Of Particular Significance

Moon and Jupiter Galileo-Style, ***This Evening***

POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON 01/15/2014

If you have a clear sky, don’t forget to look overhead tonight!  And go get your binoculars or small telescope…

After an overnight flight and a train that brought me to Florence (Firenze), Italy, where I’ll be teaching this week, I decided to fight off sleep by taking a walk down into the city and wandering around for a while.  It was a beautiful evening, with deep blue twilight.  And it wasn’t long before the planet Jupiter, and then the full Moon, rose above the buildings and high into the sky.  I caught a photo of them, between the Duomo (cathedral) and its campanile (bell tower).  Jupiter is the little white dot directly above the moon, at the top of the second set of windows on the campanile.

The Moon and Jupiter (tiny dot well above the Moon) shine between the Duomo of Florence (left) and its Campanile. Photo credit: Matt Strassler

I then pulled out my binoculars, which aren’t quite as powerful as Galileo’s telescope was 400 years ago, but are still enough to reveal what Galileo discovered.  Just as Galileo (and his competitor Thomas Herriot) did in 1609, I could see all sorts of structure to the Moon’s surface, including what we now know are basalt plains, and hints of impact craters.  [Admittedly, impact craters and mountains are actually easiest to see when the Moon isn’t full, because then the shadows that mountains cast are longer.]

And looking at Jupiter, which is relatively close to Earth right now, I could easily see that it was a disk, not a dot like a star, and that there are three dim dots, sitting in a line that passes through the planet.  These are three of Jupiter’s four large moons: Callisto, Ganymede, Europa and Io.  [The fourth one might well be visible if you’re lucky and have good eyes and good timing.]  If you watch them day by day, they will change position, a fact that Galileo used to guess they were moons orbiting Jupiter.

So if you have good weather, tonight’s a great opportunity for some simple but very satisfying astronomy.  Don’t miss the naked-eye view that’s on offer right now or in a few hours, depending on where you reside.  And if you’ve got binoculars handy, you can relive Galileo’s remarkable discoveries about the Moon and Jupiter, and contemplate how the first telescopes forever changed the way humans envisioned their cosmos.

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7 Responses

  1. Amazing that fields, particles, forces and who knows what else can come together to create such a fantastic and beautiful universe of people, things and places known and unknown, and so much more we barely comprehend.

  2. First off, thank you for what you are doing in making science knowledge more accessible to more people!
    Jupiter has been a gem up there this year. Every night when I am out imaging it I think about the excitement Galileo must have had seeing Jupiter’s moons for the first time. I get excited every time and I know they are supposed to be there! I agree, get out and look up! Wonders await!

  3. Magnificent picture! The glory of centuries of civilization embracing the glory of the eons. Nothing like the ancient to question the future.

    BTW, there are apps for smart phones that show all the interesting objects out there, from Capella, to Aldebaran and Beltegeuse. I can now spot quickly Andromeda, and Uranus, so I feel much more at home!

  4. Nice post and photo. By a cool coincidence last night while on a honeymoon vacation in Las Vegas I also took a picture quite similar to yours. Mine has the smaller version of the Eiffel Tower on one side and the beautiful Paris Hotel on the other with Jupiter above and to the left (about 45 degrees) of the full moon and both between the two structures. Taken with an iPod touch 5G Jupiter is more bright in my image. I’d like to share here but I don’t know how to do that without posting it somewhere else and then providing a link.

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