Today’s physics news: What they didn’t tell you about the transit of Venus and more

Today’s physics news: What they didn’t tell you about the transit of Venus, nations at odd on Rio +20 and more

What they didn’t tell you about the transit of Venus
Despite an avalanche of media coverage, few mentioned the main historical reason for measuring transits of Venus
Guardian

Nations at odds on Rio+20 earth summit
The final round of negotiations leading up to next week’s Rio+20 summit begins on Wednesday with countries very much at odds on key issues
BBC

Small, cheap black-hole hunter could be new NASA model
The NuSTAR space telescope’s images will be 10 times as crisp as those of any previous telescope
New Scientist