It's a warm, clear Summer night in Melbourne tonight and gazing out from the window, I can see stars! Brightest object in the sky is the planet Jupiter, seen in the first photo, with nearby star Wasat (Delta Geminorum).
I zoomed in with my camera (a compact Sony DSC-HX90V) and with a bit of fiddling I was able to capture the second photo, showing Jupiter and its four Galilean moons, and Wasat.
The last image is a screen capture from the excellent, free, planetarium program "Stellarium". It shows in greater detail what I was observing through the camera. Isn't technology wonderful?
The Galilean moons are the four largest moons of Jupiter. They are, in descending-size order, Ganymede, Callisto, Io, and Europa. They are the most readily visible Solar System objects after Saturn, the dimmest of the classical planets; though their closeness to bright Jupiter makes naked-eye observation very difficult, they are readily seen with common binoculars, even under night sky conditions of high light pollution.
The invention of the telescope allowed astronomers to discover the moons in 1610. Through this, they became the first Solar System objects discovered since humans have started tracking the classical planets, and the first objects to be found to orbit any planet beyond Earth.
They are planetary-mass moons and among the largest objects in the Solar System. All four, along with Titan, Triton, and Earth's Moon, are larger than any of the Solar System's dwarf planets. The largest, Ganymede, is the largest moon in the Solar System and surpasses the planet Mercury in size (though not mass).
This post is part of the Skywatch Friday meme.
