Astronomers See Spot’s Runt, Clue of Jupiter Climate Change

Times Staff Writer

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

The new spot -- dubbed Red Spot Junior -- 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 last few weeks. NASA released pictures Thursday taken by the Hubble Space Telescope, showing both red spots at a level of detail unmatched since Voyagers 1 and 2 flew past Jupiter a quarter-century ago.

“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 -- Jupiter has no solid surface. As a result, 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. The third merged into a large white oval the size of Earth in 2000.


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

“Something white that lives this long never turns red,” Simon-Miller said. “That’s very unusual.”

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 the sun’s ultraviolet light.

One scientist, Phil Marcus of UC Berkeley, had predicted such a result several years ago as part of a change in the planet’s climate.


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

“If it is climate change it could be periodic, as on Earth,” Simon-Miller said. “It will be really interesting to see.”

The Great Red Spot is rotating westward, while the new red spot is swirling eastward. They are expected to pass each other in July.