We have been exploring the solar system for decades, either from the ground or through several emissaries sent there. Over time, technological advancements have obviously allowed us to appreciate the different planets of our system in finer and finer detail. Here is a small overview of this evolution.
NASA’s Mariner 10 mission made several close flybys of Mercury, the first of our system’s planets, from February 1974 to March 1975, revealing craters as small as 150 meters in diameter. The image above, taken on March 29, 1974, was captured when the probe was 5,900 kilometers from the surface.
And here is Mercury photographed by MESSENGER, on site from 2011 to 2015. Unlike Mariner 10, the probe entered orbit around the planet. The image above was taken on October 2, 2013.
On its way to Mercury, Mariner 10 passed by Venus to say hello. In January 1974, the spacecraft captured this ultraviolet view of the most sulfurous of the planets in the solar system, revealing an atmosphere rich in carbon dioxide.
And here is Venus captured by the Japanese Akatsuki probe, stationed in orbit around the planet since 2015. The image above is in false color. Taken on July 11, 2020, it shows us Venus through two ultraviolet channels that reveal the different components of its atmosphere.
Mariner 4 was the first spacecraft to make a close flyby of Mars on July 15, 1965.
Mariner 4 returned a number of images showing clear evidence of craters on Mars. The image above shows us a heavily cratered region located south of Amazonis Planitia.
And here is one of the last pictures of Mars. We owe this shot to NASA’s Mars Reconnaissance Orbiter (MRO) which has been there since 2006. The false color image above shows a lot of wind-related features including ridges, sand dunes and mega-ripples near Gamboa Crater. Now, our views of the Martian surface are almost as good as our space views of Earth, not to mention the photos taken on the ground by the various rovers.
Launched in March 1973, Pioneer 10 was the first probe to visit Jupiter, the largest planet in our system. The image above was taken on December 1, 1974 when the craft was 2.69 million kilometers from the surface.
And here is one of the last portraits of the giant signed by the Juno probe. This extraordinary view is made up of three color-enhanced images. It was taken on February 12, 2019 during its seventeenth flyby.
NASA’s Pioneer 11 probe captured this close-up view of Saturn (and its moon Titan) on August 26, 1979. The craft was 2.84 million km from the surface.
And here is Saturn photographed by the Cassini probe on September 16, 2006. It is one of the most spectacular views of the planet. The panorama was assembled from 165 images captured by the probe’s wide-angle camera over nearly three hours.
We owe this first portrait to the Voyager 2 probe, which flew by the planet in January 1986. The pale blue-green color of the planet’s thin crescent, a product of atmospheric methane, matched the colors captured by ground-based telescopes on Earth. . The probe was about a million miles from the surface where this photo was taken.
Here is our best portrait of the planet, still signed Voyager 2. No probe has indeed visited Uranus since. Encouraging fact: a mission could however join it by 2049.
Voyager 2 also captured this remarkable close-up view of Neptune, the last of the planets in our system, two hours before its closest approach on August 15, 1989. As with Uranus, the planet’s blue coloration comes from the presence of atmospheric methane .
Again, Voyager 2 is the only spacecraft to have flown by Neptune. This image taken on August 25, 1989 is one of the best views we have of the ice giant. The Great Dark Spot is a storm comparable to the Great Red Spot on Jupiter.
And finally Pluto
We end with Pluto, which is no longer officially a planet, but a dwarf planet. On October 4, 1990, the Hubble telescope, then recently launched, allowed us to have a first look at what was still considered a planet at that time.
And here is Pluto photographed in all its glory by the New Horizon spacecraft on July 13, 2015. The spacecraft’s Long Range Reconnaissance Imager (LORRI) captured this shot while it was 768,000 kilometers from the surface.