2011 MD is an Apollo asteroid that passed relatively close to Earth's surface — at a distance of about 12000 kilometres (7,456.5 mi), roughly the diameter of the Earth — at around 17:00 UTC (13:00 EDT) on June 27, 2011. Although the object was initially believed to be space junk

Space debris

Space debris, also known as orbital debris, space junk, and space waste, is the collection of objects in orbit around Earth that were created by humans but no longer serve any useful purpose. These objects consist of everything from spent rocket stages and defunct satellites to erosion, explosion...

, subsequent observations confirmed that it is an asteroid

Asteroid

Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...

.

A few hours before the asteroid's nearest approach in 2011, it appeared close to the Sun, so observations were possible for only a brief period. Backyard astronomers were able to observe it with telescopes from Australia, southern Africa, and the Americas.

The asteroid was discovered on June 22, 2011, by the Lincoln Near-Earth Asteroid Research

Lincoln Near-Earth Asteroid Research

The Lincoln Near-Earth Asteroid Research project is a cooperative project between the United States Air Force, NASA, and MIT's Lincoln Laboratory for the systematic discovery and tracking of near-Earth asteroids. LINEAR was responsible for the majority of asteroid detections since 1998 until...

 (LINEAR) pair of robotic telescopes in New Mexico

New Mexico

New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...

, and according to rough estimates, the asteroid's length is between 10 and 45 m (32.8 and 147.6 ft).

Emily Baldwin of Astronomy Now

Astronomy Now

Astronomy Now is a monthly British magazine on astronomy and space. It features a mix of articles ranging from how to observe the night sky to the latest discoveries in the Solar System and in deep space. The first issue of Astronomy Now was published in April 1987 by Intra Press, initially as a...

said that there was no threat of collision, and should the asteroid enter Earth's atmosphere

Earth's atmosphere

The atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention , and reducing temperature extremes between day and night...

, it would "mostly burn up in a brilliant fireball, possibly scattering a few meteorite

Meteorite

A meteorite is a natural object originating in outer space that survives impact with the Earth's surface. Meteorites can be big or small. Most meteorites derive from small astronomical objects called meteoroids, but they are also sometimes produced by impacts of asteroids...

s", causing no likely harm to life or property on the ground.

Trajectory plots

Trajectory of 2011 MD projected onto the Earth's orbital plane. Note from this viewing angle, the asteroid passes underneath the Earth.

Trajectory of 2011 MD from the general direction of the Sun.