Legion of Angels News Archive

A good-sized asteroid sailing past our planet right now turns out to be two giant rocks doing a celestial jig.

The setup, catalogued as 2008 BT18, was thought to be nearly a half-mile wide after its discovery by MIT’s LINEAR search program in January. Nothing else was known about it.

Now seen as two objects orbiting each other, the pair will be closest to Earth on today, at about 1.4 million miles (2 million kilometers) away. That’s nearly six times as far from us as the moon.

It will not strike the planet. But scientists want to learn more about binary asteroids because one day they might find one headed our way. Deflecting a binary off course could be considerably more challenging that altering the path of a single rock.

Radar observations from the Arecibo Observatory in Puerto Rico on July 6 and 7 “clearly show two objects,” said Lance Benner of NASA’s Jet Propulsion Laboratory.

The objects are estimated to be 1,970 feet (600 meters) and 650 feet (200 meters) in diameter. The larger one rotates upon its axis in 3 hours or less.

Additional observations from NASA’s Goldstone radar in the Mojave Desert in California are expected to reveal more about the density, shapes and orbit of the pair.

Asteroids are often loose rubble piles rather than solid objects, and pairs are common. Scientists announced earlier this month that binaries can be created when energy from sunlight splits a loose asteroid in two.

While most asteroids roam in a belt between Mars and Jupiter, some are kicked or drawn inward and cross our path around the sun. Some 15 percent of these near-Earth asteroids are binaries. But few come so close.

Asteroid 2008 BT18 remains classified by NASA as “potentially hazardous” because its future orbits have not been fully determined.

Asteroids are known to change course over time, and in fact one big boulder, named Apophis, will alter course significantly during a close Earth flyby in 2029. Earth’s gravity will bend the rocks’ trajectory around the sun. Depending on how that interaction plays out, Apophis has a minor chance of hitting the planet in 2036. Scientists expect the odds of impact to diminish or evaporate after the first flyby, however.

Source — MSNBC

WASHINGTON (AP) – When viewed from the rest of the galaxy, the edge of our solar system appears slightly dented as if a giant hand is pushing one edge of it inward, far-traveling NASA probes reveal.

Information from Earth’s first space probes to hit the thick edge of the solar system — called the heliosheath where the solar wind slows abruptly — paint a picture that is not the simple circle that astronomers long thought, according to several studies published Thursday in the journal Nature.

Surprised astronomers said they will have to change their models for what the solar system looks like.

In 1977, NASA launched two space probes on missions beyond the solar system. Voyager 1 went north and Voyager 2 went south. What startled astronomers is that when the two of them hit the heliosheath they did so at different distances from the sun.

Voyager 2 hit the southern edge of the solar system nearly 1 billion miles (1.61 billion kilometers) closer to the sun than Voyager 1 did to the north. Voyager 2 hit the edge at 7.8 billion miles (12.55 billion kilometers) from the sun.

“We used to assume that it’s all symmetric and simple,” said Leonard Burlaga, an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “It’s literally like a hand pushing.”

That push is from the magnetic field that lies between star systems in the Milky Way. The magnetic field hits the solar system at a different angle on the south than on the north, probably because of interstellar turbulence from star explosions, said Voyager project scientist Ed Stone.

Both spacecraft still have several more years before they completely exit the solar system and continue deeper into the space between stars, said Stone, former director of NASA’s Jet Propulsion Lab.

Source — CNN