A breathtaking reminder of just how gigantic Jupiter really is

If you're looking for a reminder of how impossibly huge Jupiter is, just take a gander at this image from Cassini. That tiny satellite in front is Io...which is almost the same size and relative distance as our own Moon.

Of course, other than their closeness in size - Io and the Moon are the 13th and 14th largest objects in the solar system, with the Moon about 86.8% the volume of the Moon - the two objects aren't all that similar. While the Moon is more or less geologically dead, Io is the most volcanic body in the solar system. What's amazing is that the distance of Io to Jupiter and the Moon to Earth are both roughly 350,000 to 400,000 kilometers. As you can probably remember from the Apollo photographs, Earth doesn't look quite as big as Jupiter from such a distance.

NASA has some more information on this particular image

Gliding past Jupiter at the turn of the millennium, the Cassini spacecraft captured this awe inspiring view of active Io with the largest gas giant as a backdrop, offering a stunning demonstration of the ruling planet's relative size. Although in the above picture Io appears to be located just in front of the swirling Jovian clouds, Io hurtles around its orbit once every 42 hours at a distance of 420,000 kilometers or so from the center of Jupiter. That puts Io nearly 350,000 kilometers above Jupiter's cloud tops, roughly equivalent to the distance between Earth and Moon. The Cassini spacecraft itself was about 10 million kilometers from Jupiter when recording the image.

Cassini, of course, is better known for its photographs of Saturn, which it reached in 2004 after flying by Jupiter around New Year's Eve 2000.

Via NASA.