Saturn's rings are made up of particles and chunks of mostly water ice.

A new proposal suggests that Saturn’s rings may have come from a planet-size collision. A moon the size of Mercury may have smashed into Saturn to create its spectacular ring system.

• Discovery News on this topic.
• Universe Today on Saturn's ring formation.
• Nine Planets on Saturn.

A graphic depicts the formation of the universe starting with the Big Bang.

The universe began with a hot explosion called the Big Bang. The aftermath of the Big Bang consisted mostly of radiation, but as things cooled, the elements hydrogen and helium formed. Hubble’s new Cosmic Origins Spectrograph is giving us information about the early formation process, including the development of galaxies and the “re-ionization” of the universe.

• HubbleSite news release on this topic.

Hubble spies an X-shaped object streaking through space — and learns what created it. And the Dawn spacecraft is zeroing in on the asteroid Vesta. Learn how Hubble is helping it get there.

• Hubble Finds that a Bizarre X-Shaped Intruder is Linked to an Unseen Asteroid Collision
• NASA Mission to Asteroid Gets Help from Hubble Space Telescope

Energetic particles produced near M87's black hole lift the coolest gas near the galaxy's center. Credit: X-ray (NASA/CXC/KIPAC/N. Werner, E. Million et al); Radio (NRAO/AUI/NSF/F. Owen)

The giant elliptical galaxy, M87, has a supermassive black hole in its center. A long jet extends outward from the core of the galaxy, and huge radio lobes reach into space. New X-ray and radio data from the Chandra X-Ray Observatory and the Very Large Array Radio Observatory show that eruptions from the core of M87 have long-range effects. The hot eruptions stop cool gas from falling toward M87’s center to form new stars, and even affect surrounding galaxies.

• Chandra Press Release.

The nucleus of Halley's Comet is shown in this image, captured by the European Space Agency's Giotto spacecraft. Credit: ESA

A celestial event recorded by the ancient Greeks may be the earliest sighting of Halley’s Comet, which would push accounts of Halley back 226 years. According to ancient writers, a large meteorite smacked into northern Greece between 466 B.C. and 467 B.C. — but the writers also describe a comet in sky at time that the meteorite fell to Earth.

• The BBC reports on the story.
• A Brief History of Halley's Comet
• About.com on Halley's Comet.

Mars' moon, Phobos, taken by the Mars Reconnaissance Orbiter. Phobos' huge Stickney crater is visible.

The origin of the two moons of Mars — Phobos and Deimos — has been a long-standing puzzle. Now, new evidence indicates that Mars’ largest moon, Phobos, is made from rocks blasted off Martian surface in a catastrophic event. Astronomers have speculated that both moons could be asteroids that were captured by Mars’s gravity, but the latest evidence supports another, more violent possibility.

• Science Daily on the discovery.
• Scientific American on the discovery.

Credit: NASA/GSFC/Arizona State University
A natural bridge on the Moon, imaged by the Lunar Reconnaissance Observer.

The Lunar Reconnaissance Observer has mapped the surface of the Moon. Researchers have examined the imagery and cataloged multitudes of craters on the surface. Interested members of the public, known as citizen scientists, can participate in the cataloging. Participants have found interesting craters, bridge arches, and lava tube “skylights” through the Moon Zoo program.

• How to participate in Moon Zoo.
• The Moon Zoo Blog.
• Wired Magazine on the topography of the Moon.

An artist's concept of a piece of solar system debris that belongs to a class of bodies called trans-Neptunian objects.

The material left in the outer part of the solar system can contain clues to the formation and early stages of the Sun and its planets. A plethora of rocky objects, comets and possibly dwarf planets reside in our solar system well beyond the orbit of Neptune. Most are small, dark objects that are very hard to find because they reflect so little light. Using the Hubble archive, a team searched some of the images and found new distant solar system objects. They range in size and suggest a fair number of collisions have occurred throughout the 4.5 billion year lifetime of the Sun.

• Harvard-Smithsonian Center for Astrophysics news release.
• HubbleSite news release.
• Space.com on the discovery.