As a big asteroid flies by at a close but safe distance from Earth on Saturday (Oct. 31), astronomers will likely get a better radar view of the surface than ever before.

Asteroid 2015 TB145—discovered earlier this month, on Oct. 10—will fly by slightly outside the moon's orbit. In celestial terms, this is rather close, especially considering the asteroid's size.

At an estimated 1,300 feet (400 meters) wide, this is the closest known flyby by a large asteroid until 2027. TB145 will fly by at 300,000 miles (480,000 kilometers) from Earth, but poses no threat to our planet.

It provides a special kind of Halloween treat for astronomers: the chance to view the surface in radar down to a resolution of as little as 2 meters (6.6 feet). Previous flybys yielded a resolution of about half that, 4 meters (13.1 feet).

"What's particularly interesting is the number of boulders on the surface," Paul Chodas, the Jet Propulsion Laboratory's manager of the center of near-Earth object studies, told Space.com.

TB145 can provide an example of what sorts of boulders are on an asteroid's surface, Chodas added. "They want to know in general how the asteroids are built, what is their structure, what is their strength, what is the surface distribution of boulders, how many are there, and how well they're held to the surface."

TB145 was detected by the University of Hawaii's Pan-STARRS-1 telescope (the name's short for Panoramic Survey Telescope and Rapid Response System), which participates in NASA's near-Earth object observation program. According to the Minor Planet Center, this will be the closest known flyby of an asteroid of this size until 2027, when asteroid 1999 AN10 (about 2,600 feet, or 800 meters in size) flies by at about the orbit of the moon.

TB145's weird, elliptical path through space brings it close to the Earth's orbit once every three years. But its brush with us is brief, usually a quick dip in and out before flying farther out in the solar system again. Astronomers think that perhaps past gravitational interactions with Jupiter threw it on the bizarre path.

The asteroid, however, has not come this close to Earth in about 40 years, according to the calculations astronomers ran on its orbit. In 1975, there wasn't really a dedicated search for asteroids and the technology was not as advanced to find asteroids of this size, Chodas said.

(With inputs from Scientific American and space.com)