Spots aren't the sole province of Jupiter. Pluto is also spotty, according to images taken by NASA's New Horizon probe, as it draws ever closer to its July 14 fly-by.
The spacecraft has sent back colour images of the dwarf planet -- revealing two distinctly different hemispheres, one of which has a series of evenly sized, evenly spaced dark spots along the equator.
The images, released Wednesday, weren't sent back as you see them above. Instead, high-resolution black and white data from New Horizons' Long-Range Reconnaissance Imager (LORRI) was combined with lower resolution colour data from its Ralph digital imager.
The uniformity of the spots has the New Horizons research team intrigued.
"It's a real puzzle -- we don't know what the spots are, and we can't wait to find out," New Horizons principal investigator Alan Stern of the Southwest Research Institute in Boulder, Colo., said in a statement.
"Also puzzling is the longstanding and dramatic difference in the colours and appearance of Pluto compared to its darker and grayer moon Charon."
The combined data from the two instruments reveals Pluto and its moon Charon in approximate true colour.
As New Horizons approaches the planet, the team is starting to look for more detailed features. For example, LORRI and Ralph will be able to detect clouds -- if there are any -- during the craft's approach and departure from the planet. This information will reveal further details about Pluto.
"We're looking for clouds in our images using a number of techniques," said Kelsi Singer, a post-doctoral researcher at the Southwest Research Institute. "If we find clouds, their presence will allow us to track the speeds and directions of Pluto's winds."