More than 50 years of planetary exploration have yielded a rich harvest of data, including many volumes of pictures. These images have revealed the faces of nearly all the nearby worlds, which have turned out to be both forboding and inviting, alien and familiar. Everywhere there is beauty.
We have enough images, in fact, that for many planets, moons, and small bodies we can construct full, global maps. This has been true for places like Mars for decades. For others, such as Mercury and the asteroid Vesta, it has become possible only in the past few years, thanks to the ongoing work of robotic scouts throughout the Solar System and the dedicated people on Earth who fly them.
Following is a series of short videos showing the worlds of the inner Solar System spinning to show their various faces. With two exceptions, each video resulted from taking thousands of individual observations from spacecraft, and combining the data into a 3D computer model.
This look at the Sun comes from the Solar Dynamics Observatory in orbit around the Earth. It shows the Sun as it appeared over the course of the past few days, as seen by sensors tuned to three different wavelengths of extreme ultraviolet light. Later in the decade, new missions will actually fly close to the Sun for even more detailed shots.
Rotating Sun in Three Wavelengths The sun as it appeared over the course of two days in February, 2014, as seen by the Earth-orbiting Solar Dynamics Observatory in three different extreme ultraviolet wavelengths. NASA/GSFC/SDO/AIA
This globe comes from thousands of obesrvations by the MESSENGER spacecraft in orbit around Mercury. MESSENGER carries cameras that can observe many wavelenths of light as it bounces off the planet, in order to spy different minerals on the surface. This map shows greatly exaggerated colors in order to highlight the diversity of geology.
Rotating Mercury Map An enhanced-color global map of Mercury's surface created from thousands of sets of images obtained by the MESSENGER spacecraft. The colors shown here are related to variations in the spectral reflectance across the planet. NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
Venus is entirely shrouded in dense clouds, of course, but in the 1990s the Magellan spacecraft mapped the surface anyway using radar. The video highlights two large "continents," or highlands, Aphrodite Terra and Ishtar Terra, the Maxwell Montes mountain range, and Maat Mons, a large, currently dormant volcano. Notice the motion of the clouds at the beginning. Venus is the one inner planet that rotates "backwards" to the other planets.
Rotating Venus Map This animation is a brief tour of the global terrain of the planet Venus as revealed by radar onboard the Magellan spacecraft. The height of the terrain is color-coded, with blues and greens representing low altitudes and reds representing high altitudes. NASA/GSFC Scientific Visualization Studio
This map of the moon comes from thousands of photos sent by the Lunar Reconnaissance Orbiter. Each was taken when the Sun was nearly directly overhead at the moment the image was taken. When all stitched together, they make a globe of striking crispness and clarity.
Rotating Moon Map A rotating mosaic of the Moon based on extensive data from the Lunar Reconnaissance Orbiter. NASA/GSFC/ASU
Here is Mars, showing both the actual relief of its surface features, and a version where the topographical data has been wildly stretched to draw out the planet's complex landscapes.
Mars Globe Rotation with Crazy Topography Two full rotations of a Mars globe using Viking imagery and MGS-MOLA topography. First rotation, about normal topographic height - then it turns up to massively exaggerated topography. Rendered at 1920 in 3DS Max 2009 with Vray. Created by Doug Ellison. NASA / Doug Ellison
Finally, we have Vesta, a tiny place compared to these other worlds, but a giant among the members of the asteroid belt. This rotation is not a computer model, but a series of images stitched together from photos sent by the Dawn spacecraft.
Vesta rotation movie (smoothed, high-resolution) Dawn captured 64 images of Vesta over one rotation period (a little more than 5 hours) from a distance of 5,200 kilometers on July 24, 2011, making a movie of its rotation. In this 720p native resolution version, Tayfun Öner has tweened the images, making the rotation appear smoother. NASA / JPL-Caltech / UCLA / MPS / DLR / IDA / smoothed by Tayfun Öner
These spinning globes show how much we've explored. On the other hand, they serve as a reminder of how much remains unseen. There is no rotating map of the largest asteroid Ceres, or of Pluto. That situation will change next year. However, there are many other worlds in the outer Solar System where there are still blank spaces on the map. Sadly, there are no missions even on the drawing board to explore most of them.
There is still much to do.