Astronomers first started talking about a “golden age” of astrophysics and cosmology in the late 1990s. Half a decade later the golden age is still going strong and shows no sign of ending. The past month has seen an impressive list of new results, including the unveiling of the Hubble Ultra Deep Field and the detection of Abell 1835 IR1916 – a galaxy with a record-breaking redshift of 10. Both of these findings tell us about the very early or very distant universe. Closer to home, meanwhile, space scientists have reported the first direct evidence for water on Mars and what might be the 10th planet in the solar system.
And as the results roll in from existing telescopes and spacecraft, a whole new generation of facilities is ready to join the fray. The Rosetta “comet chaser” took off on 2 March, and at least five other missions are planned for launch later this year: Gravity Probe-B will test various predictions of general relativity; Messenger will orbit Mercury; Double Star will study the Earth’s magnetosphere; Swift will analyse the afterglows of gamma-ray bursts; and Deep Impact will set off for comet Tempel 1. Add in various ground- and balloon-based telescopes and instruments, plus the plans for 2005 and beyond, and you have to ask, where will it end?
Of course, it is not all good news. It looks as if there will be no more missions to service the Hubble Space Telescope (HST) following the introduction of new safety procedures at NASA in the wake of the Columbia accident. Disappointing as the eventual demise of Hubble will be, it is not entirely unexpected. As long ago as June 1999 the then NASA administrator Daniel Goldin warned astronomers that “too many of you are hugging Hubble. HST is not your most important optical telescope today”. Even without Hubble, astronomers will have an extraordinary array of instruments at their disposal.
Ironically, the outstanding questions in the golden age concern the dark side of the universe – what are the “dark matter” and the “dark energy” that cannot be seen but which make themselves known through their gravitational influence? These questions cannot be answered by astronomers alone. Astroparticle physicists have been searching for dark-matter particles in underground laboratories with increasing sensitivity for over a decade, albeit without success, and dedicated experiments to learn more about dark energy – the mysterious energy that is thought to account for almost two-thirds of the universe – are just beginning to take shape.
But dark matter and dark energy are just two puzzles, albeit two extremely difficult and important ones, in a galaxy of questions that still have to be answered. How do planets form? What about stars, galaxies, gamma-ray bursts and ultrahigh-energy cosmic rays? And what can astrophysical measurements tell us about quantum gravity? Answering these questions is sure to guarantee that the golden age continues well into the future.
