But while it has been a success story, its biggest contribution was the finding of infrared light, so important to all stars and other galaxies.
In 1989, the Keck telescope, right behind Spitzer in the telescope’s field of view, revealed the faintest and longest, most distant image it obtained of distant regions of the night sky: the Great Andromeda galaxy. This was the first image of our home galaxy taken by a telescope this distant (the entire visible sky, for that matter, is so far).
Since then we have obtained an astonishing 1.33 billion photographs of the Milky Way, and this last month we received the most detailed view of the universe’s invisible glow ever created from a telescope, a billion-degree view of the universe (with only the Hubble Space Telescope the equivalent of a billion light years away).
But why, then, does the Hubble Space Telescope focus on distant galaxies, rather than those that surround us? Because these are the first galaxies to appear; we have seen no other forms of matter or life on worlds distant from Earth. And those that do exist are so far from us that no telescope for observation has been built to look beyond 5 or 6 degrees.
Now we know that the galaxies farthest from us are as massive as the Sun (and far more so than the Milky Way), and that planets beyond our solar system exist in galaxies about 100 times farther away. Those that aren’t are so huge that they cannot be seen. But does that make the entire Universe invisible, as some (but not all) scientists assert? Actually, no. On the contrary, in principle, it may mean that there is nothing visible at all! This is the basic idea behind the concept of dark energy, also called the “cosmic vacuum.” The principle is that the space beyond ordinary space is more empty, and that there is some other space, a “dark energy layer.”
Thus, rather than using any form of direct observation to expand the Universe beyond its current bounds, our telescopes are being used to see what is there from all directions. In all the light we have sent back since the time of Spitzer, only a tiny fraction has been absorbed. This dark energy is invisible to all of us, and in that respect it is true that we are observing a microscopic universe (of only one trillionth the width of a human hair), but there are thousands of billions of galaxies out there.
Now the most important feature of all these observations is the discovery of very strong signals in the microwave portion of the electromagnetic spectrum, showing clearly for the first time that the Universe contains a powerful mechanism for making gravity itself. The theory and technology that produced these signals, known as the “Cosmic Microwave Background,” means that we can now use our instruments to look inside a million and a half million years ago when the cosmos was less than 10 percent more than it is now.
We can look so far into the past, for so much more time, and observe such an immense and complex cosmic web of galaxies, that we can’t even begin to estimate what it might have been like to live in the very early stages of the Universe. And so the image produced by the Spitzer infrared data is no longer merely an unending line of galaxies beyond a billion light years away. It is a snapshot of what might have been, a hint of what may yet be!
And while there is no evidence for an earlier “Cosmic Big Bang,” many scholars have proposed alternatives that do. Such as the theory of inflation, which predicts that huge expanses of empty space may have expanded in the Universe in a recent period of time. They would then have been pushed apart – a theory known as “Dark Matter.” While nothing is quite proven, it is interesting to note that the earliest stars are very far away, and that the earliest galaxies are not yet seen.