Real images of the Solar system: how they changed changed before and after the digital
revolution.
Episode 1, from the Sun to Mars
In the span of a single lifetime, a momentous transformation in human consciousness has
quietly taken hold: We are beginning to think of our home not as the Earth but as the Solar
System.
Thanks to the photographic output of a small squadron of interplanetary spacecraft, a picture
of the visual splendor and variety of the Solar System is emerging.
Since then, probes built with more powerful cameras and greater maneuverability have looked
deeper into the turbulent clouds and wheeling satellites of Jupiter; roamed the boulder-strewn
red deserts of Mars; studied Saturn's immaculate rings; and chronicled vast upheavals erupting
from the Sun itself.
Before modern telescopes, humans could only imagine what the surface of the sun and the
planets looked like.
Now advanced technology has made it possible to get in close, and take images of the Sun
and the planets deep in our solar system.
If you guys have the patience to follow us for about ten minutes we will show you the
profound difference between the planetary images of a few years ago, definitely "ugly"
and those that delight our eyes today!
OK guys, I admit it... by now I have reached an age that allows me to compare, for having
personally lived it, the pre-Apollo and pre-digital era with the one we are living in this moment
in the field of space exploration and scientific imaging.
This means that I was a kid when in school books, photos of planets were just fuzzy black
and white blobs.
But one can go back even further...
There was indeed a time when planets, apart from the Sun and Moon, could only be perceived
by us earthlings as more or less bright points of light.
This period lasted from when the first representative of our species raised his eyes to the sky
wondering for the first time what were all those lights that lit up after the sunset,
until the invention of the telescope, in 1609.
The next period is from the invention of the telescope until the early sixties of the last
century.
Approximately three centuries and a half, during which astronomers have first tried
to draw the scarce (and often illusory) details that they could discern on planetary disks
devastated by atmospheric turbulence, and then pass, at the beginning of the twentieth
century, to the first timid attempts of photographic shooting.
With mostly disappointing results, always due to turbulence even more exacerbated by
the fact that the poor sensitivity of the films of the time forced astronomers to very
long poses even with bright subjects such as planets.
And the longer a pose is, the more turbulence cancels contrasts and erases details.
In short, we can certainly say that until the sixties the planetary photos taken from
Earth (even those of the great observatories like Palomar and Mount Wilson), judged with
the eyes of the present, could be defined as very disappointing.
This state of affairs lasted until the first interplanetary probes, equipped not with film...
but with cathode-ray tubes, entered the field.
The Mariner 4, for example, in 1965 sent home the first close-up photos of the Martian surface,
in black and white and with a resolution (today ridiculous) of 210 lines by 210 columns.
Sufficient, however, to destroy forever the theory of channels and to show us a world
very different from what we had imagined.
Mars appeared in fact studded with craters, almost like the Moon.
It did not have a magnetic field worthy of note (and therefore was exposed from solar
radiation) and the atmosphere was cold and thin.
No evidence of alien civilizations, of course, nor any hope of easy exploration.
But the image we had of the solar system began to change totally only in 1976 with the Viking
probes that landed on Mars, and then with the Pioneer and Voyager in the eighties.
It was then, in fact, that the old dimensionless points of light, and the ugly blurry photographs
of the turn of the century, suddenly became shapes, colors, and phenomena in flux.
No longer faded postcards, but worlds and moons with mountains, volcanoes and ice.
In the years that followed all the planets of the solar system were visited and photographed
by automatic probes, but also the imaging from the ground, assisted by CCD sensors increasingly
large and sensitive made giant processes, giving us enchanting views of the planets
closer and more telegenic.
And not only by professional astronomers and large observatories, but also by astrophotographers
equipped with absolutely amateur instruments.
This was the real great revolution: digital sensors within everyone's reach!
Not only... but the great increase in image quality also depended on another factor.
In the past, images of the solar system were acquired by capturing a single image through
a simple eyepiece projection adapter (an accessory that allowed a medium to high power eyepiece
to be placed between the telescope and camera body) attached to the focuser of a telescope.
It has largely been replaced by a process that is known as "Lucky Imaging".
This method allows for the capture of hundreds to thousands of individual frames taken with
a high-speed video camera in a very short amount of time, and then stacking the best
of those frames to form a final image that can be further enhanced with sharpening techniques.
But it is time to bring some evidence for what we are saying.
For example, look at these photographs of the Sun taken by the Mount Wilson Observatory
in 1946 and the National Astronomical Observatory of Japan in 1984...
