Near Earth Object Maps

Below are maps of the inner Solar System for the years 1800, 1850, 1900, 1950, 1990, 2000 and 2007 showing the rate of discovery of the asteroids. Click on the images for the full size versions.

1800
no known asteroids
1850
10 asteroids known and named
1900
hundreds of known objects in the main belt,
some even inside the orbit of Mars
1950
almost 2000 known objects
with a handfull of Earth crossers
1990
over 9,000 known objects
2000
automated searches bring the total to 86,374
2007 August
379,084 known objects ranging from a few metres up to the dwarf planet Ceres

Legend:
Green dots represent objects which do not approach the Earth at present e.g. Main Belt asteroids
Yellow dots represent objects which approach the Earth but do not cross its orbit e.g. Amor asteroids
Red dots represent objects which cross the Earth's orbit e.g. Aten and Apollo asteroids

See also:

Animation of the discovery of the asteroids

Animation of the Inner Solar System

Map of the Inner Solar System for today

Map of objects currently within 45 million kilometres of the Earth

NEO Impact Hazard Information

Asteroid and comet animations

Presentation to Parliamentary Astronomy and Space Environment Group

Near Earth Objects Dynamic Site

Near-Earth Object Program Office at NASA

The NEO Page

Last Revised: 2010 March 4th