Jupiter and Four Moons

Jupiter and Four Moons title=
Jupiter and Four Moons
Reads 6229

By Chuck Cagara

REPORT FROM THE FIELD: Sierra Nevada Foothills, California, USA

August 4, 2020

After spending some time in July enjoying and photographing Comet NEOWISE, I decided that it was time to turn to the telescope and have a gander at two of the easier targets in the night sky - gas giants Jupiter and Saturn.

If you follow astronomy you'll know that when two astronomers meet they ask of each other, "So, how was the seeing tonight?"

By 'seeing' they want to know if the night air was both clear and stable, so as to give the sharpest view possible through their telescopes.  Poor seeing occurs when hot daytime temperatures produce heat waves that rise and are amplified when viewed at the powerful magnifications needed to gain attractive views of the planets.  So too, is the seeing poor, when weather conditions bring haze or some cloudiness to your local sky at the time of your observations.

Note that during times of poor seeing, all is not always lost - for brief flickering moments the air may become just stable enough to enjoy a crisp, fleeting view of Jupiter's great red spot or the Cassini Division of Saturn's ring system.

So, on this hot August night (daytime high was 98°) knowing the seeing would be questionable, I hauled out the 8" Meade Schmidt-Cassegrain telescope and attached a camera to it.  This method of astrophotography, where the camera attaches directly to the tube is known as 'prime focus' photography.

Alas, as expected, the seeing was generally poor and the planets were mostly blurry discs without clarity or detail.

However, we did manage several photos taken at just those moments when the seeing improved for a fleeting moment.

Here is the best of the lot clearly showing the marbled face of Jupiter along with four of its seventy-nine moons.  From left to right they are Io, Europa, Ganymede and Callisto.  These are called the 'Galilean Moons' because they were first seen and described through his crude telescope by Galileo in 1610.

And now, from the 1951 movie, "The Thing from Another World," I exhort you to:

"Watch the skies. Everywhere. Keep looking. Keep watching the skies."

Over and out for now...

Login to add Comments


Show Comments
EastBeach Aug 09, 2020 10:24 PM
Jupiter and Four Moons

Very nice image! Speaking of Europa ... Raytheon Vision Systems in Goleta will have an imaging sensor on the E-Themis instrument package that will fly on the Europa Clipper mission in 2025.

macpuzl Aug 09, 2020 07:41 PM
Jupiter and Four Moons

Not to detract from the quality of the image, but if it was taken on the night of August 4, the configuration of the moons from left to right was Callisto, Ganymede, Io, and Europa. Ganymede is the biggest moon in the solar system, bigger than the planet Mercury. Io is full of volcanos. Europa is an ice ball with a liquid salt water ocean containing more water than there is in the oceans on Earth.

Curmudgeon Aug 09, 2020 07:52 PM
Jupiter and Four Moons

Yes, MACPUZL, I caught that after the fact. Again, thanks for further elucidation - good info.

macpuzl Aug 09, 2020 07:23 PM
Jupiter and Four Moons

Nice view of Jupiter!

Often the sky conditions for astronomical observing are described in three categories:

Cloud cover - The obvious cloud and fog that appear whenever a telescope is set up.
Seeing - Scintillation (twinkle) caused by winds, often at high altitude, like the jet stream.
Transparency - Haze or water vapor content that may dim the view without totally occluding it.

Often, hazy conditions have very good seeing, because the air mass is still. Bad seeing may be fast, which manifests as rapid twinkling, or slow, which manifests as an object appearing to move slightly while remaining largely in focus.

You can get local predictions for these conditions from the Clear Sky Chart (https://www.cleardarksky.com/csk/) or from Astrospheric (https://www.astrospheric.com/).

Curmudgeon Aug 09, 2020 07:39 PM
Jupiter and Four Moons

Thanks, MACPUZL, for your comment and additional elucidation. Appreciated.

mtndriver Aug 09, 2020 06:12 PM
Jupiter and Four Moons

I wondered about that, Curmudgeon! Hope the "seeing" is good tonight!
Edhat, you need to change that headline!

Curmudgeon Aug 09, 2020 05:22 PM
Jupiter and Four Moons

OP here: Since I have not read my horoscope today it should be noted that I have submitted an ASTRONOMICAL report, not an 'astrological' report as the weekend EdHat editor has suggested.

Please Login or Register to comment on this.