Starship Asterisk*

VictorBorun wrote: ↑Mon Aug 23, 2021 6:58 am
At its starting moment there was a synestia, so Earth's equatorial velocity must have been almost equal to the low orbit velocity about 7 km/s, and Moon was in an almost low orbit. Then the tidal interaction stopped Moon's spin down to the tidal lock and slowed Earth's spin down to the period of 24 hours and the equatorial velocity of 0.46 km/s; the total spin is preserved by Moon's escaping to a high orbit where Moon's orbital radius is longer and, though Moon's orbital velocity is slower, still Moon's orbital spin is higher.

This today's configuration is many times slower and, though the two velocities (Moon's orbital and Earth's equatorial) are not like each other any more they both are now so slow that we can get on a plane and freeze Moon against the superlunar sky.

neufer wrote: ↑Sun Aug 22, 2021 4:35 pm

https://en.wikipedia.org/wiki/Solar_eclipse_of_June_30,_1973 wrote: One of the planes was a prototype of what was later to become the Concorde, which has a top speed of almost 0.606 km/s. This enabled scientists from Los Alamos, the Paris Observatory, the Kitt Peak National Observatory, Queen Mary University of London, the University of Aberdeen and CNRS to extend totality to more than 74 minutes; nearly 10 times longer than is possible when viewing a total solar eclipse from a stationary location.

VictorBorun wrote: ↑Sun Aug 22, 2021 10:06 am
I can see that the velocity of the Ganymede's & Europa's shadows are similar to the velocity of the Jupiter's surface.

This does not mean that the satellites are almost stationary in Jupiter's sky though.
This only means that the satellites move slowly in relataion to Sun in Jupiter's sky.

equatorial rotation velocity of Jupiter is 12.6 km/s. It is in-between:
orbital velocity of Europa is 13.7 km/s; that is faster by 1.1 km/s
orbital velocity of Ganymede is 10.880 km/s; that is slower by 1.72 km/s

We are more lucky with Moon-Sun dance:

equatorial rotation velocity of Earth is 0.46 km/s
orbital velocity of Moon is 0.970 to 1.082 km/s in plane at 5.145° to the equatorial plane of Earth;
that is faster just by 0.51…0.622 km/s, and can be outrun by a supersonic plane

https://en.wikipedia.org/wiki/Solar_eclipse_of_June_30,_1973 wrote:

Solar eclipse of June 30, 1973

---

<<A total solar eclipse occurred at the Moon's descending node of the orbit on June 30, 1973. With a maximum eclipse of 7 minutes and 3.55 seconds, this was the last total solar eclipse that exceeds 7 minutes in this series. The last total eclipse over 7 minutes was on July 1, 1098 which lasted 7 minutes and 5 seconds. There will not be a longer total solar eclipse until June 25, 2150. The greatest eclipse occurred in the Agadez area in the northwest of Niger not far from Algeria inside the Sahara Desert somewhat 40 km east of the small mountain of Ebenenanoua at 18.8 N and 5.6 E and occurred at 11:38 UTC.

This eclipse was observed by a group of scientists, which included Donald Liebenberg, from the Los Alamos National Laboratory. They used two airplanes to extend the apparent time of totality by flying along the eclipse path in the same direction as the Moon's shadow as it passed over Africa.

One of the planes was a prototype of what was later to become the Concorde, which has a top speed of almost 0.606 km/s. This enabled scientists from Los Alamos, the Paris Observatory, the Kitt Peak National Observatory, Queen Mary University of London, the University of Aberdeen and CNRS to extend totality to more than 74 minutes; nearly 10 times longer than is possible when viewing a total solar eclipse from a stationary location. That Concorde was specially modified with rooftop portholes for the mission, and is currently on display with the Solar Eclipse mission livery at Musée de l’air et de l’espace. The data gathered resulted in three papers published in Nature and a book.

