Solar System

Eris, the dwarf planet whose 2005 discovery led to Pluto losing its status as a planet, has passed in front of a star, providing astronomers with the clearest view of it since it was identified. It is about the same size as Pluto and is one of the brightest objects in the solar system, according to the new analysis, released Wednesday by the journal Nature. Scientists' picture of Eris had remained fuzzy because its distance from Earth is so vast: It is about three times farther out from the sun than Pluto.

NASA'sfirst hard look at the protoplanet Vesta has given scientists an unprecedented view of its makeup, terrain and history - and revealed that major activity on this ancient rock occurred far more recently than researchers had expected. Images sent back from NASA's trailblazing Dawn spacecraft reveal the full size of a massive crater in the southern hemisphere and indicate that it may have been made just 1 billion years ago, well after Vesta formed more than 4.5 billion years ago, according to one of half a dozen studies published in Friday's edition of the journal Science.

Besides our one beautiful star, the sun, we have eight planets, several dwarf planets, dozens of moons, millions of asteroids, a trillion comets and — most important of all — us! We call it: our solar system. How did our solar system even get here? What were the ingredients that made the sun and all the planets and other objects? How can we find out? What if we could watch a video and see it all unfold again? When the video starts, we see a huge, wispy cloud of gas and dust swirling slowly throughout a huge region of space.

The chest-high rack of electronics Justin Kasper is assembling in a Massachusetts office park will fit in a shoe box before he's done. It won't be much to look at - a few inches across, shaped rather like a coffee cup attached to a Kindle - but to Kasper, it'll serve as eyes across nearly 100 million miles of space. In less than seven years, that cup will be journeying to the center of the solar system to scoop up bits of the sun. "This really has been a life's dream," said Kasper, of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass.

Scientists have confirmed the existence of two Earth-sized, rocky planets orbiting a star called Kepler-20, 1,000 light-years away in the constellation Lyra. The planets are the smallest ever confirmed orbiting a sun-like star, and their discovery, reported Tuesday, is an important milestone for NASA's Kepler mission, which faces the technically daunting task of finding small, Earth-like worlds in faraway solar systems that may — or may not — have been able to sustain life in the past.

Want to explore the solar system and follow NASA space missions in real time? NASA is giving the public the chance to do just that through a new Internet-based tool called Eyes on the Solar System. The space agency said the tool combines video game technology and NASA data to create an environment for users to ride along with agency spacecraft as they explore the cosmos. "You are now free to move about the solar system," Blaine Baggett, a manager at NASA's Jet Propulsion Laboratory in La Cañada Flintridge, said in a statement.

Physicist Brian Cox is the nerd who is cooler than you. In the parallel universe known as Britain, which occasionally intersects with ours, he is a media star, the figure of choice for explaining science to the people — a Carl Sagan with a Britpop haircut, a Lancashire accent and a permanent toothy smile. He's less well known here, though you may have seen the online TED video in which he describes his work at the Large Hadron Collider in Switzerland. (His "main research interest" there, he writes on his website, "is the FP420 R&D project, aimed at upgrading ATLAS and CMS with forward proton detectors 420m away from the interaction points."

A tiny satellite circling Earth is providing an unexpectedly complicated picture of the solar system's heliosphere, the invisible bubble that extends far beyond the planetary orbits to where the solar wind strikes the vast sea of particles and radiation that fill interstellar space, researchers said Thursday. It turns out the heliosphere is changing much more rapidly than scientists ever expected, according to data published Thursday in the Journal of Geophysical Research. Despite its great distance from Earth, the heliosphere is of great interest to astronomers because it shields the solar system from as much as 90% of the cosmic rays that would otherwise enter it. As humans contemplate manned spaceflights of longer durations, "galactic cosmic radiation turns out to be the most important factor" for the safety of astronauts, astronomer David McComas of the Southwest Research Institute in San Antonio said at a news conference.

Question: What is a planet? Answer: Something round that orbits a star, according to the new definition proposed last week by the International Astronomical Union. In the case of our solar system, that star is the sun. Q: Didn't we already know that? A: Actually, no. Although many people thought they knew what a planet was, there had been no clear definition that all astronomers could agree on. Q: So why do we need one now? A: Recent discoveries of bodies in the Kuiper Belt, a huge region of icy objects beyond the orbit of Neptune, raised the question of whether they should be considered planets.

The Sunborn A Novel Gregory Benford Warner Books: 330 pp., $24.95 * Gregory Benford's new novel, "The Sunborn," is a sequel to "The Martian Race," in which a private consortium led by biochemical magnate John Axelrod won a $30-billion prize by outstripping sluggish, bureaucratic NASA in a contest to colonize the Red Planet. Two decades have passed. Axelrod's astronauts, Julia and Viktor Barth, have become the First Couple in a thriving settlement on Mars.

