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Encyclopedia > Numbers about the solar system XV
Relationship
between absolute magnitude and diameter of the asteroids
The table below provides the relationship between the absolute magnitude (magnitude
of a body located at one astronomical unit from the Earth)
of an asteroid and its size. The uncertainty on this size depends on
the uncertainty on the brightness of the objects and on the
value of the albedo. For a bright asteroid (albedo around 0.25), one will read
the first value for the size and for a dark asteroid (albedo
around 0.05), one will read the second value.
So, for example, an asteroid the absolute magnitude of which
being 7 could hace a diameter of 240 kilometers if it is dark
and only a diameter of 110 kilometers if it is bright.
| Absolute magnitude |
Diameter in kilometers | Absolute magnitude | Diameter in meters | |
|---|---|---|---|---|
| 2.5 | 840 - 1900 | 17.5 | 810 - 1800 | |
| 3.0 | 670 - 1500 | 18.0 | 670 - 1500 | |
| 3.5 | 530 - 1200 | 18.5 | 530 - 1200 | |
| 4.0 | 420 - 940 | 19.0 | 420 - 940 | |
| 4.5 | 330 - 740 | 19.5 | 330 - 740 | |
| 5.0 | 260 - 590 | 20.0 | 260 - 590 | |
| 5.5 | 210 - 470 | 20.5 | 210 - 470 | |
| 6.0 | 170 - 370 | 21.0 | 170 - 370 | |
| 6.5 | 130 - 300 | 21.5 | 130 - 300 | |
| 7.0 | 110 - 240 | 22.0 | 110 - 240 | |
| 7.5 | 85 - 190 | 22.5 | 85 - 190 | |
| 8.0 | 65 - 150 | 23.0 | 65 - 150 | |
| 8.5 | 50 - 120 | 23.5 | 50 - 120 | |
| 9.0 | 40 - 95 | 24.0 | 40 - 95 | |
| 9.5 | 35 - 75 | 24.5 | 35 - 75 | |
| 10.0 | 25 - 60 | 25.0 | 25 - 60 | |
| 10.5 | 20 - 50 | 25.5 | 20 - 50 | |
| 11.0 | 17 - 37 | 26.0 | 17 - 37 | |
| 11.5 | 13 - 30 | 26.5 | 13 - 30 | |
| 12.0 | 11 - 24 | 27.0 | 11 - 24 | |
| 12.5 | 8 - 19 | 27.5 | 8 - 19 | |
| 13.0 | 7 - 15 | 28.0 | 7 - 15 | |
| 13.5 | 5 - 12 | 28.5 | 5 - 12 | |
| 14.0 | 4 - 9 | 29.0 | 4 - 9 | |
| 14.5 | 3 - 7 | 29.5 | 3 - 7 | |
| 15.0 | 3 - 6 | 30.0 | 3 - 6 | |
| 15.5 | 2 - 5 | 30.5 | 2 - 5 | |
| 16.0 | 2 - 4 | 31.0 | 2 - 4 | |
| 16.5 | 1 - 3 | 31.5 | 1 - 3 | |
| 17.0 | 0.9 - 2 | 32.0 | 0.9 - 2 |