By studying the motions of different stellar populations in the disk of the Andromeda galaxy, researchers have deduced that Andromeda has had a more violent past than our Milky Way. 

The structure and internal motions of the stellar disk of a spiral galaxy hold important keys to understanding the galaxy's formation history. The Andromeda galaxy, called M31 by almost no one except the 2 percent of astronomers who like to insist on renaming and reclassifying things, is the closest spiral galaxy to the Milky Way and the largest in what is called the Local Group of galaxies in our cosmic address. 
In an interstellar race against time, astronomers measured the space-time warp in the gravity of a binary star and determined the mass of a neutron star just before it vanished from view.

The researchers measured the masses of both stars in binary pulsar system J1906. The pulsar spins and emits a lighthouse-like beam of radio waves every 144 milliseconds. It orbits its companion star in a little under four hours.  The mass of only a handful of double neutron stars have ever been measured, with J1906 being the youngest. It is located about 25,000 light years from Earth. 

In a new ESO image of LDN 483 and its surroundings, located about 700 light-years away in the constellation of Serpens (The Serpent), some of the stars are missing.

But it's not a portent of doom, it's space pollution - gas and dust are obscuring Lynds Dark Nebula 483. LDN 483 and its dark cloud are intriguing because such clouds are the birthplaces of future stars. 

How might you make a new Earth? Our Terran "test kitchen" has given us a detailed recipe, it just wasn't clear how transposable it was in other areas, the same way a recipe in Los Angeles might not work as well in Denver. Now, astronomers have found evidence that the recipe for Earth also applies to terrestrial exoplanets orbiting distant stars.

"Our solar system is not as unique as we might have thought," says lead author Courtney Dressing of the Harvard-Smithsonian Center for Astrophysics (CfA). "It looks like rocky exoplanets use the same basic ingredients."

Artist’s impression shows a sunset seen from the super-Earth Gliese 667 Cc. The brightest star in the sky is the red dwarf Gliese 667 C, which is part of a triple star system.

On Dec. 10th, ESA announced the latest important discovery regarding comet 67P/Churyumov–Gerasimenko. Rosetta spacecraft orbiting the comet has found the water vapor from its target to be significantly different to that found on Earth.
Our Milky Way is part of a cluster of more than 50 galaxies that make up the ‘Local Group’, a collection that includes the famous Andromeda galaxy and many other far smaller objects.

And now one more, a tiny and isolated dwarf galaxy almost 7 million light years away, named KKs3. KKs3 was found using the Hubble Space Telescope Advanced Camera for Surveys (ACS) in August 2014 in the southern sky in the direction of the constellation of Hydrus and its stars have only one ten-thousandth of the mass of the Milky Way.

Mars is a very harsh and hostile environment for future human explorers and like any other known planet it has no breathable air.