Last week scientists found what looks like an ancient streambed on Mars, witnessed the death of a white dwarf star and welcomed an astronaut home. See the top stories of the last week here.<br> FIRST STOP: Mercury's Surface Resembles Rare Meteorites
Mercury has a surface unlike any other in the solar system, resembling a rare type of meteorite, researchers say. [<a href=http://www.space.com/17727-mercury-surface-rare-meteorites.html>Full Story</a>]<br> NEXT: Earth-Sun Distance Measurement Redefined
– The International Astronomical Society changed a long-standing unit of solar system measurement to a single number that no longer depends on the mass of the sun. [<a href=http://www.space.com/17733-earth-sun-distance-astronomical-unit.html>Full Story</a>]<br> NEXT: Giant Gas Cloud Surrounds Our Milky Way Galaxy
A cloud of gas engulfing our Milky Way that weighs as much as all the galaxy’s stars combined could solve a longstanding astronomical mystery. [<a href=http://www.space.com/17734-milky-way-galaxy-giant-gas-halo.html>Full Story</a>]<br> NEXT: Ocean on Jupiter's Moon Europa Likely Deep Underground
Jupiter’s icy moon Europa has long been thought to hide a vast ocean of water beneath its frozen surface. A new study finds that liquid water near the surface are short-lived. [<a href=http://www.space.com/17741-europa-ocean-jupiter-moon-water.html>Full Story</a>]<br> NEXT: Hubble Telescope Reveals Farthest View Into Universe Ever
The Hubble Space Telescope has captured the farthest-ever view of the universe, a photo that reveals thousands of galaxies billions of light-years away. [<a href=http://www.space.com/17755-farthest-universe-view-hubble-space-telescope.html>Full Story</a>]<br> NEXT: Mars Sample-Return Goal Drives NASA's Exploration of Red Planet
The next steps in NASA's Mars exploration strategy should build toward returning Martian rocks and dirt to Earth to search for signs of past life, a new report by the space agency's Red Planet planning group finds. [<a href=http://www.space.com/17757-mars-sample-return-nasa-future-missions.html>Full Story</a>]<br> NEXT: Knowing Neil Armstrong: One Giant Leap for an Apollo Fanatic
The memorials to the late Neil Armstrong this month resonated with space fans and the public around the world. Apollo historian Andrew Chaikin recalls Armstrong's legacy. [<a href=http://www.space.com/17768-neil-armstrong-andrew-chaikin-memory.html>Full Story</a>]<br> NEXT: Jupiter's Big Moon Ganymede Mapped by Amateur Astronomer
An amateur astronomer has mapped the surface of Jupiter’s moon Ganymede in a first for amateur stargazers. [<a href=http://www.space.com/17782-jupiter-moon-ganymede-amateur-astronomy.html>Full Story</a>]<br> NEXT: Brightest Star Explosion in History Reveals Lonely Supernova
The quick, violent death of a white dwarf is now revealing these kinds of stars can give off powerful explosions by themselves, researchers say. [<a href=http://www.space.com/17776-brightest-star-explosion-lonely-supernovas.html>Full Story</a>]<br> NEXT: Astronauts Can Keep (or Sell) Their Space Artifacts, New Law Says
America's early space pioneers and moon voyagers have now been confirmed as the legal owners of the equipment and spacecraft parts they saved as souvenirs from their missions. [<a href=http://www.space.com/17787-nasa-astronauts-space-artifacts-souvenirs-law.html>Full Story</a>]<br> NEXT: Mars Rover Finds Ancient Streambed Where Water Once Flowed
NASA's Mars rover Curiosity has discovered what appears to be an ancient streambed, suggesting that water once flowed in large volumes — perhaps hip-deep in places — across the Martian surface. [<a href=http://www.space.com/17794-mars-rover-curiosity-water-ancient-streambed.html>Full Story</a>]<br> NEXT: Source of Monster Black Hole's Energy Jet Identified
A peek at swirling matter around a black hole is now pinpointing the tiny region where monstrous blasts of energy erupt from, researchers say. [<a href=http://www.space.com/17792-monster-black-hole-energy-jet-source.html>Full Story</a>]<br> NEXT: 'Avengers' in Space: NASA Astronaut Recounts Movie Nights and Life in Orbit
Astronaut Joe Acaba is back on Earth after a months-long visit to the International Space Station, and is adjusting to life back on the ground. [<a href=http://www.space.com/17804-astronaut-joe-acaba-life-space.html>Full Story</a>]<br>
