Large asteroid set to shoot by Earth on Halloween

Despite spooky nickname, asteroid is “not going to pose any hazard to the Earth” during flyby.

(OCTOBER 29, 2015) (NASA/JPL-CALTECH) – A large asteroid that scientists only discovered this month will make a relatively close approach to Earth on Saturday (October 31), astronomers say, providing one of the best opportunities in years to gather data about a passing space rock.

“Well until recently, we didn’t know very much about this asteroid. It was basically just a point of light. We knew a little bit about what asteroid type it was but in the next day or two we’re going to know a lot about it. Since it’s so bright, the optical telescopes can get an idea of its composition, we’ll take spectra of it, we’ll learn what minerals it has and then the radar will be really spectacular because it’s coming so close. We’ll get a great radar image, we’ll know what its shape is, how fast its rotating and in what orientation its rotating, what the surface looks like. We’re going to learn a lot about this asteroid,” said Paul Chodas, manager for the Center of Near Earth Studies at NASA’s Jet Propulsion Laboratory.

The asteroid, estimated to be about 1,300 feet (400 meters) in diameter, will shoot past the planet at 22 miles (35 km) per second at around 1 p.m. (1700 GMT) on Halloween afternoon. Known as 2015 TB145, it will come within about 300,000 miles (480,000 km) of Earth, farther away than the moon but relatively close by cosmic measures.

Astronomers hope to capture radar images and other measurements of the asteroid during the encounter, a rarity for scientists who typically rely on expensive robotic space probes to gather information about such rocky bodies. Scientists expect to learn about the asteroid’s shape, dimensions, surface features and other characteristics.

Aside from pure scientific value, the encounter may help engineers develop better tracking techniques and countermeasures for asteroids that may be on a collision course with Earth.

“If we ever had to deflect an asteroid we would need to know a lot about it. And we don’t know much about asteroids in general, their structure, how strong they are, are they fill of holes, is it like swiss cheese or are they more solid. We really don’t know the average density of a lot of the asteroid types so we need to learn more about how asteroids are put together, their structure, if we ever want to deflect one that’s headed toward the earth,” said Chodas.

Small space rocks rain down on Earth constantly, with most disintegrating as they blaze through the atmosphere.

About 65 million years ago, an asteroid or comet roughly six miles (10 km) in diameter crashed into what is now Mexico’s Yucatan peninsula, triggering global climate changes that killed off the dinosaurs along with about 75 percent of life that existed at the time, scientists say.

More recently, a 65-foot-wide (20 m) asteroid broke apart over Chelyabinsk, Russia, in February 2013, shattering windows and damaging buildings. More than 1,000 people were injured by flying debris.

Asteroid 2015 TB145 is expected to flyby without causing any danger to earth or humans.

“Well, let’s be clear, this asteroid will pass safely by the earth. It’s not going to hit us and we will know its orbit really well so we can project it into the future and see whether or not it comes near the earth again and we’ve done that and it’s not going to pose any hazard to the earth in certainly the next century,” said Chodas.

NASA is working to map potentially dangerous asteroids and comets that pass within 30 million miles (48 million km) of Earth.

Asteroid 2015 TB145 was discovered less than three weeks ago.