That was then, this is now!

Back in the 1960s when I began my interest in astronomy, the best pictures we had of the nine planets were out of focus black and white photos. I am astonished how far we have come since then and decided to devote this blog to a gallery of the best pictures I could find of our solar system neighbors! First, let’s have look at the older photos.

First we have Mercury, which is never very far from pour sun and a very challenging telescopic object.

Above is what mars looked like! Then we have Jupiter and Saturn shown below.

Among the hardest and most mysterious objects were Uranus shown here. I will not show a nearly identical telescopic view of Uranus.

Finally we come to Pluto, which has always been a star-like object for most of the 20th century.

These blurry but intriguing images were the best we could do for most of the 20th century, yet they were enough to encourage generations of children to become astronomers and passionately explore space. The features of mercury were mere blotches of differing shaded of gray. Uranus, Neptune were slightly resolvable to reveal faint details, and distant Pluto remained completely star-like and unresolved, yet we knew it was its own world many thousands of kilometers across. Mars continued to reveal its tantalizing blotchy features that came and went with the seasons along with the ebb and flow of its two polar ice caps. Jupiter was a banded world with its Great Red Spot, but the details of these atmospheric bands was completely hidden in the optical smearing of our own atmosphere. Saturn possessed some large bands, and its majestic ring system could be seen in rough detail but never resolved into its many components. As for the various moons of these distant worlds, they were blurry disks or star-like spots and never revealed their details.

The advent of the Space Program in the 1960s, and the steady investment in spacecraft to ‘fly by’ these planets led to progressively higher and higher resolution images starting with Mariner 4 in 1965 and its historic encounter with Mars, revealing a cratered, moonlike landscape. The Pioneer spacecraft in the early 1970s gave us stunning images of Jupiter, followed by the Voyager spacecraft encounters with the outer planets and their moons. Magellan orbited Venus and with its radar system mapped the surface to show a dynamic and volcanic surface that is permanently hidden beneath impenetrable clouds. Finally in 2015, the New Horizons spacecraft gave us the first clear images of distant Pluto. Meanwhile, many return trips to our own moon have mapped its surface to 2-meter resolution, while the MESSSENGER spacecraft imaged the surface of Mercury and mapped its many extreme geological features. Even water ice has been detected on mercury and the moon to slacken the thirst of future explorers.

For many of the planets, we have extreme close up images too!
Jupiter’s south pole from the Juno spacecraft shows a bewildering field of tremendous hurricanes each almost as large as Earth, swirling about aimlessly in a nearly motionless atmosphere.

Pluto details a few hundred meters across. Can you come up with at least ten questions you would like answers for about what you are seeing?

Here is one of thousands of typical views from the Martian surface. Check out the rocks strewn across the field. Some are dark and pumice-like while others are white and granite-looking. ‘Cats and dogs living together’. What’s going on here?

The Venera 13 image shown below from the surface of Venus is unique and extremely puzzling from a surface that is supposed to be hotter than molten lead.

We also have images from a multitude of moons, asteroids and comets!
The Lunar Reconnaissance Orbiter gave us 2-meter resolution images of the entire lunar surface allowing us to revisit the Apollo landing sites once more:

The dramatic canyons and rubble fields of a comet were brought into extreme focus by the Rosetta mission

Even Saturn’s moon Titan has been explored to reveal its extensive liquid nitrogen tributaries

This bewildering avalanche of detail has utterly transformed how we view these worlds and the kinds of questions we can now explore. If you compare what we knew about Pluto before 2015 when it was little more than a peculiar ‘star in the sky’, to the full-color detailed orb we now see, you can imagine how science progresses by leaps and bounds through the simple technique of merely seeing the object more clearly. It used to be fashionable to speculate about Pluto when all we knew was its size, mass and density and they it had a thin atmosphere. But now we are delightfully challenged to understand this world as the dynamic place that it is with mountains of ice, continent-sized glaciers, and nitrogen snow. And of course, the mere application of improved resolution now lets us explore the entire surface of our moon with the same clarity as an astronaut hovering over its surface from a height of a few dozen feet!

We Old-Timers have had a wonderful run in understanding our solar system as we transitioned from murky details to crystal clarity. All of the easy low-hanging fruit of theory building and testing over the last century has been accomplished for the most-part. Now the ever more challenging work of getting the details straight begins, and will last for another century at least. When you can tele-robotically explore planetary and asteroidal surfaces, or perform on-the-spot microscopic assays of minerals, what incredible new questions will emerge? Is there life below the surface of Europa? Why does Mars belch forth methane gas in the summer? Can the water deposits on the moon be mined? Is Pluto’s moon Charon responsible for the tidal heating of an otherwise inert Pluto?
One can only wonder!

Check back here on Tuesday, April 18 for my next topic!