When President John F. Kennedy announced in 1961 that America was committed to "landing a man on the moon and returning him safely to the Earth" by the end of the decade, winning the race became the paramount objective of the national space program. But UC San Diego nuclear chemist James R. Arnold played a crucial role in drawing official attention to another goal: preserving and studying the soil and rock samples that Apollo astronauts would bring back with them. Arnold, 88, who died Jan. 6 in La Jolla from complications of Alzheimer's disease, was a member of a group of four scientists — dubbed the Four Horsemen by colleagues — who sounded the alarms that led NASA to establish a program for analyzing what proved to be a treasure trove for lunar research.

At the Jet Propulsion Laboratory in La Cañada Flintridge, the New Year's celebration will have to wait - until 2:05 p.m. Sunday, to be exact. That's when the second of two NASA spacecraft is expected to enter the moon's orbit on a $496-million mission scientists hope will provide unprecedented insight into the interior composition of Earth's closest neighbor. On Saturday afternoon, the first satellite constituting the Gravity Recovery and Interior Laboratory successfully entered the moon's orbit after a 3 1/2-month trip from Earth.

Scientists have confirmed the existence of two Earth-sized, rocky planets orbiting a star called Kepler-20, 1,000 light-years away in the constellation Lyra. The planets are the smallest ever confirmed orbiting a sun-like star, and their discovery, reported Tuesday, is an important milestone for NASA's Kepler mission, which faces the technically daunting task of finding small, Earth-like worlds in faraway solar systems that may — or may not — have been able to sustain life in the past.

Get psyched, people of Earth: There's an asteroid headed our way. On Tuesday, the asteroid known as YU55 will come closer to our planet than any other asteroid has come since 1976. Of course, when it comes to outer space, "close" is a relative word. Scientists at the Jet Propulsion Laboratory in Pasadena say YU55 will come within 201,700 miles of Earth and no closer. That's nearer than we are to the moon, but far enough away to eliminate the possibility of a collision. "We know exactly where it is going to be, and we don't have any chance of impact for the following hundred years," Marina Brozovic, a scientist and member of the JPL Goldstone radar team, told The Times.

Eris, the dwarf planet whose 2005 discovery led to Pluto losing its status as a planet, has passed in front of a star, providing astronomers with the clearest view of it since it was identified. It is about the same size as Pluto and is one of the brightest objects in the solar system, according to the new analysis, released Wednesday by the journal Nature. Scientists' picture of Eris had remained fuzzy because its distance from Earth is so vast: It is about three times farther out from the sun than Pluto.

SolarCity, one of the country's largest residential solar energy system providers, plans to double the amount of rooftop installations across the country by setting up sun-powered systems on 160,000 homes and other buildings on military bases. The five-year, $1-billion SolarStrong project targets rooftop solar installations at 124 military housing developments in 33 states. SolarCity has already lined up a conditional commitment for a $344-million loan guarantee from the federal government.

Tiny meteorites found in ultra-pure Antarctic snow may provide scientists with evidence that the building blocks of life may have come from within our own solar system, rather than from the far reaches of space, researchers reported in a paper published online Thursday in the journal Science. Scientists have for years been trying to mark a clear line between which materials, including carbon-rich organic materials, formed within our solar system and which came from outer space. "This line is very, very difficult to draw," said study lead author Jean Duprat, a physicist at the University of Paris-South in France.

The twin Voyager space probes have found the first evidence of the existence of the true edge of the solar system, where solar wind hits interstellar space, NASA announced Wednesday. Although many people wrongly believe that the solar system ends with the outermost planet, scientists say its true edge is farther away from the sun at the "heliopause," where electrically charged particles spewed by the sun collide with similar particles in interstellar space.

Want to explore the solar system and follow NASA space missions in real time? NASA is giving the public the chance to do just that through a new Internet-based tool called Eyes on the Solar System. The space agency said the tool combines video game technology and NASA data to create an environment for users to ride along with agency spacecraft as they explore the cosmos. "You are now free to move about the solar system," Blaine Baggett, a manager at NASA's Jet Propulsion Laboratory in La Cañada Flintridge, said in a statement.

The first dust samples ever retrieved from an asteroid and brought back for study show that a portion of the most common meteorites to hit Earth may have come from a single rocky ancestor in space, Japanese researchers say. In a wide-ranging analysis of tiny fragments collected from the asteroid Itokawa during a spacecraft visit in 2005, six studies by several teams of scientists released Thursday by the journal Science piece together a detailed...