Starship Asterisk*

Jupiter's Triple Shadow Transit

Explanation: This webcam and telescope image of banded gas giant Jupiter shows the transit of three shadows cast by Jupiter's moons in progress, captured in Belgian skies on October 12 at 0528 UT. Such a three shadow transit is a relatively rare event, even for a large planet with many moons. Visible in the frame are the three Galilean moons responsible, Callisto at the far left edge, Io closest to Jupiter's disk, and Europa below and just left of Io. Of their shadows on the sunlit Jovian cloud tops, Callisto casts the most elongated one near the planet's south polar region at the bottom. Io's shadow is above and right of Jupiter's Great Red Spot. Of course viewed from Jupiter's perspective, these shadow crossings could be seen as solar eclipses, analogous to the Moon's shadow crossing the sunlit face of planet Earth.

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Now everyone will be mooning over the freckles of Jupiter.

Bravo, this is a lovely and interesting picture! Unfortunately for those of us on the west coast of North America Jupiter was below the horizon during this triple shadow transit. There is some consolation in seeing a picture, but it's not quite the same thrill as seeing it for oneself in real time through the eyepiece of a telescope.

Nice Picture!!!

Would an observer see a total eclipse as we see one? Or would it be More Sun....or Less Sun....due to too far, or too close....and would it not be cool to hop in the old rocket, and go to the next eclipse???

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Boomer12k wrote:
Would an observer see a total eclipse as we see one? Or would it be More Sun....or Less Sun....due to too far, or too close....and would it not be cool to hop in the old rocket, and go to the next eclipse???

Our moon generally makes for much more interesting solar eclipses because it (often) just blocks the photosphere and allows us to see the corona in its full glory. These moons are an order of magnitude larger than the disk of the sun and would easily cover up the corona. They wouldn't even get all that dark because the moons would be illuminated by a strong Jupiter shine.

http://apod.nasa.gov/apod/ap120208.html
http://apod.nasa.gov/apod/ap130729.html
http://apod.nasa.gov/apod/ap121222.html

Beautiful photo. What kind of instrument was used to take this?

neufer wrote:

Boomer12k wrote:
Would an observer see a total eclipse as we see one? Or would it be More Sun....or Less Sun....due to too far, or too close....and would it not be cool to hop in the old rocket, and go to the next eclipse???

[b][color=#0000FF]Solar eclipse by Io with volcanic plumes[/color][/b]

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Our moon generally makes for much more interesting solar eclipses because it (often) just blocks the photosphere and allows us to see the corona in its full glory. These moons are an order of magnitude larger than the disk of the sun and would easily cover up the corona. They wouldn't even get all that dark because the moons would be illuminated by a strong Jupiter shine.

http://apod.nasa.gov/apod/ap120208.html
http://apod.nasa.gov/apod/ap130729.html
http://apod.nasa.gov/apod/ap121222.html

Plus, Jupiter is a gas giant, so on the visible surface of Jupiter there isn't any place stable to set up a telescope, and if you could find a deep solid surface, the sky would be obscured by clouds. Yep, give me good old Terra firma.

BongoBob wrote:Beautiful photo. What kind of instrument was used to take this?

A very modest setup. A small SCT with some simple secondary optics, and a video camera.

Planetary imaging doesn't require very exotic or expensive instrumentation, because you can select through hundreds or even thousands of video frames for the best images to combine. This lets you get around many of the tracking and seeing problems that plague long exposure astroimaging.

BongoBob wrote:Beautiful photo. What kind of instrument was used to take this?

British Astronomical Society wrote:The rare triple shadow transit of the Jovian Moons on 12th October was imaged by Leo Aerts. This series, starting 4h32 UT and ending 5h28 UT when clouds were rolling in again shows very well the triple transit, including the moons Io, Europe and Ganymede. Image taken with Celestron 9.25, 2.5x powermate projection, RGB filterset, dispersion corrector used together with a DMK21AU618 webcam.

The above description is from this page, which also provides a lovely sequence of images of this transit.

It is sobering to reflect that for having discovered these moons - defects in God's unchanging and perfect heavens - Galileo was sentenced to a life of house arrest by the Christian church.

Anthony Barreiro wrote:

British Astronomical Society wrote:The rare triple shadow transit of the Jovian Moons on 12th October was imaged by Leo Aerts. This series, starting 4h32 UT and ending 5h28 UT when clouds were rolling in again shows very well the triple transit, including the moons Io, Europe and Ganymede. Image taken with Celestron 9.25, 2.5x powermate projection, RGB filterset, dispersion corrector used together with a DMK21AU618 webcam.

The above description is from this page, which also provides a lovely sequence of images of this transit.

To be clear, the DMK21AU618 isn't really what most people would call a "webcam". It isn't an inexpensive camera with an integrated lens and color CMOS sensor, but rather, a high quality CCD camera designed to be used with an external lens, with a USB interface and capable of outputting uncompressed frames at a high rate.

this image is worth repeating on a future Sunday APOD with the predictable result of one of our descendants posting this image was posted way back in the 21st century.

Chris Peterson wrote:To be clear, the DMK21AU618 isn't really what most people would call a "webcam". It isn't an inexpensive camera with an integrated lens and color CMOS sensor, but rather, a high quality CCD camera designed to be used with an external lens, with a USB interface and capable of outputting uncompressed frames at a high rate.

Thanks for that, Chris. I was wondering what was meant by the reference to a webcam.

Rob

The explanation to the APOD states that the moons seen are Callisto, Io and Europa. However, in the information brought up through the "three shadows cast by Jupiter's moons" link it states the series "shows very well the triple transit, including the moons Io, Europe and Ganymede". I wonder therefore which of Callisto and Ganymede is the correct moon I assume that Europe may be a typing error unless it can be spelt Europa and also Europe.

DavidLeodis wrote:
The explanation to the APOD states that the moons seen are Callisto, Io and Europa. However, in the information brought up through the "three shadows cast by Jupiter's moons" link it states the series "shows very well the triple transit, including the moons Io, Europe and Ganymede". I wonder therefore which of Callisto and Ganymede is the correct moon

Callisto is the correct moon as the APOD states.

The 3 orbital resonance moons: Io, Europa & Ganymede can never be in alignment because Io/Europa (October) conjunctions are 180º out of phase with Europa/Ganymede (April) conjunctions.

Thanks neufer. Your help is appreciated.