NASA Science Briefing: Comet Siding Spring at Mars

Extensive systems of fossilised riverbeds have been discovered on an ancient region of the Martian surface on a northern plain called Arabia Terra, supporting the idea that the now cold and dry Red Planet had a warm and wet climate about 4 billion years ago, according to University College London-led research.

Observers in the UK and Western Europe should find an observing location offering an unobscured eastern horizon an hour before sunrise on Sunday, 10 September to see innermost planet Mercury just 0.6 degrees from Regulus, the brightest star in Leo. Conspicuous planet Venus is your convenient celestial guide to finding Regulus, Mercury and Mars.

Around 3.8 billion years ago, an asteroid more than 150 miles across slammed into the Moon and created the Imbrium Basin — the right eye of the fabled Man in the Moon. New research suggests an Imbrium impactor that was two times larger in diameter and 10 times more massive than previous estimates.