The international webpage Near Earth Asteroids, a Chronology of Milestones, 1800 - 2200, has a new location. The renewed page is now on line at the site of ESA's NEO Coordination Centre.The NEA Chronology testifies of the enormous amount of work done and being done in the field of Near Earth Asteroids, notably in the last three decades. However, present knowledge of the number of NEAs amounts to a only few percent of the real number. In order to assess the real extent of the NEA Earth impact risk for, let's say, the next 200 hundred years, the world's observing capacity should be enlarged by about two orders of magnitude. For this to be realized, surveys of NEAs by infra-red space observatories will be essential and crucial.
The NEA Chronology, focusing on significant past and future events in the field of Near Earth Asteroids, contains the following information, listed in chronological order:
(a) data of known NEAs with past nominal Earth close approach distances d ? 1.0 Lunar Distances (LD);
(b) data of known NEAs with future nominal Earth close approach distances d ? 10.0 LD and minimum close approach distances d ? 1.0 LD;
(c)scientific literature, conferences and other milestones on NEA research.
The NEA Chronology is updated monthly and can be downloaded as pdf file.
As of 1 January 2016, 13517 NEAs are registred by the IAU International Astronomical Union, ranging in size from a few meters up to about 32 km (the largest one is 1036 Ganymed, with absolute magnitude H = 9.45 mag and diameter D = 31.7 km), including 1650 Potential Hazardous Asteroids, ranging in size from 140 meter up to about 5 km (the largest one is 4179 Toutatis, with absolute magnitude H = 15.3 mag and dimensions of 4.6 × 2.4 × 1.9 km).
By 1 February 2016, the NEA Chronology lists 2730 entries of past events since AD 1800, including 283 close approaches of asteroids ranging in size from 1 to 325 m with nominal Earth close approach distances d ? 1.0 LD, 17 of which with d ? 0.1 LD, and four impacts (in 1908, 2008, 2013, and 2014).
By 1 February 2016, the NEA Chronology lists 231 entries of future events up to AD 2200, of which 188 predicted close approaches of asteroids with nominal Earth close approach distances d ? 10.0 LD and minimum close approach distances d ? 1.0 LD (i.e., about one per year), including 26 predicted close approaches of asteroids with nominal Earth close approach distances d ? 1.0 LD, four of which with d ? 0.1 LD.
The renewed web page Near Earth Asteroids (NEAs), A Chronology of Milestones, 1800 - 2200, managed by Dr. Karel A. van der Hucht of SRON Netherlands Institute for Space Research (Utrecht, the Netherlands) and formerly part of the web site of the International Astronomical Union, is now hosted by the European Space Agency's NEO Coordination Centre at http://neo.ssa.esa.int/web/guest/neo-chronology