Amateur and professional astronomers are invited to provide observations of comets 41P/Tuttle-Giacobini-Kresák, 45P/Honda-Mrkos-Pajdušáková, and 46P/Wirtanen that will pass by Earth at distances ranging from 0.08 to 0.15 astronomical units. Such close approaches of a trio of comets within the next two years are rare and typically occur only once every few decades.
NASA’s New Horizons spacecraft spied extensional faults on Pluto, a sign that the dwarf planet has undergone a global expansion possibly due to the slow freezing of a sub-surface ocean. A new analysis by Brown University scientists bolsters that idea, and suggests that ocean is likely still there today.
The geologic shape of what were once shorelines through Mars’ northern plains 3.4 billion years ago convinces scientists that two large meteorites – hitting the planet millions of years apart – triggered a pair of mega-tsunamis. These gigantic waves, likely 120 metres high, forever scarred the Martian landscape and yielded evidence of cold, salty oceans.
Astronomers were watching when comet P/2016 BA14 flew close by Earth on 22 March at a distance of slightly more than nine times the distance of the Moon. Radar images from the flyby indicate that the body is about a kilometre in diameter, while infrared spectra indicate that the comet’s nucleus is as dark as fresh asphalt.
Somewhat appropriately spooky for Halloween in recent radar images, 600 metre-wide near-Earth object 2015 TB145 dashes by our planet today. Now believed to be a dead comet that has shed its volatiles after numerous passes around the Sun, the object makes its closest approach to Earth at 5pm GMT. UK observers with clear skies may see it with modest telescopes in the early evening.
Gigantic groundwater outbursts created the largest flood channels in the solar system on Mars, 3.2 billion years ago. For many years it was thought that this was caused by the release of water from a global water table, but research just published reveals regional deposits of sediment and ice emplaced 450 million years earlier to be the source.
Since its arrival at dwarf planet Ceres on 6 March this year, NASA’s Dawn spacecraft has been slowly spiralling closer to this enigmatic little world. Mission scientist are nearer finding explanations for the intriguing bright spots in a crater named Occator and why an isolated mountain — as high as any in North America — is sitting in the middle of nowhere.