Geophysicists at the University of Rochester announce in today’s issue of Nature that the Earth’s magnetic field was nearly as strong 3.2 billion years ago as it is today.

The findings, which are contrary to previous studies, suggest that even in its earliest stages the Earth was already well protected from the solar wind, which can strip away a planet’s atmosphere and bathe its surface in lethal radiation.

The maximum extent of Arctic sea ice in winter 2007 was the second lowest on satellite record, narrowly missing the 2006 record, according to a team of University of Colorado at Boulder researchers.

The Arctic sea-ice extent, which is the area of ocean covered by at least 15 percent ice, was 5.7 million square miles in March 2007, slightly higher than the record low of 5.6 million square miles measured in March 2006.

Dr Alwyn Ruddock, a former reader in history at the University of London, was the world expert on John Cabot's discovery voyages from Bristol to North America (1496-98). What she was said to have found out about these voyages looked set to re-write the history of the European discovery of America. Yet, when Dr Ruddock died in December 2005, having spent four decades researching this topic, she ordered the destruction of all her research.

In an article published today in Historical Research, Alwyn Ruddock's extraordinary claims are explored by Dr Evan Jones of the University of Bristol.

Mating strategies are straightforward in bottlenose dolphins, or are they? Much of the work carried on male-female relationships in that species to date show that males tend to coerce females who are left with little choice about with whom to mate. This explains the complex relationships we observe in male bottlenose dolphins, which are only paralleled by human social strategies: the formation of alliances and alliances of alliances, also called coalitions. These alliances and coalitions are then used to out-compete other male bands to access females.

NGC 1672, visible from the Southern Hemisphere, is seen almost face on and shows regions of intense star formation. The greatest concentrations of star formation are found in the so-called starburst regions near the ends of the galaxy's strong galactic bar. NGC 1672 is a prototypical barred spiral galaxy and differs from normal spiral galaxies in that the spiral arms do not twist all the way into the centre. Instead, they are attached to the two ends of a straight bar of stars enclosing the nucleus.

HIV-positive people who say religion is an important part of their lives are likely to have fewer sexual partners and engage in high-risk sexual behavior less frequently than other people with the virus that causes AIDS, according to a study issued today by the RAND Corporation.

As a result, people with HIV who have stronger religious ties are less likely to spread the virus, according to the study by the nonprofit research organization.