Posts tagged Astronomy.
The moon, Venus, and Jupiter — the three brightest objects in the night sky — will be putting on a dazzling celestial show shortly after sunset both Feb. 25 and 26, coming together in a tight triangle. With any luck, you might also spot tiny Mercury down near the horizon just as the sun goes down.
People all over the world can check out the performance just by stepping outside and looking westward. If snowstorms or general chilliness drive you inside, you can always watch the spectacular event live on the Slooh Space Camera feed, starting both nights at 6:30 p.m. PST.
Glorious Southern Comet
by David Malin
Comet McNaught 2006 P1, Chiro Observatory in Western Australia. Comet McNaught was the brightest comet in four decades.
Recorded using a pinhole camera between the summer and winter solstice in 2011.
Jupiter’s Solid Core May Be Liquifying Itself
Think climate change is bad? Things are rather worse in the outer solar system. Jupiter’s rocky central core may well be dissolving into liquid.
The gas giant, which is twice as massive as all of the other planets orbiting the Sun put together, has a central core comprised of iron, rock and ice. It sits in the center of the planet, submerged in a fluid of hydrogen and helium under intense pressures about 40 million times greater than atmospheric pressure on Earth, and temperatures around 16,000 degrees kelvin — hotter than the surface of the Sun.
As such, we can’t recreate those conditions experimentally on Earth. But that hasn’t stopped planetary scientists Hugh Wilson and Burkhard Militzer of the University of California, Berkeley, giving it a go. They’ve performed quantum mechanical calculations to try and work out how one of the key ingredients of the core — magnesium oxide — responds in such an extreme situation.
They found that under these intense pressures and temperatures, the magnesium oxide has very high solubility, meaning that it’s likely to be dissolving into liquid. The exact rate of the erosion isn’t known, but the pair had earlier predicted that the ice in the core is also dissolving. That means that Jupiter’s core is likely to be smaller now than it was when the planet formed.
The research has been detailed in a paper submitted to Physical Review Letters, in which Wilson and Militzer say that the work has substantial implications for working out how to simulate these types of planets. “For large exoplanets exceeding Jupiter’s mass, higher interior temperatures promote both solubility and redistribution, implying that the cores of sufficiently large super-Jupiters are likely to be completely redistributed,” it reads.
We’ll be able to find out more in 2016, when NASA’s Juno spacecraft arrives at the gas giant and begins to measure its gravitational field.
Image: NASA/ESA/E. Karkoschka (U. Arizona)