Jupiter's moons
FASCINATING PHENOMENA OF JUPITER'S MOONS: On Jan. 5th, Earth passed directly between the sun and Jupiter. Astronomers call this an "opposition" because the sun and Jupiter were on opposite sides of the sky. "Jupiter's opposition is always an opportunity for beautiful pictures of moons transiting Jupiter, sometimes directly in front of their own shadows," says John H. Rogers, Jupiter Section Director of the British Astronomical Association. "Observers have produced some fine examples from the opposition earlier this month." Some of the best are collected here:
?PHPSESSID=9cipfrtgahljtp5brasraduc11
If you go to Spaceweather you can embiggen that graphic for a closer look.
Transits around opposition are beautiful, but something even more rare and special is coming this fall. "In autumn, Jupiter's moons will begin a series of mutual eclipses and occultations," Rogers says. The satellites will criss-cross in the sky, dipping in and out of one another's shadows. Predictions by Jean Meeus have been posted by the British Astronomical Association Computing Section atthese URLs.