Category Astronomy/Space

Mercury appears to undergo a recurring meteoroid shower when its orbit crosses the debris trail left by comet Encke. (Artist’s concept.) Credit: NASA/Goddard

Mercury is being pelted regularly by bits of dust from an ancient comet, a new study has concluded. This has a discernible effect in the planet’s tenuous atmosphere and may lead to a new paradigm on how these airless bodies maintain their ethereal envelopes.

On a clear, moonless night we Earthlings witness dust grains as they burn up in the Earth’s atmosphere in the form of meteors or “shooting stars.” At certain times of the year, their numbers increase manyfold, creating a natural fireworks display: a meteor shower. This is caused by the Earth passing through a stream of dust particles left behind by certain comets.

One of the most ...

Locations of more than 1,000 craters mapped on Pluto by NASA’s New Horizons mission indicate a wide range of surface ages, which likely means that Pluto has been geologically active throughout its history. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

NASA’s New Horizons science team is discussing >50 exciting discoveries about Pluto at this week’s 47th Annual Meeting of the American Astronomical Society’s Division for Planetary Sciences in National Harbor, Maryland. “The New Horizons mission has taken what we thought we knew about Pluto and turned it upside down,” said Jim Green, director of planetary science at NASA Headquarters, Washington.

Eg NH geologists combined images of Pluto’s surface to make 3D maps that indicate two of Pluto’s m...

This is the “South Pillar” region of the star-forming region called the Carina Nebula. Like cracking open a watermelon and finding its seeds, the infrared telescope “busted open” this murky cloud to reveal star embryos tucked inside finger-like pillars of thick dust. Credit: NASA

A type of gas found in the voids between galaxies – atomic gas – appears to be part of the star formation process under certain conditions. The findings overturn a long-standing theory about the conditions needed for star formation to take place – a process that happens when dense clouds of dust and gas inside galaxies collapse.

It was previously thought that stars could form only in the presence of a different type of gas – called molecular gas. Atomic gas is composed of individual H atoms...

Coronal loops on the sun that are linked to magnetic fields. Credit: NASA/Solar Dynamics Observatory Read more at: http://phys.org/news/2015-11-physicists-clue-formation-magnetic-fields.html#jCp

Small magnetic perturbations can combine to form large-scale magnetic fields just like those found throughout the universe. Squire and Bhattacharjee at PPPL analyzed the behavior of dynamos, which occur when an electrically charged fluid like plasma swirls in a way that creates and then amplifies a magnetic field. Scientists have known that plasma turbulence can create lots of small magnetic fields, but the mechanism by which those fields could produce a single large field is elusive.

The puzzle consists of the seeming unlikelihood of small disturbances coming together to form something large and o...