A research group from the Japan Aerospace Exploration Agency (JAXA) and the Japan Spaceguard Association (JSGA) made observations of the light curve (*1) of near Earth asteroid 2018 EZ2 on the 13th of March 2018 Japan time at the Bisei Spaceguard Center (*2). This asteroid was determined to be spinning at a rate of once every 172 seconds. Additionally, the asteroid's shape was found to be long and thin, with an axial ratio of 1.7 to 1.0.
The JAXA research and development department discovered this asteroid at the Siding Spring Observatory in Australia at 7:05 PM on the 12th of March Japan time. By making their observations as the asteroid grew in brightness directly after discovery, the department succeeded in detecting the asteroid while it spun at such a high speed. According to the Jet Propulsion Laboratory (JPL) in the United States, this asteroid came as close as 210,000 km from the Earth (within the lunar orbit) at 11:41 AM on the 14th of March Japan time.
The diameter of the asteroid was estimated to be 20 meters, roughly the same size as the Chelyabinsk meteorite that struck Russia in 2013, causing significant damage. The asteroid has a strong inner structure that can withstand the centrifugal force created by high speed rotation. The results of these observations will help to clarify the physical conditions of asteroids approaching Earth.
Note 1: A light curve refers to the data for changes in the brightness of an asteroid over time. If you are able to obtain the light curve, you can estimate the shape and rotation period.
Note 2: Bisei Spaceguard Center: An observatory jointly operated by the Japan Aerospace Exploration Agency (JAXA), the Japan Space Forum (JSF), and the Japan Spaceguard Association. The observatory mainly observes space debris and small solar system bodies.