What do you see astronomy being like in the 21st century?

1. I see astronomy completing its survey of the diverse contents of the visible universe, and our inventory of how the universe has changed since the Big Bang. We will have a definitive inventory that shows all the ways that gravity can shape matter on stellar and galactic scales. There will be no significantly new 'undiscoverable' categories of stars or galaxies. The 20th century was unique in having developed most of such a listing, but you can only do this once per universe!
2. We will extend our mapping of the structure of the universe, galaxy by galaxy, out to 1 billion light years, in detail, and beyond 1 billion light years for some small parts of the sky. From this, we will conclusively establish whether the universe is open or closed with Omega = 1 or Omega < 1. The structure of the universe at greater distances will be a constantly expanding horizon, and we will end this cataloging and redshift surveying when we almost literally run out of galaxies that can be seen. It will be harder and harder to get grant money to continue such a survey because we must eventually run out of questions worth the money and manpower.
3. We will establish what 'dark matter' is, and just how much of it there is in the universe. We will determine the nature of the galactic 'dark matter' component which is widely thought to be under-luminous or non-luminous matter perhaps in black holes, dwarf stars, Jupiters, and the like. This type of dark matter will explain the dynamics of individual galaxies and their constituent stars, but may NOT explain the large scale motions of galaxies inside clusters, or clusters in the larger universe. This second type of dark matter will be quantified by X-ray satellites and the like. And we will know by the end of the first half of the 21st century, just how much of this kind of dark matter is present, and whether it is even matter at all.
4. No mystery can remain so for very long. Even now, the mystery of the infamous 'gamma ray bursts' is buckling as astronomers have captured the fading glow of one of these events, and found that it coincides with a faint, distant galaxy...as many people have expected they would for over a decade. many more of these events will be tracked down, and in the 21st century, we will see the advent of new satellites to study the physics of these events, obtain the ever important spectra of their matter, and so on. This has been the history of every 'mystery' astronomers have uncovered from quasars to pulsars to black holes.
5. The study of extra-solar planetary systems will explode as new instruments supported by NASA's Origins program come on line. By the end of the first half of the 21st century, we will have catalogs of HUNDREDS of these worlds, and have a complete inventory of the planetary systems within a 50 light years of the Sun. We will discover just how typical or a-typical our solar system really is, and what the consequences this has for life on other worlds. We will also have spectral data on many of these worlds, and even a few small enough to be Earth-like twins.
6. We will have an active program of reconoitering Titan and Europa, with crust-penetrating probes to search for ecological niches and conditions where bacteria may have established a toe-hold. We will have sample return missions to many of these spots either enroute or on the drawing boards.
7. We will discover how to stop the deterioration of human bones and health in long-duration missions, and with newer generations of heavy-lift rockets we will again start to reach out and set foot on the Moon and Mars, beginning again where we left off in the 1970's. Most mission profiles are all or nothing. You do not spend 400 days round trip to Mars, just to spend 3 days on the surface like we did with the Moon. We will HAVE to send in advance, lots of resources that will take up parking orbits around Mars, and which will wait there for a crew of astronauts to assemble them and set up a colony on Mars. The colony will STAY there for several years before returning at the next Mars-Earth opposition when relief crews will arrive. This will happen in the 21st century, unless there is a world-wide referendum to abandon space.
8. The commercialization of near-earth space will explode as it is starting to already. Every nation that now has two dimes to rub together is developing a satellite, or a launch vehicle system. Commercial communication satellites will be augmented by 'getaway specials' for people to take $50,000 rides into Earth orbit for one day visits.
