An asteroid strikes Earth in this artist’s depiction. Credit: Don Davis/NASA

Asteroids – were they a boon or bane when they struck Earth billions of years ago? One would think the period of bombardment was not a good thing for a planet! But a new study shows that the bombardment may actually have created environments where microbial organisms could have survived if they were already there. The study also suggests that such environments may have existed on other planets, such as Mars.

• NASA reports the study.
• University of Colorado news release on the study.
• NASA's astrobiology page.

Astronaut Scott Parazynski on Mount Everest.

A former NASA astronaut is searching for signs of hardy life on Mount Everest, which could provide a window into extreme environments that organisms might inhabit on hostile-appearing planets elsewhere in universe. Scott Parazynski’s mission makes him the first astronaut to scale Mount Everests.

• AOL on the astronaut's trip.
• Discovery Channel Q&A with astronaut Scott Parazynski.
• Space.com on the climb.

Astronomers capture an image of a star eight years before its explosive death, casting light on the development of supernovae. A jet of radiation and plasma caused by a black hole is starting to flicker. And recently developed techniques are being used on the Hubble archive to glean new information from old images.

• Hubble Uncovers an Unusual Stellar Progenitor to a Supernova
• Hubble Witnesses Spectacular Flaring in Gas Jet from M87's Black Hole
• Hubble Finds Hidden Exoplanet in Archival Data

Hubble after being released by the shuttle's robotic arm.

The Hubble Space Telescope has been restored after the hugely successful servicing mission by the Space Shuttle Atlantis astronauts and the hundreds of personnel who work on Hubble at NASA and elsewhere. Two new instruments are onboard, two instruments were repaired, and the telescope received new batteries, gyroscopes, and a computer for handling the science data.

• HubbleSite's Servicing Mission 4 page.
• NASA's Space Shuttle page.

A graph shows the mass of galaxies versus the mass of their central black holes.

Astronomers may have solved the cosmic chicken-and-egg problem of which formed first in the early universe — galaxies or the supermassive black holes seen at their cores. Astronomers believe almost all galaxies have massive black holes at their centers, as well as smaller black holes sprinkled throughout. Evidence is piling up that black holes came first.

• National Radio Astronomy Observatory news release on the finding.
• Curious About Astronomy describes black holes.
• An Introduction to Black Holes.

An artist's depiction of one of the STEREO probes.

The solar system might once have had another planet named Theia. Some researchers believe it existed 4.5 billion years ago and possibly collided with Earth to form our Moon. NASA’s Solar Terrestrial Relations Observatory (STEREO) spacecraft are on their way to look for the debris that would be left over after such a collision.

• Science@NASA explains the STEREO hunt.
• The Daily Galaxy describes the Theia hypothesis.
• The Register reports on the Theia search.

Artist's depiction of the Gliese 581 planetary system

Astronomers have searched diligently for a planet of the size of Earth. Researchers would love to find such a planet in the zone appropriate for liquid water – what they call “the habitable zone.” New observations from the European Southern Observatory indicate that the star Gliese 581 has a fourth planet in addition to the known 3. The other planets are large “super earths” and one Neptune-sized planet. But the new planet is about twice the mass of Earth, and could be close to the habitable zone as well.

• ESO news release on the discovery.

Hubble anniversary image of galaxy clusters 1E 0657-556.

Hubble is celebrating its 19th anniversary by releasing new, beautiful images. One image shows a complex interaction of four galaxies in a group called Arp 194. This group’s numerous star clusters formed recently as a result of the galaxies’ gravitational interaction. A second image of two clusters of colliding galaxies, called 1E 0657-556, was also released for the birthday. The galaxies passed through one another, leaving large amounts of gas behind, in the center of the collision.

• Hubble's 19th Anniversary images.