Golevka and the first measurement of the Yarkovsky effect
How twelve years of radar tracking caught sunlight nudging a half-kilometre asteroid by 15 km.
Published 2026-10-23
Around 1900, a Polish-Russian civil engineer named Ivan Yarkovsky wrote in a pamphlet that the daily heating of a spinning object in space should give it a tiny push.[3] For a century, nobody could measure it.
How the effect works
An asteroid’s afternoon side is warmest, because the surface takes time to heat up. Heat radiated from that side carries momentum away and pushes the asteroid slightly the other way. The effect matters most for bodies between about 10 cm and 10 km across.[3]
Why Golevka?
Golevka is small, about half a kilometre, and passes close enough to Earth for radar.[1][2] Radar measures distance and speed very precisely. Arecibo observations in 1991, 1995 and 1999 pinned its orbit down with great accuracy.[3][6]
The result
By 2003, Golevka was 15 km from where gravity alone said it should be.[2] The force behind that drift is estimated at about 0.25 newtons, an acceleration of only 10−12 m/s².[3]
A bonus: its density
How strongly the push moves an asteroid depends on its mass. The measurement gave Golevka a density of 2.7 ± 0.5 g/cm³ and a mass of about 2.1 × 1011 kg.[2]
Why it matters
Without measurements, the effect is very hard to predict, because it depends on shape, spin and albedo. It is now part of how we forecast asteroid orbits and has even been suggested as a way to deflect a threatening one.[3]
Numbered citations link to the sources list on the Golevka overview page.