9. Gravity wave astronomy will finally come of age as the new, non- electromagnetic, frontier in observational astronomy. Detectors will monitor the collapse of matter into black holes and neutron stars anywhere within 100 million light years of the Milky Way or even beyond as their sensitivities increase. We are still at the Galileo-stage of building sensitive gravity wave detectors. In the next century, these instruments will allow cosmologists to examine what went on in the universe at times far earlier than what the COBE satellite has let us ( 300,000 years after the Big Bang). We will begin to explore conditions before the first SECOND after the Big Bang with these instruments
10. Neutrino astronomy, which has expanded enormously in the last 10 years, will become a major new frontier as more sensitive detectors are built. The contents of the neutrino universe will be imaged and although no new physics is expected, we can never know for sure as we explore this second non- electromagnetic energy spectrum
11. A career in astronomy will still be hard to get as population pressure continues to make more humans available every year. But since the number of 'Einsteins' in humanity seems to be a fixed per capita phenomenon, we will have many more brilliant 'Einstein-caliber' people entering the physics and astronomy professions, which will take these fields in directions we cannot now imagine.
12. New technologies will become available, and amateur astronomers will reap a whirlwind of amazing over the counter equipment which will dwarf the technologies now available to professional astronomers. Amateur astronomers in the 21st century will aggressively colonize the radio frontier and radio telescopes will be come as common to amateurs as optical telescopes were in the 1930's. With 1000 amateur radio astronomers combing the skies for adventure, who knows what odd transient events they will uncover. Even optical interferometers may be attempted by amateur astronomers.
13. Professional astronomers will no longer have research published in paper form, but will use all-electronic media such as the Internet or its 21st century equivalent. This means that historians 200 years from now will only have electronic forms of research papers to work from and no back-up paper copies. This could be a problem if you worry about how permanent electronic data storage will be for 50 - 200 year life times. Already, VHS tapes of family movies degrade badly after 10 - 15 years. The best CDROMS last only 50 - 100 years before the media itself begins to break down. More importantly, the software and platforms needed to retrieve the information change every 5 years. Historians of post-20th century science will have their hands full.
14. Astronomy as a profession will also begin to wane as we run out of new epical questions to ask and answer. We live in a finite visible universe, with only a finite number of interesting 'first' questions' of the first rank. There will be zillions of questions of the second rank, but you can only answer some questions like 'Is the universe going to collapse, or will it expand for ever?' or 'Is our solar system alone?'. After that, you ar in the realm of 'Why does the brightness of the star SAO 190456 vary exactly the way it does?'. Many astronomers will still like to answer those kinds of questions.
15. Last year, physicists confirmed that the quantum mechanical vacuum state is not empty, but produces a repulsive force between conducting plates less than 0.5 microns apart as predicted by Casimir in the 1940's and by Quantum Electrodynamics. This force will be harnessed by 'cheating' Heisenberg's Uncertainty Principle, one electron at a time. With this as a local power source, computers in the next century which use 'quantum processors' now being developed, will no longer require outside power sources to drive them. The first applications will be novelty toys that draw energy out of 'empty space' rather than solar energy. Eventually, larger systems will be designed. We may never be permitted by nature to do more than give single electrons a minuscule 'kick', but a million of these kicks on a single chip might be able to do some useful work for nano-technology.
16. A larger number of astronomers will turn to reflective writing aimed at popularizing or 'integrating in simple terms' the body of astronomical knowledge. The 21st century will be the century of science popularization as governments and citizens ask for more pay-back for their investments in astronomy, and as many astronomers who have become increasingly restless with pure research, begin to find increasing enjoyment in telling others about their work.
17. Because of the inevitable increase in the raw intelligence and curiosity of the average citizen, which has increased steadily for centuries, we will see greater demands places on the entertainment media for thoughtful stories about science in the genre of science fiction.
18. Although some astronomical research may take place on the lunar surface and beyond, the major resources of astronomers for scientific discovery will still come from Earth-orbiting satellite observatories, or ground-based systems. The number of small optical telescopes below 4-meters in size will severely shrink as it becomes cheaper to build large 10-20 meter class instruments. Most active research will be done in Chile and Hawaii, with virtually all North American optical research observatories being forced to close down for lack of 'interesting projects' worth the cost of keeping the observatory active. The exceptions will be optical observatories using optical interferometers.