Earlier, we had an article about how our advancing capability to observe the universe would soon enable the detection of Earth-like planets in distant star systems. Today, I present a complementary article, in which we will examine the progression in telescopic power, why the rate of improvement is so much faster than it was just a few decades ago, and why amazing astronomical discoveries will be made much sooner than the public is prepared for.
The first telescope used for astronomical purposes was built by Galileo Galilei in 1609, after which he discovered the 4 large moons of Jupiter. The rings of Saturn were discovered by Christaan Huygens in 1655, with a telescope more powerful than Galileo's. Consider that the planet Uranus was not detected until 1781, and similar-sized Neptune was not until 1846. Pluto was not observed until 1930. That these discoveries were decades apart indicates what the rate of progress was in the 17th, 18th, 19th, and early 20th centuries.
The first extrasolar planet was not detected until 1995, but since then, hundreds more with varying characteristics have been found. In fact, some of the extrasolar planets detected are even the same size as Neptune. So while an object of Neptune's size in our own solar system (4 light-hours away) could remain undetected from Earth until 1846, we are now finding comparable bodies in star systems 100 light years away. This wonderful, if slightly outdated chart provides details of extrasolar planet discoveries.
The same goes for observing stars themselves. Many would be surprised to know that humanity had never observed a star (other than the sun) as a disc rather than a mere point of light, until the Hubble Space Telescope imaged Betelgeuse in the mid 1990s. Since then, several other stars have been resolved into discs, with details of their surfaces now apparent.
So is there a way to string these historical examples into a trend that projects the future of what telescopes will be able to observe? The extrasolar planet chart above seems to suggest that in some cases, the next 5 years will have a 10x improvement in this particular capacity - a rate comparable to Moore's Law. But is this just a coincidence or is there some genuine influence exerted on modern telescopes by the Impact of Computing?
Many advanced telescopes, both orbital and ground-based, are in the works as we speak. Among them are the Kepler Space Observatory, the James Webb Space Telescope, and the Giant Magellan Telescope, which all will greatly exceed the power of current instruments. Slightly further in the future is the Overwhelmingly Large Telescope (OWL). The OWL will have the ability to see celestial objects that are 1000 times as dim as what the Hubble Space Telescope (HST) can observe, and 5 trillion times as faint as what the naked eye can see. The HST launched in 1990, and the OWL is destined for completion around 2020 (for the moment, we shall ignore the fact that the OWL actually costs less than the HST). This improvement factor of 1000 over 30 years can be crudely annualized into a 26% compound growth rate. This is much slower than the rate suggested in the extrasolar planet chart, however, indicating that the rate of improvement in one aspect of astronomical observation does not automatically scale to others. Still, approximately 26% a year is hugely faster than progress was when it took 65 years after the discovery of Uranus to find Neptune, a body with half the brightness. 65 years for a doubling is a little over 1% a year improvement between 1781 and 1846. We have gone from having one major discovery per century to having multiple new discoveries per decade - that is quite an accelerating curve.
We can thus predict with considerable confidence that the first Earth-like planet will make headlines in 2010 or 2011, and by 2023, we will have discovered thousands of such planets. This means that by 2025, a very important question will receive considerable fuel on at least one side of the debate...