Old galaxies, new problems
The expansion of the universe means that the light from distant galaxies is red-shifted when observed on Earth. The larger the red shift, the greater the distance to the galaxy. Moreover, when we view...
Sandage and Peebles win cosmology prize
Sandage is best known for his efforts to pin down the values of the Hubble constant, the age of the Universe and its deceleration parameter through observations. Peebles is a theoretical cosmologist w...
Read article: Boomerang backs flat universe
Boomerang backs flat universe
The geometry of the universe is Euclidean and space is flat. This has now been confirmed from detailed measurements of the cosmic microwave background – the radiation left over from the big bang...
Read article: The universe is flat – official
The universe is flat – official
All the matter and radiation in the universe was created by the big bang. The radiation stopped interacting with the matter about 300,000 years later – when the universe had cooled down enough f...
The hard X-ray background comes into view
The CXB covers a range of photon energies, with a peak around 40 kiloelectron volts (keV). The soft X-ray part of the background – photon energies between about 0.5 and 2 keV – was extensi...
Astronomy and physics dominate Science top ten
Confirmation that the universe is flat – expanding at just the right rate not to collapse – came from measurements of ripples in the cosmic background radiation left over from the big bang...
Read article: Astrophysics and cosmology: the golden age
Astrophysics and cosmology: the golden age
Our understanding of the universe has advanced immeasurably in the last century, and there seems no end to the wealth of new discoveries as we approach the next millennium
Clouds puzzles astronomers
Astronomers have argued about high-velocity clouds for over thirty-five years. Wakker and colleagues detected ionized sulphur in one such cloud using the Hubble Space Telescope. According to their cal...
More evidence for the accelerating universe
The first evidence for the accelerating universe came from observations of distant supernovae. However, the data were also consistent with an open universe – a universe that would expand forever...
Gas cloud defines extragalactic distance
The team were able to measure the distance because NGC4258 is one of 22 nearby galaxies that have active nuclei consisting of a supermassive black hole (over 100 million solar masses) surrounded by a ...