A separate observation opportunity was provided on a specialized commercial cruise by the S.S. Canberra, which traveled from New York City to the Canary Islands and Dakar, Senegal, observing 5 minutes and 44 seconds of totality out in the Atlantic between those two stops in Africa. That cruise's passengers included notables in the scientific community such as Neil Armstrong, Scott Carpenter, Isaac Asimov, Walter Sullivan, and the then 15-years old Neil deGrasse Tyson.>>

jks wrote: ↑Sat Aug 21, 2021 5:09 am In the '70's, I loved watching transits of the Jovian moons' shadows, and transits of the moons themselves on Jupiter's disk but for some reason I was never able to see a moon eclipse another, much less on Jupiter's disk, as seen from Earth. But I was able to see one moon occult another on more than one occasion.

Here's to the Criterion Dynascope 6 (circa 1975)* !

* I'm pretty sure that I am not violating Rule #8, or if I am, I'm 46 years too late ).

Joe Stieber wrote: ↑Sat Aug 21, 2021 10:45 pm

johnnydeep wrote: ↑Sat Aug 21, 2021 9:17 pm

Joe Stieber wrote: ↑Sat Aug 21, 2021 5:52 pm
Okay, here's my annotated version. I labeled the satellites as I, E, G and C for Io, Europa, Ganymede and Callisto respectively. When followed by an S, it's that satellite's shadow. I used FastStone to do the labeling and WinJUPOS as my satellite/shadow position reference. This is a remarkable set of images showing some rare configurations!
J20210815a_cgo-label.jpg
Joe

Thanks! In the fourth pic of Jupiter, GS points to two shadows. It should only point to the larger one, right?

No -- the two arrows are correct. The top of Europa intercepts the bottom of Ganymede's shadow (a partial eclipse), then the rest of shadow continues to the Jovian surface where it mingles with Europa's shadow. Here's a close-up clip of the WinJUPOS synthetic image for Aug 15 @ 17:25 UT. Pretty amazing!
2021-08-15-1725.0-Jupiter-NR.png
Joe

P.S. -- The dashed line in the WinJUPOS clip represents Jupiter's equator.

Joe Stieber wrote: ↑Sat Aug 21, 2021 5:52 pm Okay, here's my annotated version. I labeled the satellites as I, E, G and C for Io, Europa, Ganymede and Callisto respectively. When followed by an S, it's that satellite's shadow. I used FastStone to do the labeling and WinJUPOS as my satellite/shadow position reference. This is a remarkable set of images showing some rare configurations!
J20210815a_cgo-label.jpg
Joe

johnnydeep wrote: ↑Sat Aug 21, 2021 9:17 pm

Joe Stieber wrote: ↑Sat Aug 21, 2021 5:52 pm

johnnydeep wrote: ↑Sat Aug 21, 2021 4:07 pm Deciphering the description to determine what's what (moon, shadow, "mutual event") in each panel pains me. Who wants to annotate it?

Okay, here's my annotated version. I labeled the satellites as I, E, G and C for Io, Europa, Ganymede and Callisto respectively. When followed by an S, it's that satellite's shadow. I used FastStone to do the labeling and WinJUPOS as my satellite/shadow position reference. This is a remarkable set of images showing some rare configurations!
J20210815a_cgo-label.jpg
Joe

Thanks! In the fourth pic of Jupiter, GS points to two shadows. It should only point to the larger one, right?

Joe Stieber wrote: ↑Sat Aug 21, 2021 5:52 pm

johnnydeep wrote: ↑Sat Aug 21, 2021 4:07 pm Deciphering the description to determine what's what (moon, shadow, "mutual event") in each panel pains me. Who wants to annotate it?

Okay, here's my annotated version. I labeled the satellites as I, E, G and C for Io, Europa, Ganymede and Callisto respectively. When followed by an S, it's that satellite's shadow. I used FastStone to do the labeling and WinJUPOS as my satellite/shadow position reference. This is a remarkable set of images showing some rare configurations!
J20210815a_cgo-label.jpg
Joe

johnnydeep wrote: ↑Sat Aug 21, 2021 4:07 pm Deciphering the description to determine what's what (moon, shadow, "mutual event") in each panel pains me. Who wants to annotate it?