The European Space Agency and the European Southern Observatory launched a program to track potentially threatening near-Earth objects, NEOs. As part of the Space Situational Awareness program, asteroid 2009 FD was observed and found to be less likely to hit Earth than previously believed.

Asteroid 2009 FD New observations from ESO and ESA have reduced the potential threat of asteroid 2009 FD. Photo: ESO

According to ESA, asteroid 2009 FD was in the top five of potential threats to Earth. The NEO Coordination Center has an updated list of 10,524 known NEOs, with 430 considered to be risks. The agencies use the Palermo Technical Impact Hazard Scale to measure potential risk.

Prior to the new observation by ESO/ESA, using the Very Large Telescope, VLT, asteroid 2009 FD had a rating of -1.8 on the Palermo scale. Now it has dropped significantly, with the new observations placing the threat of asteroid 2009 FD at -2.6.

The Palermo scale calculates the level risk of a NEO with a background event, described as the “status quo,” averaging the threat of similar-sized objects throughout history. The risk level is exponential: Any threat below -2 likely poses no threat, but any NEO with a level between -2 and 0 should be observed carefully, with 0 indicating a threat equal to the background hazard. A +1 rating indicates the threat is 100 times more likely to hit Earth than a background hazard.

The Palermo Scale and Torino Scale are both used to determine the potential risk of NEOs, but the former is used in the scientific community and the latter is used to communicate the threat level to the public.

With its new rating, the team believes there is a low-risk possibility of impact but expects those odds to be reduced further following more observations. “These computations showed that there are still some low-probability impact solutions, ranging from the years 2185 to 2198. Yet they are likely to disappear within the next few months, when 2009 FD will become progressively brighter,” reports the NEO Coordination Center.

As of 2013, asteroid 1950 DA has the highest rating on the Palermo Scale. The NEO is listed at -0.83 and has a small chance of hitting Earth in 2880.