Scientists have discovered a 600-mile-long valley on Mercury that may be the first evidence of buckling of the planet’s outer silicate shell in response to global contraction. The researchers discovered the valley using a new high-resolution topographic map of part of Mercury’s southern hemisphere created by stereo images from NASA’s MESSENGER spacecraft.
Images from NASA’s MESSENGER spacecraft reveal previously undetected cliff-like landforms on Mercury that scientists believe must be geologically young, which means that the innermost planet is still contracting and that Earth is not the only tectonically active planet in our solar system, as previously thought.
On Monday, 9 May there will be a rare transit of Mercury, when the innermost planet in our solar system will pass directly between the Earth and the Sun. The last time this happened was in 2006. With a properly filtered telescope and fine weather, the entire 7½-hour event can be seen from the British Isles.
Sprawling across Pluto’s icy landscape is an unusual geological feature that resembles a giant spider. This enhanced colour image, obtained by NASA’s New Horizons spacecraft on 14 July 2015, consists of at least six extensional fractures (arrowed) converging to a point near the centre. Curiously, the spider’s “legs” expose red deposits below Pluto’s surface.