How can this be? There aren't any human beings there.

From the Seattle Times:

Jupiter's Great Red Spot suddenly has a sibling, an enormous new spot that some planetary scientists think could be evidence of climate change sweeping the gaseous planet.

The new spot is roughly half the size of the Great Red Spot. Both are caused by violent storms churning the upper atmosphere of the solar system's largest planet.

Amateur and professional astronomers have been observing the new spot for the past few weeks. The National Aeronautics and Space Administration on Thursday released pictures taken by the Hubble Space Telescope, showing both red spots.

"Planets with atmospheres are dynamic and changing," said Ray Villard of the Space Telescope Science Institute in Baltimore. "So it's nice to have Hubble out there to record these atmospheric changes over time."

As on the other planets known as gas giants — Saturn, Uranus and Neptune — there is no solid surface below the red spots on Jupiter. As a result, the storms can be long-lasting, constantly replenishing themselves from below.

The Great Red Spot dates at least to the 17th century, when the first telescopes revealed it to observers on Earth. It is large enough to contain two or three planets the size of Earth. The storm rises as high as five miles above the surrounding cloud level.

The new red spot began as three white ovals, which are cooler, upper-level storms, according to Amy Simon-Miller of NASA's Goddard Space Flight Center in Greenbelt, Md. One of the three was first spotted in 1939; the other two date to 1915.

In 1998, two of them merged, and in 2000 the third joined them to form a large white oval the size of Earth.

"Last year, some amateur astronomers reported the white oval was getting brownish," Simon-Miller said. Then early this year, it turned red, shocking professional astronomers.

"That's very unusual," Simon-Miller said.

Some astronomers believe the most likely explanation for the color change is that the storm is dredging up material from deep in Jupiter's atmosphere, which turns red after reacting chemically with ultraviolet light from the sun.

Observing climate change on another planet would be a major scientific event, astronomers said. They cautioned that it's too soon to know if it is occurring on Jupiter, or whether it can tell scientists anything about climate change on Earth.

Maybe it was those Voyager probes that somehow contaminated the Jovian atmosphere with anthropogenic emissions. I mean, a planet's atmosphere can't change naturally, can it?