Ganymede, Jupiter's largest moon, is thought to have once had more water than all the water on Earth's surface.

But why? 

Ganymede is the largest moon in our solar system and the only moon with its own magnetic field. The magnetic field causes aurorae, which are ribbons of glowing, hot electrified gas, in regions circling the north and south poles of the moon. Because Ganymede is close to Jupiter, it is also embedded in Jupiter's magnetic field. When Jupiter's magnetic field changes, the aurorae on Ganymede also change, "rocking" back and forth so by watching the rocking motion of the two aurorae, scientists were able to determine that a large amount of saltwater exists beneath Ganymede's crust affecting its magnetic field.
Researchers have detected about 20 rotating dust and gas discs in two clusters hosting exceptionally large and hot stars. The science mystery is how the rotating discs are able to withstand evaporation under such extreme conditions - if there is a Hell, this must certainly be it.

The center of the Milky Way is a nursery for young stars: In its heart, more young stars are born in dark clouds than in any other place in the Galaxy. These stars form in rich groups such as the 'Quintuplet' and 'Arches' clusters. Both star clusters are only a few million years old and contain stars as massive as 100 times the mass of the Sun. 

Most of the times we have looked at Uranus, it has seemed to be a relatively calm place. Well, yes its atmosphere is the coldest place in the solar system.

But, when we picture the seventh planet in our solar system invariably the image of a calming blue hazy disc that the spacecraft Voyager 2 took in 1986 comes to mind.

However, all we have previously known about the atmosphere of Uranus has been ’thrown to the wind’ with observations made last year.

Four billion years ago, a young Mars had enough water to bury its whole surface under 400 feet of ocean, but it is more likely that, as on Earth, it pooled. In the case of Mars, it probably formed an ocean occupying almost half of Mars’s northern hemisphere, reaching a mile deep in some places.

This new finding is based on detailed observations of two slightly different forms of water in Mars’s atmosphere. One is the familiar form of water, made with two hydrogen atoms and one oxygen, H2O. The other is HDO, or semi-heavy water, a naturally occurring variation in which one hydrogen atom is replaced by a heavier form, called deuterium. 
Undefined matter under the envelope of "dark matter" makes up over 80% of the universe - but it has never been directly detected.

But the search is on to narrow it down and a new paper has computationally set limits to the properties of one of the particles which might be identified as dark matter: axions. Due to the high temperature inside stars, photons can turn into axions that escape to the exterior, carrying energy with them.

The simulation indicates that the emission of axions can significantly diminish the time for the central combustion of helium, the so called HB (Horizontal Branch) phase: the energy taken by axions is compensated with the energy provided by nuclear combustion, which leads to a much faster consumption of helium. 
A new type of methane-based, oxygen-free life form can metabolize and reproduce similar to life on Earth.

This hypothetical cell membrane, modeled by a team of researchers, is composed of small organic nitrogen compounds and capable of functioning in liquid methane temperatures of 292 degrees below zero - necessary for a harsh, cold world - specifically Titan, the giant moon of Saturn, a planetary body awash with seas not of water, but of liquid methane, Titan could harbor methane-based, oxygen-free cells.

3753 Cruithne's wacky orbit around the Sun. Image: YouTube, CC BY-SA

We all know and love the moon. We’re so assured that we only have one that we don’t even give it a specific name.

It is the brightest object in the night sky, and amateur astronomers take great delight in mapping its craters and seas.

To-date, it is the only other heavenly body with human footprints.

Ceres is the largest object in the asteroid belt, and NASA’s Dawn spacecraft will arrive at this dwarf planet on March 6, 2015. Pluto is the largest object in the Kuiper belt, and NASA’s New Horizons spacecraft will arrive at this dwarf planet on July 15, 2015.
What is hiding in the large disk of gas and dust encircling the 20 million-year-old star Beta Pictoris?  In 1984 Beta Pictoris was the very first star discovered to be surrounded by a bright disk of dust and debris. Since then, Beta Pictoris has been an object of intense scrutiny with Hubble and ground-based telescopes.