Apophis Position Uncertainty
Position uncertainty in 2036 before and after the first radar measurements (ABOVE)
Views looking south from above the solar system. The Sun is at the center. The orbits of the inner four planets are marked with black ellipses. 10,000 orbits statistically possible prior to the January 2005 radar track (green) and shortly after (black) were propagated from 2005 to 2036 using the non-linear Standard Dynamic Model.
Apophis could have been ONE of the dots, but it wasn't known which one. The radar data corrected a bias, moving the nominal position (red) closer to the Earth while reducing the uncertainty in Apophis' predicted heliocentric longitude from 260 to 160 degrees. Figure by J. Giorgini (JPL).
Reference solution (S142) orbit uncertainties in 2036 (ABOVE)
The currently remaining possible positions of Apophis in 2036 (3-sigma region in blue) under the Standard Dynamical Model. The 3-sigma uncertainty in heliocentric longitude, with two more radar experiments and additional optical measurements, is now ~72 degrees. Nominal (most likely) Apophis encounter distance is 0.32 AU. However, the Earth still encounters the uncertainty region at -2.4 standard deviations, producing a small possibility of impact. Figure by J. Giorgini (JPL).
Apophis' Encounter with 2004 VD17 in 2034
Apophis encounters (144898) 2004 VD17, another potentially hazardous asteroid, on 2034-Jul-17.9, under the standard dynamical model. The highest probability prediction is a 6.7 lunar distance approach, with the uncertainty regions within 1.6 lunar distances of each other at a point within 0.15-sigma of Apophis' nominal location. Both +/- 3-sigma regions at the time of closest approach are shown, but 2004 VD17's small uncertainty region (+/- 1800 km 3-sigma) is indistinguishable from the red square indicating the Apophis nominal location within its +/- 51 million km (3-sigma) region. Figure by J. Giorgini (JPL).