Earth

Launched on August 3, 2004, the MESSENGER spacecraft's trajectory took it back to Earth for a gravity assist flyby a year later. This image, taken on August 2, 2005 as MESSENGER prepared to depart again for the inner Solar System, shows the western margin of the South American continent (bottom), Mexico (top), and the tropical depression that would develop into Tropical Storm Harvey the next day (far right).

Today's image of Earth serves two purposes. First, it recalls the remarkable journey MESSENGER has undertaken since launch to become the first spacecraft to orbit Mercury. But it also reinforces the concept of comparative planetology that much of what we know of Mercury's geology is rooted in what we have learned from studying our home planet. Whether it be Mercury's large-scale tectonic deformation, its widespread volcanic resurfacing, or even how impacts have shaped its surface, Earth has given scientists a thorough grounding in the tools needed to understand the innermost planet.

Date acquired: August 2, 2005
Image Mission Elapsed Time (MET): 31489858
Image ID: 1063
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
Center Latitude: -0.4°
Center Longitude: 269.8° E
Resolution: 7.6 kilometers/pixel
Scale: The field of view in this image covers approx. 64° of arc (7,137 km or 4,436 mi.) across Earth's surface
Incidence Angle: 22.5°
Emission Angle: 33.6°
Phase Angle: 55.5°
The north pole is to the top right in this image.

Photo credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington