Astronomers Find New Class Of Asteroid

July 01, 1998

University of Hawaii astronomers have discovered a new type of asteroid, whose orbits lie completely within the orbit of the Earth.

Previously, all known asteroids traveled in an orbit farther from the Sun than the Earth, over at least a portion of their journey.

"All other efforts to discover asteroids on a collision course with the Earth are being directed at a region of the sky almost opposite the Sun," said David Tholen, planetary astronomer at the Institute for Astronomy.

"The significance of this discovery is that we would have otherwise never found this new asteroid because it apparently doesn't travel to that region of the sky being scanned by other search efforts."

If such an asteroid's orbit around the Sun intersects with the Earth's orbit, it could hit the Earth and we would have never seen it coming, said Tholen. We would have been caught unaware by an asteroid approaching us from the daytime side of the sky, he said.

Tholen and graduate student Robert Whiteley made the observation using a specialized camera fitted on the University of Hawaii's 2.24-meter telescope atop Mauna Kea last February.

While scanning the dusk and dawn skies to assess the size and number of asteroids within the Earth's orbit, Whiteley spotted the object, since designated 1998 DK36, on his computer screen, shortly after Tholen had recorded the images at Mauna Kea Observatory and sent them to Whiteley's computer via the Internet.

Additional observations made the following night made it possible to compute a preliminary orbit of the object around the Sun. Tholen said the exact size and shape of the asteroid orbit remain uncertain. However, the orbit's farthest point from the Sun could be determined relatively accurately, and it appears to be very close to, but slightly inside the orbit of the Earth.

The asteroid is thought to be about 40 meters in diameter, similar in size to the one that flattened the Tunguska region of Siberia on June 30, 1908, as well as the iron object that produced Meteor Crater in Arizona 50,000 years ago.

Could it collide with the Earth?

"We were unable to obtain enough observations to perform a formal probability calculation, though the best-fitting orbit has the object passing an apparently safe 750,000 miles from the Earth's orbit," said Tholen. "To do a better job with such discoveries, we really need to have a telescope that we can dedicate to such difficult observations."

"1998 DK36 is nothing to lose sleep over," said Tholen. "It's the ones we haven't found yet that are of concern."

University of Hawaii at Manoa

Related Asteroid Articles from Brightsurf:

Asteroid's scars tell stories of its past
Asteroid Bennu, which was just sampled by NASA's OSIRIS-REx mission, only recently migrated into Earth's neighborhood, according to a detailed analysis of impact marks on boulders on its surface.

Asteroid Ryugu shaken by Hayabusa2's impactor
Professor ARAKAWA Masahiko (Graduate School of Science, Kobe University, Japan) and Hayabusa2 mission members discovered more than 200 boulders, which either newly appeared or moved as a result of the artificial impact crater created by the Japanese spacecraft's Small Carry-on Impactor.

Scientists peer inside an asteroid
New findings from NASA's OSIRIS-REx mission suggest that the interior of the asteroid Bennu could be weaker and less dense than its outer layers--like a crème-filled chocolate egg flying though space.

Designing better asteroid explorers
Recent NASA missions to asteroids have used robotic explorers to gather data about the early evolution of our Solar System, planet formation, and how life may have originated on Earth.

ATLAS telescope discovers first-of-its-kind asteroid
University of Hawai'i telescope discovers extraordinary asteroid with comet-like features that has researchers puzzled.

An iron-clad asteroid
Mineralogists from Jena and Japan discover a previously unknown phenomenon in soil samples from the asteroid 'Itokawa': the surface of the celestial body is covered with tiny hair-shaped iron crystals.

Asteroid impact enriches certain elements in seawater
University of Tsukuba researchers found two processes immediately after the end-Cretaceous asteroid impact that likely supplied chalcophile elements to the ocean, i.e., impact heating and acid rain.

Turbulent times revealed on Asteroid 4 Vesta
Planetary scientists at Curtin University have shed some light on the tumultuous early days of the largely preserved protoplanet Asteroid 4 Vesta, the second largest asteroid in our solar system.

In death of dinosaurs, it was all about the asteroid -- not volcanoes
Volcanic activity did not play a direct role in the mass extinction event that killed the dinosaurs, according to an international, Yale-led team of researchers.

Active asteroid unveils fireball identity
At around 1 a.m. local standard time on April 29, 2017, a fireball flew over Kyoto, Japan.

Read More: Asteroid News and Asteroid Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to