At the time they were as good as it gets.
And then compare them with the extraordinary color images below...
Amazing the difference, isn't it?
All thanks to telescopes designed for the specific observation of the Sun, such as the
Gregor Telescope of the Canary Islands, to which we owe the beautiful animation that
shows the evolution in 20 minutes of a sunspot of 20,000 km in diameter.
And above all, thanks to the very high resolution digital sensors and the latest generation
of adaptive optics systems.
And what about the photographic shots of the amateur astronomer Alan Friedman, who in recent
years has literally changed the standard of solar imaging with its special processing?
Color, light... here the astronomical object is shown as a work of art exhibited in the
case of a museum!
Let's not talk about probes such as the Solar Dynamics Observatory, which for many years
now, minute by minute, has been monitoring the Sun in all its aspects and at all wavelengths,
giving us incredible views of what in its movies appears for what it is: a real "atomic
furnace".
Frightening images…
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But let's proceed with order, and from the brightest and most obvious object of the solar
system, we pass to one of the most hidden, so much so that even Copernicus admitted he
had never been able to see it: Mercury!
The small planet, since it is the closest to the Sun, seen from Earth often appears
in the glow of morning or evening twilight, and until the era of probes on its brilliant
surface had never been reported any detail.
Even with the best telescopes and in the best photographs all you could get was an indistinct
smudge of light in the form of a sickle...With the digital era things have improved, but
only the probes, from Mariner 10 in 1974 to Messenger in 2008-2015, were then able to
reveal the appearance of its surface, which as you can see in the film made by Messenger,
appears cratered like the lunar one.
In the photographic realm, Venus' story is also somewhat similar to that of Mercury.
Despite Venus being more "convenient" to observe and much larger and closer to Earth, its perennial
cloud cover has always prevented us from photographing its surface; with the glorious exception of
the extraordinary photos taken by the Soviet Venera series probes that landed on the planet
from 1970 onwards.
And in this regard, do you want to know something?
It is not at all true that Perseverance was the first probe to capture the wind noise
on an alien planet.
The first one to do so was Venera 13 itself, in 1982!
And you can hear it very well in the film that we propose
However, it was Magellan who put things right with the topography of Venus.
In the early nineties, the NASA probe realized in fact the entire mapping of the Venusian
surface using radar shots capable of piercing the thick layer of clouds.
So much that by now we can say to have an excellent knowledge of the geological structure
of this mysterious planet.
And after Venus?
Well, proceeding towards the outside of the solar system it is impossible not to stop
and contemplate for a moment that oasis full of life that is our planet: the "pale blue
dot", as Sagan defined it...
And to underline, also in this case, the enormous improvement in the images, we will show you
two very similar shots: the first photographic portrait of our planet, taken on August 23,
1966, by Lunar Orbiter I, and the one taken by the Apollo 8 crew only 28 months later,
in December 1968...
It's an incredible difference, don't you think?
As well as incredible, years later, will be the shots of the Earth-Moon system made by
the Lunar Reconnaissance Orbiter ...
And we have already arrived at Mars: the alter ego par excellence of our planet, and therefore
observed, designed and photographed by generations of astronomers.
A definitely photogenic planet, at least during its maximum approaches, which are repeated
every 15-17 years.
Until the fifties, however, the photos were so confusing to make believe that it could
host at least plant life.
There were in fact no traces of craters, and nothing made to think it could be an arid
world.
All this, we have already said, until in 1965 Mars was not visited by the probe Mariner
4.
Then the Viking in 1976 gave us the first landscapes, so similar to those of our desert
regions, while the advent of digital produced images of the red planet increasingly detailed
even among those taken by terrestrial telescopes.
The Hubble Space Telescope has often participated in this competition of ability, with global
images of Mars full of details.
Nowadays, with the many probes that still turn around, we can say we know the Martian
topography even greater than that of the Moon ... especially thanks to the extraordinary
capabilities of the Mars Reconnaissance Orbiter, operational since 2006.
The film that we show you is worth more than a hundred words.
And after Mars?
After Mars, the asteroids...
But this will be a goal that we will reach in the next video appointment, when we will
discover the best images of asteroids and comets, and then of Jupiter, Saturn, Uranus,
Neptune and Pluto.
And also for each of these objects, we will show you a "before" and an "after", testifying
the enormous progress made by astronomical imaging in recent years.
See you soon!