'm being followed by a moonshadow
Moonshadow, moonshadow
Leaping and hopping on a moonshadow
Moonshadow, moonshadow
And if I ever lose my legs
I won't moan, and I won't beg
Oh, if I ever lose my legs
Oh, if, I won't have to walk no more
And if I ever lose my mouth
All my teeth, north and south
Yes, if I ever lose my mouth
Oh, if, I won't have to talk
Did it take long to find me?
I ask the faithful light
Oh, did it take long to find me?
And, are you gonna stay the night?
I'm being followed by a moonshadow
Moonshadow, moonshadow
Leaping and hopping on a moonshadow
Moonshadow, moonshadow
Moonshadow, moonshadow
Moonshadow, moonshadow
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk. — Garrison Keillor
LWL wrote: ↑Wed Apr 27, 2022 10:58 pm
I saw this movie. In a few moments millions of black rectangular objects will cover Jupiter causing it to implode and become a second star in our solar system.
2010: The Year We Make Contact (Odyssey Two)
ALL THESE WORLDS ARE YOURS — EXCEPT EUROPA ATTEMPT NO LANDING THERE.
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk. — Garrison Keillor
Roberto Molteni wrote: ↑Wed Apr 27, 2022 7:12 am
There is something strange with this picture. The diameter of the moon's shadow here appears to by about one fifth of the equatorial diameter of the planet, but the actual diameters are 5200 km and 143000 km respectively, a ratio or 1 to 27.5. How can this be?
(Is perhaps the neat circular shape of Jupiter in this picture an artifacts, a cropping or vignette of its full view?)
This picture demonstrates a common misunderstanding around Juno images. They are taken at far too low an altitude to show more than a fraction of Jupiter. Just like we can't see much of the Earth in images made from the ISS. Or an airplane. (Imagine what you'd get with a wide angle lens on a downward pointing camera mounted under an airplane. It would look like you were seeing the globe of the Earth, but you'd only be seeing to a horizon a few hundred miles away. And here, we're only seeing to a horizon a few thousand miles away.)
Yup. This confused the heck out of me too when I saw a similarly close-up image in another APOD months ago. This shot was taken from almost exactly one Jupiter radius away, and if you diagram it out, and draw tangents from a point one diameter away from a circle, it's easy to see the smaller disc you end up seeing:
close up view of Jupiter.JPG
Yes, I see the point.
Yet, even at a distance as close as one radius of Jupiter (77000 km) from the surface, the difference from 1:27.5 to 1:5 is not justified. There must be quite some cropping/vignetting (as also hinted by the very sharp edges of the planet's orb).
This picture demonstrates a common misunderstanding around Juno images. They are taken at far too low an altitude to show more than a fraction of Jupiter. Just like we can't see much of the Earth in images made from the ISS. Or an airplane. (Imagine what you'd get with a wide angle lens on a downward pointing camera mounted under an airplane. It would look like you were seeing the globe of the Earth, but you'd only be seeing to a horizon a few hundred miles away. And here, we're only seeing to a horizon a few thousand miles away.)
Yup. This confused the heck out of me too when I saw a similarly close-up image in another APOD months ago. This shot was taken from almost exactly one Jupiter radius away, and if you diagram it out, and draw tangents from a point one diameter away from a circle, it's easy to see the smaller disc you end up seeing:
close up view of Jupiter.JPG
Yes, I see the point.
Yet, even at a distance as close as one radius of Jupiter (77000 km) from the surface, the difference from 1:27.5 to 1:5 is not justified. There must be quite some cropping/vignetting (as also hinted by the very sharp edges of the planet's orb).
Yeah, it doesn't quite add up to me either. Even using the inner much darker portion of the shadow only seems to get the ratio to about 1:10. (I think your 1:5 was overestimating the Ganymede shadow width.) But I think the angular perspective makes a difference too: we clearly see an extreme horizontal shortening of the shadow. Is there any vertical lengthening going on?
-- "To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."{ʲₒʰₙNYᵈₑᵉₚ}
Moon Shadow on Jupiter
