NASA’s Mars Reconnaissance Orbiter captured this intriguing view of “corduroy” sand dunes rippling across the permanent polar cap of Mars. The dunes “march across a fabric of patterned ground,” according to a NASA caption that explains “at this time of the Martian year the dunes are free of the seasonal dry ie that forms a temporary cover every winter.” Launched in 2005, the MRO braked into orbit around the red planet in 2006 to study the history and distribution of water. Its High Resolution Imaging Science Experiment, or HiRISE, which took the image seen here, is one of the most powerful cameras ever launched aboard a planetary spacecraft.
Mercury attains a greatest easterly elongation of 19 degrees from the Sun on 1 April. This solar separation combined with a favourable inclination of the ecliptic to the western horizon an hour after sunset, means that the period 25 March to around 8 April offers the year’s best evening showing of the innermost planet for Northern Hemisphere observers.
The space environment around a planet plays a key role in determining what molecules exist in the atmosphere – and whether the planet is habitable for life. New research shows that Venus has an “electric wind” strong enough to remove the components of water from its upper atmosphere, which may have played a significant role in stripping Earth’s twin planet of its oceans.