Atom & Cosmos

Stormy weather for Saturn
Giant planets have giant storms, and Saturn is no exception. In December, a massive thunderstorm smeared itself across the ringed world, creating a Great White Spot 17,000 kilometers across and bursting with lightning as often as 10 times each second. Intensely stormy weather occurs roughly once each Saturnian year, the equivalent of 29.5 Earth-years. Two teams of scientists describe the latest storm July 7 in Nature. One team reports that Saturn’s lightning releases radio waves 10,000 times stronger than those on Earth; the other team suggests the storm is fueled by a reservoir of water vapor and originates deep in the planet’s cloudy cover. —Nadia Drake

Hybrid exoplanets
When it comes to plate tectonics, some exoplanets may be half Earth, half Venus. Astronomers at the University of Hawaii at Manoa used numerical simulations to explore conditions on Earth-mass planets that always show the same face to their stars’ searing rays. When the temperature difference between the day and night sides of such a planet is at least 400 kelvins (Mercury’s daily change is around 600 kelvins), the asymmetrical movement of molten material beneath the surface may cause plates of crust on the night side to move but leave a single lidlike plate on the day side, the astronomers report online June 23 on arXiv.org. When present, an atmosphere tends to redistribute heat and make the whole surface a volcanic lid, like on Venus. —Camille Carlisle

Dark matter emissions
Astrophysicists suggest that mysterious radio signals from the Milky Way’s center may come from the death of particles of dark matter, the unseen stuff making up most of the universe’s mass. The signals come from inside long, thin structures that extend dozens of light-years and have enigmatic origins and energies. FermiLab and Northwestern University scientists now suggest online June 28 on arXiv.org that the annihilation of a kind of dark matter particle called a WIMP would produce the signals observed. The range of particle masses implied by the observations matches the masses predicted from previous space and ground experiments. —Camille Carlisle

Visiting Vesta
After a 1.7-billion-mile journey, NASA’s Dawn spacecraft is set to arrive at the asteroid Vesta at 1 a.m. EDT on July 16. Launched in 2007, Dawn will spend one year orbiting the second-largest body in the asteroid belt, a chunk of rock that is 330 miles across and is the probable source of many meteorites that sprinkle Earth. Vesta is believed to have formed in the very young solar system, so scientists hope that studying it will reveal information about conditions in those early years. Before leaving Vesta, Dawn will buzz just 120 miles above the asteroid’s cratered surface. Then, the spacecraft will zip over to the dwarf planet Ceres. —Nadia Drake

Betelgeuse is leaking stardust
Red supergiant star Betelgeuse is blowing an enormous cloud of stardust into space. The newly imaged cloud, or nebula, stretches nearly 60 billion kilometers from the star’s surface — and the star is sporting a big, bubbling blister. Astronomers used Europe’s Very Large Telescope to image the supergiant and reported the results online June 23 in Astronomy & Astrophysics. Betelgeuse is the second-brightest star in the constellation Orion and has a radius equal to the distance between Jupiter and the Sun. Its massive cloud of star dandruff contains elements that form the crusts of planets like Earth — elements that are produced in enormous stars before the stars go supernova. —Nadia Drake